Theme C: The Restless Earth Revision Summary 1. Plate tectonics theory Learning Outcomes – by the end of this section, you should be able to • describe the structure of the Earth (core, mantle, crust); • know that the Earth’s crust is made up of a number of plates • understand how convection currents cause plate movement;
1.1 The structure of the earth Section Core
Characteristics (what it’s like)
Mantle Crust
1.2 How do convection currents move plates? How do convection currents actually move the plates? By three means: o ____________between the convection current and the bottom of the plate o as the colder, denser plate sinks (or_________) into the mantle, it pulls the rest of the plate along (______________________) o as new magma seeps up into the crust, it pushes the plates apart (_____________________)
1.3 Plate margins - processes Learning Outcomes – by the end of this section, you should be able to • show knowledge and understanding of the processes and landforms associated with following plate margins: (1) destructive plate margins and subduction zones & ocean trenches (2) collision zones and fold mountains (3) constructive plate margins and mid-ocean ridges (4) conservative plate margins and fault lines.
and landforms Direction of movement Constructive
Destructive
Landforms
Processes producing these landforms
Collision zone
Conservative
2. Tectonic activity in the British Isles Learning Outcomes – by the end of this section, you should be able to • show knowledge and understanding of the characteristics and formation of: lava plateau; basaltic columns; volcanic plug • the causes and impacts of the Dudley earthquake, 2002, an earthquake in the British Isles
2.1 Tectonic features in our own back yard Feature Lava Plateau
What it’s like
How it’s formed
Basaltic columns
Volcanic plug
2.2 Earthquakes in the British Isles
: Dudley Earthquake, 2002 How was it caused?
What were its impacts?
3. Earthquakes - can they be managed? Learning Outcomes – by the end of this section, you should be able to • understand the global distribution and causes of earthquakes in relation to plate boundaries; • know and understand that there may be physical consequences of earthquakes: – liquefaction; – tsunami; • know and understand the causes and impacts of earthquakes and evaluate the management responses using two case studies (one in an MEDC and one in an LEDC): – identify the plates involved; – describe the short and long term impacts on people and the environment; – evaluate the management response to earthquakes including o prediction/precautions before the event and o immediate and long term strategies implemented after the event.
3.1 Earthquakes - where and how? •
The definition of an earthquake is ___________________________________________________________ ______________________________________________________________________________________
•
How do earthquakes occur?
•
The focus is ____________________________________________________________________________ whereas the epicentre is __________________________________________________________________
•
Earthquakes are measured using ___________________ and their size is classified using the ___________ scale.
•
Most major earthquakes are found _______________________________________ plate margins.
3.2 The physical consequences of earthquakes Tsunamis are caused when the earthquake moves the plