impact-of-tsunami-risk-mitigation

WESTMINSTER UNIVERSITY MA INTERNATIONAL PLANNING AND SUSTAINABLE DEVELOPMENT

IMPACT OF TSUNAMI RISK MITIGATION IN URBAN AREAS Can this impact contribute to the urban quality of coastal settlement in a recovery context?

Case studies: Two recovery plans for Chilean coastal settlements Post Tsunami 27February 2010.

ROCIO COSTA W13004516 AUGUST 2011 14.779 words

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ABSTRACT When a settlement is hit by an extreme natural event such a tsunami, a reconstruction process starts with the aim of rebuilding a community better than before and providing a safer environment to face future events. On this matter a recovery context presents unique opportunities to enact policies to mitigate future disasters and to integrate a range of mitigation measures into the urban planning process in order to reduce vulnerability of the affected communities, including improved building codes, more effective land use and community planning. All these actions may have significant impact in the physical system of a settlement and this impact may also have high effects in many aspects of urban sustainability, related to urban growth, development, density and character, but if mitigation it´s linked with broader community goals and urban improvements may become an opportunity to achieve more resilient places. On this matter the role of urban planning and design is essential to make these measures work harmoniously in the overall functions of a community, providing an opportunity not just to create safer places but also improving the entire urban quality and development of a settlement.

This research through the study of two Chilean coastal settlements hit by an earthquake and subsequent tsunami last 27 February 2010, will attempt to establish the role of urban planning and design on integrating tsunami mitigation into a recovery process and how this integration may contribute or constrain different aspects of the urban quality and development of coastal settlements. This research will analyze different mitigation measures adopted by each plan based on criteria regarding five aspects of urban quality under an overall framework of sustainable development. The final aim of the analysis will be to outline recommendations to enhance or modify some measures in order to improve their performance reducing risk or improving the quality of the built environment of coastal settlements

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ACKNOWLEDGEMENT I would like to thanks many people who assisted me and gave me their support during the development of this dissertation. I´d like to thanks the support and collaboration gave by planners of PRES Pelluhue and Constitucion and the head of Department of IEUT UC to provide me information and reports of each one of the master plans analyzed. I´d would like to acknowledge to Tony Lloyd Jones for his guidance support and knowledge and to Westminster University Scholarship department for granted me with the Disaster Regeneration scholarship which gave me the opportunity to do this Master.

Special thanks to my family and my friend Angeles for their unconditional support during this whole process; I could not have done it without them. And many thanks to my classmates for their help, support and friendship, and for helping me in everything I needed.

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LIST OF FIGURES 1234567891011121314151617181920212223242526272829303132333435363738394041-

Section redevelopment plan (1974) Hilo, Hawaii Aerial images of before and after redevelopment plan of Hilo, Hawaii Building Codes for velocity Flood Zone, Hilo Hawaii Images of greenbelt before and after redevelopment plan of Hilo, Hawaii Tsunamis registered in Chile since 1835 Constitucion aerial images before tsunami 27/F 2010 Map of tsunami damages. Constitucion, Chile Map of tsunami inundation Map. Constitucion, Chile Map of restriction zones. Constitucion, Chile Map of tsunami mitigation plan. Constitucion, Chile Map of Greenbelt Mitigation Park. Constitucion, Chile.

Design for Greenbelt Mitigation Park. Constitucion, Chile Map of tsunami damages + Density. Constitucion, Chile.

Image of Constitucion waterfront beginning SXX Image of Constitucion waterfront before tsunami 27/F Map of mobility and access to Maule River. Constitucion, Chile Map of Access to Maule river and mobility proposed by PRES 2010, Constitucion, Chile Map of risk in current PRC studies 2007. Constitucion Chile.

Scheme of stakeholders involved in greenbelt implementation. Constitucion Chile.

Draw of Site Configuration. NTHMP 2001 Building Codes for tsunami resistant constructions.

Section of Constitucion before and after Norm NTM 007 2010.

Images of Constitucion. Grid - Block - Building Typoly Constitucion, Block type Before / after norm NTM 007 2010 Constitucion Urban Limits and density Constitucion Urban densification + tsunami resistant building codes PRES proposal for buildings along greenbelt. Constitucion Chile.

PRES proposal for buildings in Zone 2. Constitucion Chile.

Recommendation for building codes in Constitucion, Chile.

Map of Uses Before 27/F 2010. Constitucion, Chile.

Map of uses after Building codes and mitigation actions. Constitucion, Chile.

Pelluhue. General Context before Tsunami 27/f 2010.

Pelluhue Damages by tsunami 27/ F 2010 Pelluhue, Damaged area by Tsunami 27/F 2010 Pelluhue, Map of tsunami risk study.

Pelluhue, Tsunami Risk Mitigation Plan Pelluhue, PRC 2007 Zoning & Density.

Pelluhue, PRC 2007, zoning and population capacity.

Pelluhue. Transferring density to central area & Mobility Proposed by PRES. Pelluhue built Character before 27/F 2010 Pelluhue, Continues Facades for Tsunami risk areas.

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CONTENTS 1-

INTRODUCTION

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AIM AND OBJECTIVES

3-

BACKGROUND: a.

Chilean context post tsunami

b.

Approaches to tsunami risk mitigation

c.

Linking mitigation to urban quality improvement

4-

HYPOTHESIS AND RESEARCH QUESTION

5-

METHODS

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FRAMEWORK: a.

Strategies for Tsunami Mitigation in a Recovery Process.

b.

Defining Urban Quality criteria.

c.

International approaches integrating tsunami risk mitigation into a recovery process i. Hilo Hawaii, Downtown Redevelopment Plan.

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RESEARCH: 7a - General Context: Post Tsunami Planning process in Chilean Context.

7b - Case study: Constitucion, Maule Region. Chile.

1-

General Context

2-

PRES Constitucion,

3-

Tsunami mitigation plan and its impact in the urban quality i. Avoidance + Planned Forest ii. Building Codes + Site Configuration

7c - Case study: Pelluhue, Maule Region. Chile.

1-

General Context

2-

PRES Pelluhue

3-

Tsunami mitigation plan and its impact in the urban quality iii. Discouraging Development & Restricting Density

7d – General Discussion 8-

Conclusion

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Recommendation

10- References

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1-

INTRODUCTION When a settlement is affected by an extreme natural event such a tsunami, all the physical

components and system of a community are impacted to some degree (Geis, 1996). In order to reduce vulnerability of a community facing future events, a broad range of mitigation actions can be introduced into a recovery process, and how these actions are planned and developed can make significant difference in a community´s overall capacity to reduce these forces (Geis, 1996) and could also have a significant impact on spatial uses, directions and structure of a settlement, defining new order and relations in the entire built environment and functions of a community.

This impact may also have high effects in many aspects of urban sustainability, related to urban growth, development, density and character of the built form, but if mitigation it´s linked with broader community goals and urban improvements may become an opportunity to achieve more resilient places not just with the ability to survive to future natural disasters with minimum loss of life and property, but also with the ability to create a greater sense of place among all residents; (Valle and Campanella, 2005). This may become an opportunity not just to provide safer environments but also to improve overall aspects of urban development and urban quality of a settlement.

After last February 27 2010, when Chilean coastal settlements were hit by an earthquake and a subsequent tsunami, the National Government (2010) started a recovery process with the aim to rebuild their urban environment ensuring on the one hand, the safety of the community facing future events, and on the other, allowing sustainable development, enriching community quality of life and improving the urban quality of existing settlements (MINVU, 2010).

Based on this, to guide the reconstruction process focused on providing a safer environments improving overall aspects of urban development, different reconstructions master plans were developed for each affected settlement, which integrated for first time tsunami risk studies to the urban planning process to define were and how was safe to rebuild. Based on these studies, the recovery plans adopted two main guidelines, first, the definition of restriction zones attempting to keep developments away from high risk areas and second, the integration of tsunami mitigation measures that could allow future developments. These measures in different levels can lead to major changes in land use and construction standards that may have significant impact in the urban development and quality of coastal settlements.

In order to establish how the integration of mitigation actions in a recovery plan can impact urban areas, and how this impact may contribute or constrain to overall aspects of the urban quality and development of coastal settlements, this research will analyze: first, key issues to integrate mitigation measures into urban design and planning process. Second, it will build a criteria regarding urban quality for coastal settlements under an overall framework of sustainable development; Third, this research will analyze the measures proposed by each plan to establish the opportunities or constrains to improve their urban development, and finally this research will outline recommendation to enhance or modify some measures in order to improve their performance reducing risk or improving the built environment.

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AIM OF THE STUDY

This research will investigate the key issues to integrate Tsunami mitigation into the urban design/planning process and its physical implication on the urban structure of coastal settlements. The aim of this research is to determine how this impact can contribute or constrain to the quality of the urban environment and outline recommendations to enhance or modify the effects of the process in daily use of the urban fabric.

GENERAL OBJECTIVES 1-

Establish key issues to integrate tsunami mitigation into a planning/design process in a post disaster recovery context. Determine what the possible tools to mitigate a Tsunami are.

2-

3-

Establish the issues that link a.

Tsunami mitigation measures

b.

Urban quality improvements

Provide examples of how tsunami mitigation has been put into practice and in which ways have affect the urban quality of a settlement.

RESEARCH OBJECTIVES Considering two cases study of Chilean coastal settlements in a recovery context, the research objectives are: 1-

Establish different approaches of integrating Tsunami mitigation measures into recovery planning process in Chilean context. Determine the regulatory framework to carry out the implementation of these measures.

2-

Determine in which ways the measures proposed by each case study can impact the physical environment of these specific settlements.

3-

Establish to what extent and how this impact can become an opportunity to improve the urban quality of coastal settlements.

4-

Outline recommendation to enhance or modify the effects of these measures in order to maximize their benefits to the quality of the urban environment.

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3- BACKGROUND 3 a - CHILEAN CONTEXT POST TSUNAMI On February 27th, 2010 at 3:34 AM, a magnitude 8.8 earthquake struck the central south zone of Chile. Major tsunami waves hit the coast in the following 14 min -2h (SHOA 2010), devastating coastal villages along 600 km of coastline (Marin, A. et al 2010).

The tsunami, besides causing losses of life and destruction of property, also uncovered a lack of regulation regarding tsunami risk in the urban planning system (Andrade, B. et al 2010).

This extreme situation increased the awareness of government, community and planners to integrate tsunami mitigation into a broader reconstruction process. Based on this, Chilean Government outlined following guidelines for coastal areas reconstruction (MINVU, 2010): 1-

Elaboration of tsunami risk studies for each affected area, to determinate new zoning and land uses.

2-

Updating planning instruments of each affected community, integrating tsunami risk assessment.

3-

Implementing mitigation measures, in order to allow a sustainable development and improvement of community´s urban quality.

4-

Community preparedness and education to face possible hazards.

As a result, reconstructions master plans (PRES) were developed for each affected settlement, which integrated tsunami risk studies into the process of urban planning and design. The recovery plans based on new zoning, have evaluated and proposed actions that based on the level of risk and community needs would avoid development in hazard areas or would integrate mitigation measures to allow future developments. This, on the one side would attempt to provide safer environments in balance with the sustainable redevelopment of each community and on the other would have significant impacts on the urban environment that could either contribute or constrain to the urban quality of each settlement.

In order to evaluate in which ways these measures can modify the function of coastal settlements and how this modification can be an opportunity to improve the quality of the urban environment, would be essential to address under an overall framework of sustainable development, the following: - Key issues of integrating tsunami mitigation into urban planning process.

- Urban quality criteria to assess the impact of mitigation measures on coastal settlements.

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3 b - APPROACHES TO TSUNAMI RISK MITIGATION Mitigation is a process for disaster risk reduction, charged with planning and building the various systems and components of the built environment to minimize loss of life, damage to property from the actual event and the subsequent socio-economic disruption (Geis1996).

When the risk is a tsunami, due to its nature (low frequency, high consequences), dealing with mitigation means making trade off among competing goals (NTHMP 2001). Its implementation may have high physical impact for the affected community, therefore is essential adjusting mitigation with broader community goals, balancing uses of daily life with emergency function (UNESCO,2007).

According to NTHMP (2001) (National Tsunami Hazard Mitigation Program of United States) the most challenging aspect of tsunami risk-reduction policy remains the reduction of the exposure of coastal communities to hazard areas and keeping development at minimum. Although most of the time this is difficult to achieve due to social, political and economical pressure, it can be basically performed by three planning and design tools: land use planning, new building codes and community preparedness for emergency response (NTHMP 2001, JICA 2005).

It should be noted that no mitigation tools are responsive to all community (FAO, 2006), and not all mitigation measures are sustainable (Mileti, 1999). Some mitigation activities merely defer losses that will potentially be more devastating when they do occur, while others can result in short-term or cumulative environmental degradation. Therefore, is essential evaluating each community specific requirements to improve decision making that adopt measures with long-term results (Mileti, 1999).

Mitigation and Sustainable Development into Recovery Process After a large-scale disaster like the February 27 earthquake, there are social, economic and political pressures to enable repairs and reconstruction as quickly as possible (Bray J., Frost, D. 2010). However, the recovery process, due to disaster-created changes, may offer unique opportunities to enact policies to reduce future disaster providing physical opportunities to rebuild with more attention to safety (Petterson, J. 1999). A recovery period may also provide a chance to connect a wide range of community improvements (Petterson, J. 1999) implementing principles of sustainable development at the same time (Geis1996), understanding sustainability as the balance between social, economic and environmental health of a community (Houlihan, A. 2007). Based on this, mitigation, in order to be sustainable should provide a safer environment linked with local economic and social resiliency, viewing hazard mitigation as an integral part of a much larger context (Mileti, 1999).

To achieve long term sustainability, mitigation into the recovery process can occur during two stages: First, immediate decisions related to physical redevelopment, such as restoring streets, highway relocation, or hazard area property acquisition (Godschalk, 1985).

Second, related to long-term effects, rewriting plans, policies and regulations affecting future development in hazard areas (Petterson, J. 1999), such as, new zoning, building code supplements, and coastal setback lines.

All these actions may impact the physical system of a settlement, therefore, the role of urban planning and design is essential to make these measures work harmoniously in the daily function of the urban structure (Saunders, 2009), providing an opportunity not just to create safer places but also improving the entire urban quality of a settlement.

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3 c- LINKING MITIGATION WITH URBAN QUALITY In order to introduce tsunami mitigation into a plan, it is essential to consider the entire built environment (the block, streets, parks, and infrastructure) as a complex system. How this system is planned and developed could have significant impact on spatial uses, directions and functions of a settlement (Geis, 1996) and could define new order and relations in the built environment and its urban quality.

Although mitigation is concerned with incorporating the best hazard-resistant design available into reconstruction it must also ensure that principles of sustainable development be implemented at the same time (Geis 1996). Sustainable development in a recovery context would include projects that solve variety of community needs in order to improve its quality of life (Becker and Stauffer, 1994). If mitigation actions are integrated with other important community goals, such as, improving living conditions, public services, infrastructure, transportation and public spaces, would greatly enhance the political importance and feasibility of disaster reduction programs (Berke and Beatley 1997). Therefore, linking mitigation with broader community objectives may become an opportunity, not just to reduce risk, but also to fix or enhance existing urban patterns able to improve the urban quality of coastal settlements.

Defining Urban quality The urban quality of a settlement is understood as the ÂŤenvironmental harmonyÂť that is able to respond not only to the aspects of comfort, but also to the needs of human psychophysics and social living (Lynch, 1981).

When urban quality is related with mitigation actions in a recovery context, in order to be sustainable it should be concerned with urban interventions that provide a safer environment, achieving other social, economic or environmental goals of the community at the same time.

To understand how the impact of tsunami mitigation can improve or constrain the quality of the physical environment is necessary to asses this evaluation with some parameters associated with urban quality and sustainable development.

Lynch (1984) identifies five dimensions of the performance to judge the urban quality that can apply to the effects of mitigation in the urban environment: vitality, as the ability of a settlement to ensure the physical health and safety, sense, as the ability to rebuild a place with its own physical and cultural character, fit, as the ability to accommodate different functions and objectives of a community, access, as the capacity to improve connections, integrate areas, activities and people and control as the ability to make feasible urban interventions.

If mitigation is mainly concerned with the reduction of level of risk of a community, but at the same time it must also fit into broader urban objectives to be sustainable, these five dimensions may offer integrated criteria to evaluate the effects and opportunities of mitigation in different aspects of urban quality. These criteria will be further developed in the conceptual framework.

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4-HYPOTHESIS AND RESEARCH QUESTION In order to reduce risk of tsunami in a recovery process, dealing with mitigation means making trade off among competing goals (NTHMP 2001).

A broad range of mitigation measures can be incorporated to reduce

vulnerability of a community (Berke and Beatley) but most of the time adopting them may be hard to achieve due to social, political and economical pressure.

Although, most of mitigation measures are based on restrictions, regulations and mandatory standards that may have high impacts for the affected community, confronting many aspect of urban and sustainable development, if mitigation is integrated into broader urban and community objectives, this impact may become an opportunity, not just to reduce risk of future events but also to fix or enhance existing urban patterns able to improve the urban quality of coastal settlements.

RESEARCH QUESTION Considering two reconstruction master plans proposed for Chilean coastal settlements as case studies, I shall answer the following question: Can the integration of tsunami mitigation measures be an opportunity to improve urban quality and development of Chilean coastal settlements?

In order to answer these questions I shall also consider, -

Key issues of integrating tsunami mitigation measures into a planning process in a recovery context.

-

The regulatory framework to integrate mitigation into the planning process.

-

Possible approaches of managing tsunami mitigation and alternative measures adopted by each plan.

-

Potential implications of these measures in the components of the urban system. How this can fits, confronts or reinforces other community needs and objectives in order to improve the urban quality of each settlement.

-

Building a criteria to evaluate urban quality in a coastal context and a recovery context.

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5-

RESEARCH METHODS

A three stage research was adopted: Stage 1: Literature Review 1-

Literature review to build a framework to link: a.

Tsunami risk mitigation measures: three main references will be used to establish the integration of Tsunami mitigation into a planning process: National Hazard Mitigation Program (NHMP 2001)‘s report: Seven principles for planning and designing for tsunami hazard. UNESCO‘s guide (2008) Preparedness for cases of Tsunami and FAO´s report on Coastal Area Planning and Management (2006).

b.

Urban quality improvement: In order to assess the impact of tsunami mitigation on the quality of the physical environment. This research will build a criteria based on five dimensions of performance of urban quality identified by Lynch (1984), complemented with principles of sustainable development in a Recovery context and principles regarding coastal areas management.

2-

Secondary data to provide international examples of how tsunami mitigation has been carried out into practice in a recovery process. The literature review will be complemented by maps, and images obtained by internet sources.

Stage 2: Case Studies In order to investigate different approaches of introducing tsunami risk mitigation and its possible impact in the urban quality, this research considers master plans proposed to reconstruct two Chilean coastal settlements hit by the past tsunami 27 F 2010;Master Plan for Constitucion and Pelluhue.

The criteria of selection were based on the different levels of intervention proposed for each case and the distinctive urban pattern of each settlement.

This research will analyze different mitigation measures adopted by each plan using the conceptual framework of five dimensions to assess the urban quality.

This analysis will use maps and reports provided by each master plan, complemented also by Google Earth´s images and photographs provided by planners and internet sources.

In order establish previous community situation and needs, secondary data will be used, provided by current regulatory plans (PRC) for each settlement: Constitucion; Current PRC studies (2006). Pelluhue: Current PRC (2007).

Stage 3: Synthesis and Recommendations The final stage of the research will analyze the findings of both case studies related to the research review.

Initial research question will be revised to outline recommendation to enhance or modify Tsunami risk mitigation measures proposed for each plan, in order to improve their contribution to the urban quality.

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6. CONCEPTUAL FRAMEWORK: 6 a - Urban Planning and Design Strategies for Tsunami Mitigation Urban Planning and design can be used as an effective tool in reducing the economic and social risk of tsunami (FIG. 2006). While Planning formulates objectives and goals developing specific strategies related to land use regulations intended to improve urban safety, urban design is focused on physical structure, buildings and development within space, including building codes, design of protective structure, streets and transport.

(UN-habitat 2007).

According NTHMP (2001) that has develop seven principles to incorporate tsunami mitigation into planning and design process, in order to chose the right mitigation actions for each community and locality is essential evaluate the nature and magnitude of the risk and needs of each community. Based on this, tsunami risk is defined as: RISK: HAZARD * VULNERABILITY * EXPOSURE -

HAZARD: measures potential inundation, frequency and probability of occurrence of a tsunami.

-

VULNERABILITY: measures the features that are susceptible to damage (population, facilities, infrastructure)

-

EXPOSURE: measures the amount of development or number of people exposed to the hazard.

Mitigation can be achieved by reducing one or more of the three factors (FEMA2003).

Main outcome of this assessment are inundation maps based on tsunami technical studies to establish the vulnerability and exposure of a community.

From this assessment, communities can decide the mitigation action they can take, based on risk avoidance strategies that are premised on proactive land use planning that guide development from hazardous areas (Berke and Campanella 2006) or on risk reduction that foster development in high risk areas providing mitigation infrastructure. Main recommendations to integrate tsunami mitigation into planning and design process can be grouped into three planning and design tools: land use planning, protective structures and building codes and community preparedness to face future events (NTHMP 2001, FAO, 2006, JICA 2005): 1-

Land use planning: This guides the location, and intensity of development to reduce the community exposure (NTHMP 2001). It limits expansion into hazard areas through avoidance or restricts density of development.

AVOIDANCE: keeping people away from hazards (Mileti 1999). Is the most effective measure but hard to implement due to political, social, and market pressure (Spangle, 1991).

RESTRICT DENSITY: through large lot zoning, reducing plot ratio, financial incentives, high insurance.

2-

Protective measures: are utilized in site planning to modify the force of waves to protect development. These strategies can be carried out through an engineered approach such as: breakwaters, seawalls and dykes, or a natural approach such as: coral reefs, sand dunes, planned forest and wetland (FAO, 2006). This has been a more feasible option for Chilean cases.

Building codes and Site Configuration: Establish minimum design standards to protect structures from collapse (NTHMP 2001). A tsunami resistant building should address forces associated with water pressure, buoyancy, currents and waves, debris impact, scour, and fire. And the configuration

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of new subdivision can reduce tsunami damage providing maximum space between buildings and elevating building above inundation levels; 3-

Community preparedness, evacuation plan: The primary strategy for saving lives is to evacuate people from the hazard prone areas through horizontal or vertical evacuation. The evacuation plan is an integrated network of evacuation routes which provided the fastest access to shelter zones or safe areas (IEUT UC 2010). This system depends on the local street network and topography.

According to the FAO´s (2006) Report, most of the time mitigation strategies are hybrid approaches that combine a number of measures to maximize benefits while addressing the unique needs of each community.

This can be seen in the following section (Fig 1), proposal for Hilo, Hawaii, downtown redevelopment plan (1974) which integrates a combination of tsunami mitigation measures to guide development in tsunami risk areas.

1 Urban planning and design for tsunami mitigation in Hilo, Hawaii, redevelopment plan (1974). Adapted from NTHMP 2001

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6 b - Urban quality of coastal settlements in a recovery context.

In order to assess the effects, opportunities and constrains of tsunami mitigation into different aspects of urban development, this research will developed a criteria based on five dimensions to judge functions and quality of the urban environment identified by Lynch (1984), which must be understood in the context of coastal location, regarding specific issues of sustainable development in a recovery Context.

Urban quality in a coastal context When urban quality is related to coastal settlements it should be concerned with the whole network of places and functions between the coast and the city (Carta 2006) and with the special condition of coasts on their socio-economical role, their environmental character and its vulnerable nature as high risk areas.

FAO´s report on Integrated Management of Coastal Zones (Clark 1992), outline principles related to the special character of coast that can be taken into account for urban quality improvement: 

Principles related to the public nature and character of the ocean and coast, which are concerned with public access as a prerequisite to allow intensive uses activating economical and social role of coast.



Principles related to the environmental nature of the coastal zone, concerned to secure the quality of the coastal ecosystem and limit the exposure to natural hazards.



Principles related to management of coastal space focused on proper uses and public participation.

Urban quality and sustainable development in a recovery context Reconstruction may provide opportunities for communities to rebuild better than before and to enact policies to reduce future risk, introducing mitigation actions with long term view that ensure that principles of sustainable development be implemented at the same time (Geis, 1996). Sustainable development in a recovery context has been described as those initiatives able to improve community quality of life that promote (Berke and Beatley, 1997): 

Economic development that foster local activities.



Recognizes ecological limits and enhance the capacity of the ecosystem



Improve distributional equity



Prevent or minimize harm to others and foster local resiliency



Promote participation among all stakeholders

When urban quality is part of a recovery process, it should integrate risk reduction measures that respect these principles and are linked with broader community goals that promote sustainable development. This means that to achieve urban quality in a recovery context any intervention should include ―multipurpose recovery projects‖ that solve a variety of problems (Becker and Stauffer, 1994) and allows communities to integrate mitigation into day-to-day functions (Geis, 1996).

In order to integrate tsunami mitigation that improve urban environment and support Sustainable development of coastal settlements, the five dimensions to judge the urban quality should consider the following issues:

:

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1-

Vitality: as the ability to ensure the physical health and safety.

In order to be sustainable mitigation should reduce community vulnerability to tsunami risk, adopting measures that recognize ecological limits and enhance qualities of local ecosystem.

2-

Sense: as the ability to rebuild a place with its own physical and cultural character It should integrate mitigation actions that enrich identity, character and function of the existing urban and social fabric.

3-

Fit: as the ability to accommodate different functions and objectives of a community This is a main points to achieve sustainability, where mitigation should be linked and support broader community objectives, such as promoting economic development, enhance touristic resources or fix previous community problems.

4-

Access: as the capacity to improve connections to integrate areas, in an equity level for all people.

Mitigation actions should provide and enhance public access to the coast, promoting intensive uses in public space. Also should be concerned with improving movement and connections, key issue in a recovery context.

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Control: as the ability to make feasible urban interventions.

It should be concerned with an efficient management framework to ensure durability, implementation and feasibility of mitigation actions. In order to be sustainable it should select mitigation strategies that evolve from participation among all stakeholders (Miletti, 1999).

The criteria developed above may offer a useful framework to assess how mitigation actions can be planned to reduce level of risk addressing principles of sustainable development and improving the urban quality of coastal settlements at the same time.

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6 c - Approaches on integrating tsunami mitigation – international experience Hilo Hawaii, Downtown Redevelopment Plan 1960 Hilo, the largest settlement of Hawaii, is a clear example of how tsunamis have had a profound effect in its urban shape (SDAT 2009). Hilo has been hit by 25 tsunamis since 1812. The most devastating ones occurred on 1946 and 1960, destroying significant areas of city centre (county of Hawaii 2010).

After 1960, a series of redevelopment plans were adopted subject to new urban design, building design standards and land use patterns to mitigate the effects of future events (NTHMP 2001).

Some Mitigation Measures adopted by the Plans have been the following: 1-

Land Use Planning: AVOIDANCE+ PLANNED FOREST

After 1960, local government enacted a policy for a coastal construction setback line, forbidding development in recent tsunami inundated areas (Fig 2). The ocean side buffer zone was expanded, raising the inland construction border to 8m above sea level (NSTC, 2005). In 1979, Hawaii County adopted a policy to create a forested greenbelt along the coast. The dense vegetated buffer was a multipurpose plan. A string of parks and trails were developed to provide protection against storms and future tsunamis providing multifunctional public, recreational and memorial spaces, becoming an important site for community activities (FAO 2006).

This measure redefined a new structure and function of the city, relocating residential and commercial activities to new center upland of the old town center to stimulate the rebirth of the city (FAO 2006). The relocation of businesses

and

individuals

was

granted

with

tax

benefits

(SDAT

2009).

2 Hilo before - after 1954. A setback line policy to expand the buffer zone. The damaged area was designated as a public park, and commercial centre was transferred to safer areas inland.

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2-

Building Codes:

Hilo Redevelopment plan (1974) and subsequent policies such as the Storm Management Code (2008) have established the Velocity Flood Zone based on previous tsunami inundation. This requires that all development in the safety district is subject to urban design and building design standards. Any structure below the 6 m (fig 3) elevation was required to be designed to withstand the force of a major tsunami (NTHMP 2001). New construction and major renovation require raising the first habitable floor up a story and ground floor was designated to use parking structures as protective barrier from a tsunami for inland structure (SDAT 2009).

3 Building Codes for velocity Flood Zone, Hilo Hawaii. Adapted from NTHMP 2001

3-

Community Preparedness:

After 1946´s Tsunami, Hawaii County established an advance tsunami warning system. In 1963 a tsunami inundation map was developed. This was used to developed an evacuation plan, focused on education and strong development of tsunami signage in strategic points around the city that serve as an educational tool as well as physical reference point. An important element for community awareness is tsunami memorials as part of public daily space.

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Tsunami mitigation and its impact in Hilo´s urban quality Avoidance through the setback line policy enacted after 1960 tsunami, even though has profound impact in Hilo´s urban structure, has also contributed to many aspect of urban quality.

In terms of vitality the main contribution of avoidance is keeping away development from hazardous areas.

The greenbelt forest, although it doesn´t provide 100% protection against tsunami (FAO, 2006) contributes to the environmental protection of the water and natural species (SDAT 2009).

In terms of access, the designation of the damaged area as Public Park has provided broader public access to the waterfront, creating a recreational space with equal access for the whole community and where the open space is also considered to be the visual connection between the town and the bay (FAO 2006) (fig 4). As Hilo´s government (SDAT 2009) states this is a contribution to their sustainability as it builds a mutually supportive, dynamic balance between social well-being, economic opportunity, and environmental quality.

4 HIlo before -after 1960. Greenblet park provides Public access to waterfront enhancing natural character.

According to local government sources (2010), the public park has also contributed to the sense of the place enriching existing natural and green character of the context that has become a strong touristic attraction. On another hand, in spite of its contribution, the setback line has affected many historical buildings (SDAT 2009) disrupting the character of downtown architecture.

In terms of fit; the relocation of commercial activities creates a new center with new connections inland.

Around this center was initiated the development of the University of Hawaii Campus at Hilo, which was a new motor of development for the area.

In order to control or implement these measures in Hilo´s context have been essential: 1.

Technical inundation map to guide land use, building standards and insurance maps.

2.

A land bank as a county fund for acquisition of land in hazard areas to allow the preservation of open space (SDAT 2009).

3.

Enact local policies as the setback line policy after 1960 tsunami, the Storm Management Code (2008) and building codes provided by 1974 Redevelopment Plan (1974).

Building codes (1974) on another hand, although are meant to protect the public from tsunamis and to reduce the burden for taxpayers (SDAT 2009), they present many constrains to sustainability and urban quality. The major economic function of these buildings is ground floor retail (SDAT 2009), if they are forced to raise the first habitable floor, its economic function is disrupted. Also, most of buildings affected by the velocity inundation zone are historic buildings that contribute to the sense and character of the existing settlements.

Interestingly, the storm management code (2008) allows a variance for historic buildings to avoid raising first floor. These buildings have to follow Secretary of Interior Historic Preservation Guidelines (SDAT 2009).

23

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7. FINDINGS 7 a - Chilean Context Post Tsunami According to tsunami risk studies for O´higgins and Maule region (IEUT UC 2010), Chile, with 4.200km of coast, located in subduction zone of Nazca Plate; has historically registered in the last 175 years 75 tsunamis of different magnitude. The central area (V, VII, VII, VIII region) affected by last tsunami has experienced 17 of these. Tsunamis with waves higher than 5m have occurred every 29 years and greater than 10m as last tsunami (27 F 2010) every 88 years (IEUT UC 2010) (fig 5).

5 Tsunamis registered in Chile since 1835. Adapted from IEUT, 2010 In spite of this activity, before the earthquake and subsequent tsunami of 27/ F 2010, Chilean regulatory framework didn´t consider risk of tsunami as part its planning process.

After this, the regulatory framework integrated the concept of tsunami to the definition of ―risk area‖ in the article 2.1.17 of the O.G.U.C (2010), which states that: ―Regulatory plans could restrict urban development in ―risk areas‖, defined as those areas in which, after proper studies and investigations, constitutes a potential danger to human settlements‖. Development in these areas would be allowed under the integration of engineering or other measures sufficient to mitigate hazard effects‖ The main outcome of this law is carrying out geological tsunami risk studies that define risk maps for each affected settlement that base on the level of risk designate three zones (MINVU 2010): 1) Restriction Zone1 which avoid all developments and allows uses like green, recreational and public space, marine infrastructure, and commercial and productive activities.

2) Restriction Zone 2; is an area that allows residential and commercial uses subject to mitigation measures, building code standards and evacuation plan. This area excludes Critical facilities.

3) Zone 3 out of risk, allows all uses that current regulatory plans permit.

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From this new zoning Central Government (2010) has launched a Tsunami Protocol based on: 1.

Updating planning instruments of each affected settlement integrating tsunami risk assessment.

2.

Implementing mitigation measures, in order to allow a sustainable development and improvement of community´s urban quality.

3.

Community preparedness and education to face possible hazards.

Regulatory Framework to integrate Tsunami Risk The regulatory framework to implement these guidelines in Chilean context is based on norms dictated at national level through ―The General Law of Urban Development and Building‖ (O.G.U.C..) and local planning instruments called Regulatory Plans (PRC), which are more directly involved in actual land use decision making (Andrade et al., 2010). According to Andrade et al. (2010), many coastal affected areas, or either didn´t have these instruments or they were created more than 20 years ago, therefore they need to be update in order to integrate tsunami risk and adapt ongoing urban changes.

On another hand, building codes standards to resist tsunami forces have been integrated in a new norm NTM 007- 2010 that is under study to be approved. The norm would consider minimum design standards to protect properties from structure collapse. Main considerations of the norm would be: ―Avoiding residential uses in floors under tsunami inundation level, designing structure to resist water force and organizing a site configuration that allows water flow between buildings.

While laws and regulatory plans (PRC) are subject to updating process, central Government requested Reconstructions Master Plans (PRES) for each affected settlement to outline recommendation for futures PRC. Regarding tsunami, these plans have evaluated and proposed different approaches to integrate tsunami risk into the planning process in order to provide safer environments.

The following research will analyze how different tsunami mitigation approaches proposed by two of these master plans (PRES) can impact the urban structure of each settlement, contributing or confronting sustainable development and improvement of their urban quality.

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7 b CASE STUDY I: CONSTITUCION, VII REGION, CHILE. 7 b. 1 - General Context: Constitution is the biggest coastal city of Chilean VII region, located next to Maule River, with a population of 51.409 people (INE 2010). According to council source (2010) its main features are its natural landscape formed by the river, the beach and coastal mountain that give a touristic character and a regular built form conform by a regular grid from Spanish foundation in 1794, with traditional architecture with continues facades (Ramirez, J.2010) that give form to the block (fig 6). Main economical activities until mid 60s were based on the fluvial port, shipyards and forestry industry. According to Current PRC studies (2006), after the port was closed in mid 70s, main economic activity became the forestry industry with CELCO wood pulp, which involves the 21% of working force of the community. As main beach resort for the region, the touristic activity take an important place in the economy, commercial activities and artisanal fishery on its side represent important income for permanent residents.

6 Constitucion, before tsunami. The regular grid it´s surrounded by natural landscape: Maule River, Pacific coast, Coastal Mountain and Pine forest. Source: googlearth, Panoramio,

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According to National Statistics Institute (INE) sources (2010), Constitution, due to its location near the mouth of Maule River, was one of the most damaged cities hit by the Tsunami. 60 people died and 8.239 people lost their homes. 80% of the buildings were harmed, with the 2.989 properties (34% of urban area) in low-lying areas within a few hundred meters of the river sustaining the highest damage. (Bray J., Frost, D. 2010). 80% of i

tourism industry was made inoperative and the 83% of commercial facilities were destroyed (fig 7)

7 Map of tsunami damages. Source INE 2010. Inundated area covers 34% of urban area

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7 b. 2 - PRES Constitucion To carry out the reconstruction process including tsunami risk information to guide a safer redevelopment, it was required PRES Constitucion, a Master Plan developed by ELEMENTAL and ARUP studio, in agreement with MINVU, ARAUCO Company and Constitucion Council.

Taking the opportunity of building back better, according to PRES‘s report (2010) the main guidelines outlined by the plan address previous community lack and problems, which are associated to river flood control, housing demand, urban limit expansion and transport system congestion due to CELCO trucks. Also community demands are based on lack of employment, the limited public access to the river waterfront; the lack and poor quality of public space and, after the tsunami the main community demand was building back in a safer context.

According to this evaluation, the plan has integrated tsunami risk as one of the main priorities to guide the proposal, but due to a low frequency of tsunami events (last 1835 and 1906 in Constitucion), mitigation measures are on a constant trade off with other community objectives such as; promoting economic rehabilitation based on tourism reactivation, recovering the coast and river waterfront as main natural touristic assets, improving infrastructure and movement system and solving an increasing problem of housing demand.

7 b. 3 - Tsunami Mitigation Plan In order to integrate mitigation actions and to establish where was safe to allow redevelopment; the Geo-PUC (2010) carried out modeling based on last tsunami information as worst scenario. This modeling defined a maximum wave high of 7 to 12m on the urban area, with a velocity of 4m/s, and a depth of inundation of 4m high in the borders and up to 2m in urban centre. The extension of the inundation is given by 10m high that defines the safe area. This is slightly higher than last event experience, where inundation extended for 10 blocks long and 3 to 4 blocks inland from the riverfront (Bray J., Frost, D. 2010) (fig. 8).

8 Constitucion Tsunami inundation map. Source: Geo-UC 2010

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Based on in these studies (Geo.PUC 2010), the definition of 10 m high as worst inundation scenario, covers almost 65% of Constitucion urban area, and last tsunami inundation covered 34% of urban area and affected 2989 properties (fig. 7). In order to allow redevelopment based on certain degree of plausibility and feasibility (Petterson, J. 1999), central government defined a narrower zone as ―High risk area‖ (Zone 1) which restricts residential development and is subject to mitigation actions that would allowed development in zone 2 (fig 9)

9 Map for restriction Zones in Constitucion. Adapted from MINVU 2010.

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To carry out redevelopment in Zone 2 PRES has proposed following mitigation actions (fig. 10): 1-

Restriction Zone 1: AVOIDANCE + PLANED FOREST: Greenbelt mitigation Park.

2-

Restriction Zone 2: BUILDING CODES - Tsunami resistant Construction.

3-

Zone 1 + Zone 2 : EVACUATION PLAN: network of evacuation routes and safe Points

10 Constitucion tsunami mitiagtion plan. Adapted from PRES 2010.

As it has been state previously, mitigation action may have high impacts in urban areas and may constrain specific aspects of urban development; therefore main challenge for mitigation plan is providing safer standards that minimize the disruption of community development. Also linking mitigation to a wide range of community improvements (Geis, 1996) may enhance its feasibility and their impact can become an opportunity for further urban improvements.

To establish to what extent these mitigation actions can enhance or confront other community needs, to improve or constrain the urban development, will be the core of following analysis.

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7 b. 3 i - Avoidance + Planed Forest: Greenbelt Mitigation Park New zoning designated the first row of blocks along the river as ―High risk area‖ or zone 1 (fig.9), that on the one hand, enforced avoiding residential development and critical facilities and on the other requires mitigation actions to allow development in Zone 2. Based on this, PRES (2010) designated this area as greenbelt that with a planned forest would act as buffer zone. Even though, the creation of the greenbelt is based on tsunami safety purpose, it is a long term measure with long term results. Therefore, to make it feasible, PRES (2010) proposes to address multi - community objectives such as controlling flooding risk, providing public access to the river waterfront and providing green infrastructure as main public space for the city.

11 Greenbelt Mitigation Park. Adapted from PRES 2010.

Due to its dimension, spatial condition and residential restrictions, the greenbelt is a measure that can modify important components of the urban structure having significant impact in the community and urban development.

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Role of Greenbelt Mitigation Park on urban quality Vitality: The ability of the greenbelt on providing a safer environment is based on two objectives: First, acting as buffer zone, widely recognized as a natural method to mitigate tsunami forces through coastal vegetation. Although the vegetation barrier cannot completely stop a tsunami and the mitigate capacity of a planned forest is hard to prove due to limited data are available (Tanaka et al,2009), according to FAO´s information (2008) its main role are 1) Energy dissipation of water flow velocity and pressure 2) trapping effect to stop debris 3) escaping effects to provide life- saving.

The effectiveness of planned forest depends on tsunami characteristics such us wave force, length and direction (e.g., Shuto [1991], Harada and Imamura [2003], Tanaka [2008]) and also on the age and structure of the forest (width, vegetation density, vertical structure and forest shape) (Tanaka, N. 2010). On this matter forest width is a fundamental factor in mitigation (FAO, 2008). As many studies reveal (IEUT 2010) for waves up to 3m, forest need a width of 20m but for waves higher than 6m, the width should raise to 100m. Based on this, a contribution of the greenbelt is providing an average width of 85m (fig. 12). Also as a natural method it would support sustainable principles, enhancing environmental quality of natural ecosystem. Is essential to highlights the fact that proper planning and management of vegetation are required to maintain the tsunami buffering function of coastal forests (Tanaka, N. 2010).

12 Design for Greenbelt Mitigation Park. Source: PRES 2010

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The second objective is keeping away the most exposed population from tsunamis risk. Although the area affected by last tsunami is bigger than the greenbelt (fig. 13), avoiding development of the whole area it would have high social and economic costs, affecting 29% of the population and 34 % of the urban area (INE 2010).

The designation of a narrower ―high risk area‖ is based on certain degree of feasibility, due to the high level of damaged of these properties, the low density developed by these blocks, and the low population involved (fig.

13). Main drawback of this measure is enforcing the expropriation of 159 families, but it´s meant to provide mitigation to allow development for 2.989 other properties and the whole city.

13 Map of damages. Adapted from INE 2010

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Access and Character According to council sources (2010), the relationship between Constitucion and Maule River has been historically recognized as one of its main natural assets. This used to give character and identity to the city since its foundation as Fluvial Port and as historical touristic resort where coastal and river waterfront used to be a continuous public promenade that enjoyed the natural landscape context (Ramirez, J.2010) (fig. 14). The relationship between the city and the river was changed after the Fluvial Port was closed and this land was privatized (Council source 2010) (fig. 15).

14 Constitucion, beginning SXX. Historical relationship between the city and the river. Source (el Maulino Journal)

15 Constitucion Before Tsunami 27/F. Source PRES, 2010

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Before last tsunami (27 F), this relationship hardly existed being mainly blocked by low density residential development allowed by current land zoning (1987), which has also designated the public access to the river to a stripe of 10m wide between the highest tide lines to private property, distance that can hardly build an urban relationship and interrupts the continuity and public character of the coast and river waterfront (fig 16).

On another hand, due to this limited relationship, and on the hierarchy of the west access to the city, the transport movement has been concentrated inside of the urban area, CELCO trucks, Public transport and touristic transport share the same infrastructure situation that creates congestion problems and focuses development just in the city center (fig 16).

16 access to the river and transport mobility before 27/F 2010. adapted from PRES 2010

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After the tsunami, the designation of ―high risk area‖, leads to apply the expropriation law 2.186 which allows the government to acquire land for national and public benefit. This area as State-owned land designates 80 m of protection from the highest tide line to public property (fig 17), which has been designated as buffer zone for public uses. This becomes the main change in the urban structure and a main opportunities to contribute to urban quality; first, as it has been recommend on FAO´s report (1992), it recovers the public access to Maule River waterfront, builds the continuity of the coast and riverside promenade, and integrate physically and visually the city center with natural landscape features, that as it has been recognized by the PRES´s public consultation (2010) brings back an historical natural asset that enhance the touristic character of the city, promoting its second economic activity.

Also the open access to the river and the continuity of the green belt will give hierarchy to a new axis which will bring the transport movement along this open space, decongesting the city center. This would enhance the south access of the city, differentiating CELCO track movement of the west from the touristic movement along the river; this would promote a new mix uses center with touristic character and would enhance the pedestrian relationship of the city with the riverfront (fig.17).

17 Access to the river and mobility proposed by PRES 2010

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Fit: according to several recommendations (Becker and Stauffer, 1994), sustainable redevelopment in a recovery context should include multipurpose projects that solve a variety of problems that would enhance social and economic feasibility of mitigation programs. On this matter, the Greenbelt is planned to addresses one of the Constitution´s most frequent problems related to the overflow of Maule River due to its shallow condition when meets the sea. According to current PRC studies (2007) this has affected historically an extension of four blocks inland that experience problems of flooding every two years, similar extension reached by last tsunami (fig 18).

Addressing this problem, has been on government agenda since 2004 which has allocated US$ 12 MM for Maule River flood protection, but the project hadn´t been carried out before the past Tsunami. On this matter, the greenbelt´s main contribution would be providing enough space to implement natural solutions, working with topography to fill and lift the ground to contain the flood of 25 years worst scenario. A flooding park could also act as wetlands which through friction can provide protection against future tsunamis (FAO, 2006).

According to PRES (2010) ´s sources, the implementation of the greenbelt on the river area would need an investment of US$ 9.3MM. As it has been discussed (see Becker and Stauffer, 1994, Mileti 199, Geis, 1996), As it has been discussed (see Becker and Stauffer, 1994, Mileti 199, Geis, 1996), linking this measure to previous government plan and community improvements, would greatly enhance the political importance and feasibility of this mitigation program

and would strengthen social acceptance of

expropriation.

18 Map of risk in current PRC studies 2007

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Control: Greenbelt implementation and management to be feasible must become integrated with overall institutional process associated with Reconstruction and coastal management.

The recovery process presents three opportunities to implement the greenbelt project: -

The definition of ―High risk areas‖ (article N°2.1.17 O.G.U.C) leads to apply the expropriation law 2.186 which allows the government to acquire land for national and public benefit designating the area for green and public spaces as main uses.

-

Updating of planning instrument (PRC) to integrate new zoning and land uses. A post disaster context enables to apply the law of seismic and catastrophes (Law 16.282) that allows modifications to current regulatory plans (MINVU 2010)

-

The recovery process is also an opportunity to integrate institutions and stakeholders to make more efficient the process of implementation. An example of this according to PRES (2010) sources is that the greenbelt already counts with funding approved for its implementation.

Some responsibilities involved are (fig 19):

19 projects, planning instruments and stakeholders involved in greenbelt implementation. Own elaboration

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7 b. 3 ii - Building codes - Site Configuration Based on MINVU (2010) requirements, development in Zone 2 would be allowed if it´s subject to mitigation actions; such as the greenbelt as buffer zone and the application of building codes standards and site configuration for buildings to resist tsunami forces.

For site configuration, literature recommends (see NTHMP 2001, FAO 2006); restrict density in hazard areas, provide maximum space between buildings and elevate building above inundation levels to allow flow of water (Fig 20).

20 Site Configuration. source: adapted from NTHMP 2001 Related to buildings and construction, MINVU (2010) is studying a norm (NTM 007 2010) to integrate tsunami resistant standards to buildings located under tsunami inundation level. Main considerations of the norm are related to (fig 21): 1-

Building structures must addresses water forces of pressure, buoyancy, currents and wave‘s impact and scour.

2-

Habitable space in buildings must be elevated above inundation level by structure such as concrete or metal piles, piers or shear walls parallel to the direction of the wave, with deep foundations to resist scour and erosion

3-

Spaces under inundation level can have non habitable uses (commercial, retail) if structure allows the flow of water or provide hermetic structure resistant to tsunami forces.

4-

If buildings are provided by efficient evacuation systems and major mitigation measures, spaces under inundation level could be habitable.

21 Building codes according to NTM 007 2010. source: adapted from NTHMP 2001 Even though the norm hasn´t been yet approved, PRES Constitucion (2010) has proposed similar standards for buildings under inundation level. Although building codes have a safety purpose, they may have many implication in uses, cost of construction and configuration of the urban structure, having significant effects on Constitucion urban development and quality.

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Impact of building codes on the urban quality Vitality: To define building codes is essential to estimate tsunami intensity. Considering last event information, Constitucion urban center experienced waves up to 7 to 12 m and an inundation depth of 2m. This would define according to the norm (NTM 007 2010), that buildings in zone 2 should keep maximum distance to allow the flow of water, should avoid residential uses on ground floor, and structure should be design to stand the water force without being move off their foundation (fig. 22). The mitigate capacity of this configuration, as it´s explained by the norm NTM 007 2010 and by NTHMP (2001), is based on; mitigate the force of wave by friction, avoiding the collapse of buildings to minimize floating debris that can damage nearby buildings and people. However, It should be noted that they don´t save lives, so is still essential efficient evacuation system and major mitigation actions. It´s essential as well to inform and enlighten individual property owners about the risk they face and the mitigation actions they can take (Mileti 1999). On this matter insurance incentives could be an alternative tool to engage individual property owners on risk reduction programs.

22 Section of configuration according to norm NTM 007 2010. Source: own elaboration.

According to the norm, to design tsunami-resistant construction will be required qualified architects and engineers and proper construction inspection to ensure building codes follow appropriate standards. This, plus the needs of the structure upgrading; will elevate the cost of new buildings construction. Although Central government is providing an extra subsidy of 150 UF (US$ 6840) for tsunami resistant constructions, in most cases the cost will raise above this amount.

In spite of its mitigate capacity, building codes may constrain aspects of urban development regarding high cost of construction, restriction on residential uses, and effects on historical architectural character as it has been shown on Hilo´s experience. Therefore, is essential carrying out major mitigation measures such as the greenbelt to reduce tsunami effects on major developments. This would allow according to the norm adapting codes standards at feasible level and local reality.

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Sense: Building codes required by the norm NTM 007 2010, would have significant impact in the character and uses of Constitucion´s urban center; which according to current PRC studies (2006), it´s characterized by a regular grid formed by blocks of one to two stories high with continuous facades and many heritage buildings from SXIX, that although, many have been damage by previous earthquakes, the city still keeps its main feature of grid -block structure (fig 23).

23 Constitucion. Grid - Block - Building Typoly

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Physical changes generated by building codes, would be based on distance between buildings and on the elevation of habitable spaces which could leave empty spaces in ground floor or will force alternative uses, constraining the street configuration of continuous facades, losing the regular grid - block physiognomy that according to PRC studies (2006) gives character to the street and public realm (fig. 24). Buildings with heritage value may have special considerations to protect their character as it has been practiced in Hilo downtown, preserving historic and symbolic buildings is important to retaining community identity (Petterson, J. 1999).

Tsunami resistant standards can be achieve by retrofitting the current structure adapting to tsunami and earthquake standards at the same time as it is recommended by NTHMP (2001).

24 block type Before / after norm NTM 007 2010 MINVU (2011) has already assigned 2.524 subsidies for housing reconstruction, as many of them would rebuild their properties individually, new PRC will need to provide guidelines to apply mitigation techniques, following specific height and lines, in order to keep a sense of continuity of the block respecting existing urban patterns.

Densification Model On another hand, instead of building individually, PRES (2010) proposes housing densification in Zone 2, to address previous problems of urban growth and housing demand. According to current PRC studies (2006) and INE information (2010), since 1987, Constitucion has experienced a growth of 49% its population (from 34.341 to 51.409), and housing demand is expected to increase on 60% by 2022 (from 10.103 to 16.444). Due

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to a lack of urban land, this growth has extended the urban limit (current PRC 1987) towards the hills without adequate urban infrastructure (fig. 25).

25 Constitucion Urban Limits and density Considering this demand and lack of urban land, PRES (2010) proposes models of ―lots fusion‖ of damaged properties to increase density on larger lots. This is supported by a new subsidy for urban densification launched by MINVU (2011)ii which aims are; regenerating damaged urban centre and controlling urban extension with a balanced density (max 5 stories high), achieving a compact city as one of the concept of sustainable growth (fig 26).

26 Urban densification + tsunami resistant building codes

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This may have contradictions with main recommendations of avoiding development or restrict density on areas at risk (NTHMP 2001, FAO, 2006, UNESCO 2008). As Berke and Campanella (2006) state, these measures are based on ―risk reduction‖ rather than ―risk avoidance strategies‖, which involve fostering high risk development through major mitigation measures that may not always provide protection from powerful hazard events. However, due to the low frequency of tsunami events in the area (last 1835 and 1906) and the designation of the greenbelt as buffer zone that PRES and MINVU (2011) propose increase development.

Based on PRES (2010) proposals, it seems interesting how densification models integrate mitigation techniques keeping a sense of continuity of blocks and grid character of local urban configuration.

Buildings along the greenbelt of 4 stories high would designate ground floor for commercial uses with a structure of concrete walls parallel to wave direction and concrete pillars that would generate friction to slow the wave velocity (fig 27). Buildings in Zone 2 of 3 stories high, would keep distance for parking lots that allow the flow of water (fig.28).

27 Buildings 4 stories high along Greenbelt. Adapted from PRES Constitucion 2010

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28 Buildings in "Lots Fusion" Zone 2. Adapted from PRES Constitucion 2010 Nevertheless, would be essential for developments to consider efficient evacuation plan, horizontal routes or vertical evacuations structures, and high building codes standards to stand the force of possible events (fig.

29). It also would be recommended for zone 2, flexibility for residential uses on ground floor in order to adapt to local needs and reality as an important principle to achieve long term sustainability.

29 Recommendation to building codes. Adapted from PRES Constitucion 2010

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Fit: The application of building codes in zone 2 specially the elevation of habitable spaces would modify uses and activities of ground floor. The actual uses allowed by the current PRC (1987) for centric area are housing, facilities and commercial activities. According to PRC studies (2006), main commercial uses (16% of Constitucion economic activities) are concentrated in central streets along town square and the rest of the area is mainly residential (fig 30).

30 Map of Uses Before 27/F. source: own elaboration based on current PRC studies (2006)´s information Forbidding residential uses on ground floor, on the one hand may become an opportunity to reinforce the new mix uses axis along the greenbelt with activities related to tourism such as, hotels and restaurants which represent today just the 2% of the economy. This can detonate economic diversification and urban regeneration, leading to an overall improvement in the business climate (Spangle, 1991) essential for sustainable reconstruction (fig 31).The consolidation of this area will depend on; spatial guidelines to ensure harmonic development, and on an integrated management system able to promote investment and partnership iii

business. On this matter a BID (business improvement district) model can be useful to work in partnership where business can invest collectively in local improvements to enhance their trading environment (www.chambers.uk 2011).

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31 Map of uses after Building codes and mitigation actions. Source: own elaboration based on current PRC studies (2006) Although, new configuration may be an opportunity for the new greenbelt axis, for the rest of zone 2, where the uses are mainly residential may force alternative uses, or either forbidden by current PRC (1987) for the area, or commercial uses without enough demand to support the activities. Based on this, building codes should consider certain degree of flexibility to allow residential uses in ground floor, if higher mitigation or evacuation standards are provided.

Control: The implementation of the building codes will depend on certain degree of feasibility through: 

Economic facilities: MINVU (2010) is providing a subsidy for reconstruction on own site (460 UF + 75UF: U$24.000) and an extra subsidy of 150 UF (US$ 6840) to include tsunami resistant standards. NTHMP (2001) also recommends applying economic incentives to owners, such as reducing property taxes, low interest loan and waiving of permit and inspection fees.



Efficient Management to carry out housing densification models that include building codes standards. It will need an Urban Development Enterprise (EDU) to coordinate investment, property owners, land acquirement, subsidies and permits.



Guidelines: new PRC should provide architectural and urban design guidelines such as height, setback lines, ground floor uses, to apply mitigation techniques in order to keep value of local urban configuration.

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

Flexibility: New PRC should have special considerations with historic buildings to ensure that mitigation techniques don´t disrupt identity and urban character, as it has been practiced in Hilo downtown redevelopment, these buildings have to follow Secretary of Interior Historic Preservation Guidelines.

Flexibility should be also applied to allow residential uses on ground floor, requiring higher standards of warning system and evacuation infrastructure.



Awareness: it´s essential keeping aware individual property owners about the risk they face and the mitigation actions they can take (Mileti 1999). On this matter insurance incentives could be an alternative tool to engage individual property owners on risk reduction programs.

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7 c - CASE STUDY II: PELLUHUE, VII REGION, CHILE. 7 c. 1 – General Context In order to present a different approach integrating tsunami mitigation into a smaller settlement on Chilean context, this research will review the case of Pelluhue, a rural beach resort located at south of Maule region part of the southern coastal route, characterized for its natural surrounding conformed by the beach, Curanilahue river and coastal Mountain (fig 32). According to current PRC (2007), Pelluhue is a district of 2827 people which has experienced a high demographic growth of 27% in last census period (1992-2002).

This has extended the urban limit in a linear growth due to a geography limited by coastal Mountain. As a beach resort, main economical activities are based on tourism, retail, restaurants and hotel (23%) and a main feature it´s a summer floating population that increases almost three times (6.176) representing a 64% of total housing (1123 out of 1767). In spite of its economical contribution, this also represents Pelluhue´s major problems of transport congestions, water supply and unemployment during the year.

32 Pelluhue. General Context Before Tsunami 27/f 2010. Source: Google earth and Council website images.

According to INE sources (2010), Pelluhue, was highly hit by 27F 2010 tsunami, where 47 people died, 679 (24%) lost their homes and 35% (628) of housing was destroyed (the densest area in Pelluhue); although most of them are holiday houses this has a high impact in the economy (OIT 2010). On this matter the most affected economical activity would be tourism and commercial facilities that suffered 40% of damaged (Fig. 33- 34).

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33 Pelluhue Damages by tsunami 27/ F 2010. source: INE 2010

34Damaged area by Tsunami 27/F 2010. source: PRES 2010

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7 c. 2 - PRES Pelluhue 2010 PRES Pelluhue developed the Reconstruction Master Plan between MINVU, Pelluhue Municipality, Institute of Urban studies of Catholic University of Chile and ―Un techo para Chile‖ Foundation.

According to PRES (2010) beside reestablishing community normal function focused on safety, as same as in Constitucion, the plan takes the opportunities to address previous community needs, mainly; the growth and extension of the town, summer transport congestion, and improvement of coast waterfront facilities, this highlights a need to consolidate tourism as the engine of community economy.

Based on this, PRES (2010) draw three lines to drive reconstruction: 1) Improving connectivity in local and regional scale to improve tourism accessibility. 2) Rehabilitation of urban infrastructure mainly coastal waterfront facilities 3) Natural risk mitigation plan based on last tsunami event.

Although Tsunami mitigation is defined as a priority, its integration into the plan is based on economical and social development minimum disruption, therefore measures adopted are based on risk reduction rather than risk avoidance and they´re linked to previous approved projects or they discourage development in risk areas through land use regulation. This may be based in two facts; first, most damage area correspond mostly to holiday houses, and the size of the population doesn´t support investment for major measures, and also Pelluhue hadn´t registered previous tsunamis (PRC 2007). Nevertheless, measures adopted by the plan in different levels may have further impact in urban development.

7 c. 3 - Tsunami Mitigation Plan Tsunami risk studies (IEUT 2010) based on past tsunami event defined for Pelluhue a line at 11 m high as a safe Zone. According to this height, 30,55% of urban area (IEUT 2010) would be under restrict Zone. MINVU (2010) designates this area as a Zone 2 where development is not forbidden but is subject to mitigation actions.

35 Tsunami risk study. source: IEUT 2010

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Mitigation proposal beside of defining evacuation and preparedness plan as it´s required by central government (MINVU 2010) draws two lines of actions: 1-

Dune park and mitigation infrastructure to act as buffer zone in coast and river waterfront (Fig. 26). This measure is linked with previous community projects with investment previously approved, meant to improve waterfront public space to enhance Pelluhue´s touristic character. Based on current PRC (2007) information some previous projects linked to this measure are:

The estimated cost of mitigation infrastructure proposed by PRES is U$1.789.000 amount within previous projects founding. This would enhance social and economical feasibility of mitigation actions.

2-

Second measure for areas under 11 m high is discouraging development and restrict density through land use regulation, applying tsunami building codes (Fig 36).

36 Pelluhue, Tsunami Risk Mitigation Plan. Adapted from PRES 2010.

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In order to review a different approach of what it has been done in Constitucion, this research will analyze this second measure to evaluate the effects of density restriction in Pelluhue urban development.

7 c. 3 iii - Discouraging development & Restrict density Where development cannot be prevented, land use intensity, building value and occupancy should be kept to a minimum (NTHMP 2001). This can be achieve through land use regulation, transferring density to safer areas, restricting infrastructure and facilities in areas at risk such as sewer, water lines, roads and other public facilities, this can shape market forces to discourage development in less hazardous areas (NTHMP, 2001) and also can be achieve through economical or insurance incentives.

PRES (2010) for areas under 11m high proposes discouraging development and apply building codes through: 

Larger-lot zoning reducing plot ratio. Due to most damage area has already been developed PRES (2010) recommends economical incentives to encourage‖ fusion of lots‖.



Limiting the expansion of infrastructure in hazard areas (roads, utilities, sewer system).



Related to building codes, on the contrary of what has been recommend (NTHMP 2001, FAO 2008), PRES (2010) proposes typologies of continue facades which showed on last tsunami event that blocked and decreased wave velocity protecting houses behind.

Although Pelluhue is a rural beach resort with still low density of 21p/km2 and 46p/km2 in summer (PRC 2007) due to rapid growth experienced last 20 years and according to PRC 2007 growth projection in 30 years time, restricting density in damage areas in spite of its mitigate capacity will have effects in Pelluhue´s urban development and quality.

Impact of density restriction in urban quality

Vitality: restricting density in tsunami risk areas, according to risk studies (IEUT PUC 2010) would also addresses river flooding risk and spring tide (fig 35). Its main objective is reducing population exposed to risk without prohibiting development entirely. According to NTHMP (2001) and NOAA (2010) this, would reduce the need for shoreline mitigation structures that may help maintain natural shoreline dynamics in environmentally sensitive areas. Also, smaller buildings if destroyed would not result in as significant loss.

Main drawbacks are that it may be difficult to apply in dense areas already developed as the affected areas in Pelluhue. Politically may be difficult to achieve since municipalities rely on property tax revenues from waterfront developments NOAA (2010), and still when density is reduced part of the population will be exposed to risk, therefore would be essential keeping the community and owners informed about restrictions and risk they face, and would be mandatory developing an efficient warning and evacuation system.

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Fit: As it has been previously explained, based on current PRC (2007) information, Pelluhue has experienced a fast demographic growth increasing 27% its population in last census period (1992-2002) rising to 2298 permanent residents with a floating population of 6176 people. This growth and a geographic limit has lead to a linear development along coastal highway using low-lying areas next to Curanilahue river under tsunami and river flooding risk, developing the highest density of the settlement. On another hand, PRC 2007´s growth projection in 30 years time would expect a total population of 21.248 people and a need of 6067 houses. To addresses this growth PRC (2007) redefined zones increasing the density of this area up to160p/ha, with the smallest lots of 250m2 (fig 27). Although, PRC (2007)´s current land zoning would allow a capacity of 37.796 people within the urban limit (fig 28),

PRES (2010)´s recommendation of restrict density in areas under 11m

high will constrain development previously planned and will force transferring density to safer places.

37 PRC 2007 Zoning & Density. Adapted from PRC 2007

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38 PRC 2007, zoning and population capacity. Adapted from PRC 2007 This can be transfer to central area, using Constitucion similar models of ―fusion of Lots‖ to increase density or to upper hill areas designated with the same density. If urban center is densified, may be an opportunity to consolidate the area for permanent residents housing, differentiating intensity of uses between winter and summer, one of the PRES (2010) main objectives (fig 39). This measure can be hard to implement due to the area is already developed and density restriction will decrease land value. On this matter evaluate the option of avoiding total development may bring at long term higher contributions, may enhance natural landscape of river waterfront as touristic asset and may transparent the value of land affected.

39Transferring density to central area & Mobility Proposed. Adapted From PRES 2010

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Sense: According to PRC (2007) and to Council (2010) sources Pelluhue´s character is based in two main features; It´s a rural resort with strong prescience of natural landscape such as the beach, Curanilahue river and coastal mountain and Its built configuration is based on a foundational center of five blocks long with some heritage building from SXIX of one to two stories high with continues facades. The affected area is a contemporary urbanization of holiday houses developed after 1969 when coastal highway was built; it had an irregular physical configuration, with houses of one to two stories high that didn´t follow line and height (fig 40).

40 Pelluhue built Character before 27/F 2010. Source: PRC 2007 & PRES 2010 PRES (2010) proposal, although attempt to restrict density, also recommends continues facades configuration based on its performance mitigating wave force of last tsunami event. This configuration can enhance the access to the town, can consolidate the area that face the beach waterfront and can support the proposed mobility system that would differentiate seasonal movement, summer movement along waterfront and winter movement concentrated in town center (fig 41).

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41 Continues Facades for Tsunami risk areas. Adapted from PRES 2010 Control: To carry out these measures, PRES is studying incentives for voluntary relocation to safer areas.

According to NOAA (National Oceanic and Atmospheric Administration U.S. 2010), some instruments developed by Coastal management areas in U.S. can be reference restricting development in hazard areas: -

Transfer of development rights (TDR): is a voluntary, market-based program that enables hazard areas properties to purchase development rights in areas out of risk. To carry out this program is essential; keeping informed the future owners about restrictions and rights. New PRC has to ensure appropriate facilities for new density sites and would need uniform standards to define development right; density, area, floor-area-ratio, and height. This tool can help to stand the decreasing value of affected land.

-

Bonus Density: encourage development in safer areas through economic incentives or increasing density allowed in new sites.

Interim Conclusion Dealing with density and development in risk areas is the hardest task for planning. Although avoidance development is highly recommend (NTHMP 2001, FAO 2008, UNESCO, 2008), also politically and socially it‘s hard to achieve. Based on this, discouraging density is used as an option to stop development in areas at risk without forbidding it completely.

Restricting density in itself doesn‘t directly contribute to urban development, but encouraging and transferring density to safer areas is an opportunity to cluster development in safer environments and also intensifies and consolidates in this case town center functions.

Beside transferring density to safer areas, new PRC should also evaluate avoidance of development at risk areas that in long term can bring further contributions to Pelluhue, enhancing natural touristic assets, providing safer environments and may transparent as well the value of affected land.

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7 d. DISCUSSION As it has been previously discussed planning to mitigate tsunami forces is a complex task. Mitigation measures as it´s been recommend (NTHMP 2001, FAO, 2006, UNESCO 2008) such as avoiding or restrict density of development in hazard areas, adopting building codes or developing evacuation system, in most cases has high physical impact for the affected community, therefore, tsunami hazard is one among many aspects to be considered to guide a community physical development (Norigean Geothecnical Institute 2006).

Chilean government after last 27 F 2010, dealing with the aim of building back better focusing on community safety, has taken the opportunity of integrating tsunami risk into the concept of ―high risk area‖ in the article 2.1.17 of O.G.U.C defining new zones into the planning instruments that would restrict residential and critical facilities in hazard areas or would allow development subjected to mitigation action (MINVU 2010).

The analysis of Constitucion and Pelluhue show how mitigation measures when affect developed areas have significant effects in the structure of the whole city and in spite of their mitigate capacity; they may impact uses, architecture and character of the community, playing a significant role on urban development and sustainability of a settlement.

Main measure adopted in Constitucion of avoiding development and designating most damage area as greenbelt, would have significant urban implications. In terms of vitality, although its mitigate capacity is hard to prove, the greenbelt´s main contribution would be keeping away the most exposed population from risk as it has been broadly recommend (NTHMP 2001, FAO, 2006, UNESCO 2008). Other contribution of this measure in urban quality is recovering public access to Maule River as it´s been recommended (FAO 1992) and as it has been recognized by the community as a main natural asset that enhances and consolidates touristic sense and character of Constitucion, promoting economic diversification essential for sustainable redevelopment in a recovery process.

A key issue for its implementation is certain degree of feasibility. On this matter, although the main constrain of this measure is enforcing the expropriation of 159 properties, the low density of the area involved, would make it economically and socially possible. Also linking this measure with previous community needs, mainly controlling river flooding risk would greatly enhance the political importance and feasibility of disaster reduction programs (Berke and Beatley, 1997). Its implementation also would rely on an integrated management and control which finds an opportunity in the reconstruction process to promote multidisciplinary and inter-sectoral approaches to coastal zone management (FAO, 2006), integrating actors, investment, planning instruments and responsibilities under common goals, contributing to the feasibility of the greenbelt.

Although the greenbelt has been a polemic decision due to involves the expropriation of 159 properties with a high social and economic initial cost, at long term it may bring higher contributions, not just in providing a safer environment but also enhancing the development and urban quality of the whole settlement, supporting objectives and projects that address previous community needs and enhance the river as main touristic asset.

Application of building codes on another hand, following requirements of the norm NTM 007 2010, may have contradictory effects for urban quality.

Regarding vitality, building codes would protect structures from

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collapse, but they don´t directly would save lives, therefore is essential to aware the population of the risk they are exposed, developing efficient early warning system and clear evacuation plans.

Also, building codes requirements of elevating residential spaces and keeping distance between buildings, may impact on the one side ground floor activities forcing alternative uses without enough demand to support them and on the other may impact physical configuration of the urban center; disrupting the sense or character of blocks continuity and affecting also heritage buildings that give identity to the community.

An option of applying building codes with a sense of continuity would be integrating them in housing densification proposed by PRES (2010) and MINVU (2011). Although this may solve previous problems of housing demand keeping local character of block typology, it may present main contradictions with what it´s been recommended of avoiding or restrict density in tsunami risk areas (NTHMP 2001, FAO, 2006, UNESCO 2008). This may raise a further discussion about to what extent low frequency of the event may allow development adopting higher mitigation standards.

In spite of its mitigate capacity, building codes may constrain important aspects of urban development regarding cost of construction, restriction on uses and urban character. Therefore, for its implementation is essential to adapt them to local reality, providing economic feasibility, design guidelines, efficient management and certain degree of flexibility regarding uses and character.

On this matter the study of Pelluhue, shows that a smaller settlement that hadn´t registered

previous

tsunamis, presents a higher need to adapt mitigation measures to local reality in order to minimize economic and social disruption. Based on this, a main measure adopted by the plan is discouraging development at hazard areas restricting its density through land use regulation.

As it has been shown in both cases, dealing with density and development in high risk areas is the hardest task for planning. Although avoiding development is the most recommended (NTHMP 2001, FAO 2008, UNESCO, 2008), also politically and socially it‘s hard to achieve. Therefore, discouraging density is used as an option to stop development without forbidding it completely. Although in short term this may be a more feasible solution, main drawbacks are that part of the population is still exposed to risk and on another hand the value of affected land may highly decreased affecting social and economical sustainability.

Regarding its urban effects, restricting density in itself doesn‘t directly contribute to urban quality, but encouraging and transferring density to safer areas is an opportunity to cluster development in safer environments and also intensifies and consolidates town center functions. However, the plan for Pelluhue should also evaluate avoidance of development at risk areas, that as it has been shown, in long term may bring further contributions to urban quality, enhancing river surroundings as natural touristic assets, providing safer environments and it may transparent as well the value of affected land supporting the three aspects of sustainable development.

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8. CONCLUSIONS Literature review and cases studies analysis have shown that due to its nature of low frequency but high consequences, dealing with tsunami mitigation means making trade off among competing goals. The recovery context presents opportunities to enact policies to mitigate future disasters as it has been demonstrated in Chilean context, which incorporated tsunami to the concept of ―high risk area‖ restricting development in most damage areas hit by the tsunami. This has lead to major changes in land use such as the designation in Constitucion of a greenbelt as buffer zone, the restriction of density in Pelluhue and definition of building codes, that beside their mitigate capacity, in different levels may have significant impact in the quality of urban development.

To answer the research question, assessing if this impact can contribute to the urban quality of coastal settlements? The methodology proposed addresses five aspects of urban development that allow evaluating broader effects of mitigation in the urban quality of coastal settlements close related to urban sustainability.

In terms of vitality or the capacity of providing a safer environment, it´s been shown that no mitigation measures, beside avoidance development at high risk areas, can provide complete protection of tsunami events. Based on this, the main role of the greenbelt in Constitucion would be keeping away the most exposed population from hazard, while building codes role is mainly protect property from collapse, but they don´t directly protect lives. In Pelluhue as well, although restricting density attempts to reduce population exposed to risk, when development is allowed it may even confront a greater risk, therefore is essential and mandatory an advance warning systems, efficient evacuation plans and keeping informed the community of the risk they are exposed.

In terms of Sense or character, the contribution of mitigation is debatable. While the greenbelt may recover the relationship of the city with the river as an historical touristic asset, building codes may have ambiguous implications in the character of the built form, uses of ground floor and heritage buildings of the city centre. This will need special consideration provided by new PRC regarding design guidelines, uses and heritage assets protection. PRES Pelluhue on another hand suggests keeping continued facades in damaged areas due to its performance resisting last tsunami impact. This is an example of how building codes should be evaluated to be adapted to the needs and reality of each locality.

In term of Access this research has shown that mitigation measures regarding avoidance of development may become one of the main contributions to urban quality. The designation of high risk area in Constitucion, as buffer zone for public space uses, not just would recover the public access to Maule River, but also would support previous community needs and would enhanced touristic character of the city, able to promote and diversify economic local activities, essential issue to achieve sustainable redevelopment.

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In terms of fit or linking mitigation actions with broader community needs as it´s been recommended (Berke and Beatley, 1997), it would enhanced the political importance and feasibility of mitigation measures essential for long term sustainability of a mitigation plans. This has been presented in both case studies; in Constitucion, linking the greenbelt with previous projects for flood control, not just enhance its feasibility but also its social acceptance and in Pelluhue, mitigation linked to waterfront improvements with previous funding approved makes it economically possible.

On another hand restricting density in Pelluhue hazard areas presents one of the main constrains to address growth projections planed by current PRC (2007). This, as it has been present in both cases, show that dealing with density and development in high risk areas is one of the hardest tasks for planning. On this matter, although avoiding development presents an initial social and economic cost due to enforcing expropriation at long term may bring higher urban contributions. Discouraging density on another hand although in short term may be a more feasible solution, still will keep part of the population exposed to risk and the value of the affected land may highly decrease. Even though restricting density in itself doesn‘t directly contribute to urban quality, encouraging and transferring density to safer areas is an opportunity to cluster development in safer environments and also it intensifies and consolidates town center functions.

As it´s been previously discussed, a key issue to integrate tsunami mitigation is based on, certain degree of feasibility, Control, implementation and management, where the reconstruction process has presented opportunities to integrate actors, investment and planning instruments under common goals. A main point for its feasibility as it´s been further discussed (see NTHMP 2001, Geis 1996, Petterson, J. 1999), it´s linking this measure with other more frequent occurring hazards that not just enhance its political importance, but mostly strengthen its social acceptance supporting like this the economic, social and environmental aspects of development.

Finally, taking in consideration the overall implications of mitigation measures in the urban development of both case studies; mitigation based on risk reduction such as restricting density that lead responsibility to each owner of the risk and cost they are willing to take, although in short term may be a more feasible solution, at long term may have some adverse results; the exposed population may confront greater risk, and the cost of the decreasing land value would be assumed by each owner, this would confront social and economic sustainability of development. Building codes on its side may also present some contradictions mainly regarding urban character, uses and activities that will need special considerations by new PRC to provide guidelines and flexibility to adapt to local reality. On another hand, major measures regarding risk avoidance in hazard areas such as the designation of a greenbelt in Constitucion, in spite of its initial high social and economic cost of enforcing the expropriation of land, at long term may provide higher contributions to a broader community, It would also support previous community needs, would enhanced main city natural character, and most important, it would keep most exposed population out of risk, supporting issues of social, economic and environmental sustainability and contributing to further aspects of urban quality improvement.

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9. RECOMEDATIONS 1-

General recommendations to integrate tsunami mitigation achieving sustainability and urban quality improvement: a.

For local Planning is essential a multi-hazard community risk assessment maps of global physical processes and local resources and buildings and historical data of past and current disasters (Mileti 1999). This information must be spread toward the community to evaluate and decide best mitigation actions that community can take.

b.

To achieve sustainability, mitigation will require a long term view that takes into account the overall effect of mitigation efforts on this and future generations. (Mileti 1999) on this matter is essential understanding the opportunity that the recovery process presents to encourage land use management techniques to reduce exposure to hazards as the most long term and sustainable hazard mitigation techniques.

c.

To enhance the feasibility of mitigation it must become itself a basic social value, this will enhance social acceptance of mitigation actions. On this matter, several researches have shown that recovery is most effective when community-based organizations assume principal responsibility. It is essential to see mitigation as a process that entails decision making and interaction among all stakeholders; households, businesses and the community at large (Mileti 1999). Also will be essential spread information toward the community about the risk, mitigate capacity and other contributions of mitigation actions.

2-

Recommendations for greenbelt feasibility: a.

To maintain the mitigate capacity of the greenbelt as a buffer zone, is essential to ensure proper planning and management of vegetation to ensure a proper design and the right maintainace of the planned forest features .

b.

To bear the social cost of restricting development on high risk area is essential a closer collaboration between the hazard communities achieved by spreading information of mitigation objectives, contributions and constrains.

c.

To bear economic cost of greenbelt implementation, as it has been developed at Hilo´s, general government can develop a land bank as a fund for acquisition of land in hazard areas to allow the preservation of open space.

3-

Recommendations for building codes feasibility: a.

To bear the cost of structure improvement it would be essential providing to the community economic incentives. Such as reducing property taxes, waiving of permit and inspection fees, and low interest loans (NTHMP 2001). The most frequently suggested financial incentives are insurance premium reductions resulting from the implementation of mitigation programs.

b.

Evaluation of each community local reality and needs would be essential to ensure that effective mitigation techniques can be applied without disrupting the original characteristics of each settlement. On this matter flexibility may be needed to adapt building codes to local reality.

c.

Although mitigation measures can reduce tsunami damage, especially in the statistically morefrequent small tsunamis, they will not ensure to withstand the intense forces associated with larger events (NTHMP 2001). Therefore when development cannot be avoid is essential

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enlighten individual property owners about the risk they face (Mileti 1999). On this matter insurance incentives could be an alternative tool to engage individual property owners on risk reduction programs. d.

To keep urban character of each settlement will be necessary for new PRC to provide guidelines of urban and architectural design following specific height and lines to apply urban mitigation techniques, keeping a coherent urban configuration able to enrich existing urban patterns.

4-

Recommendations for density restrictions feasibility: a.

Although restricting density attempts to reduce population exposed to risk, when development is allowed will be essential keeping informed new owners and the entire community of the risk they are exposed, their restrictions and rights and the mitigation tools they can take. Also should be mandatory providing and efficient early warning system and a clear evacuation plan.

b.

Safer areas (town center and other medium density areas) should be provided with proper public facilities and infrastructure to receive and encourage additional density transferred from risk areas.

c.

Tools such as transfer of development right (TDR) should be clearly developed not just to encourage transferring density but to stand the decreasing value of land. New PRC has to ensure appropriate facilities for new density sites and would need uniform standards to define development right; density, area, floor-area-ratio, and height. This tool can help to stand the decreasing value of affected land.

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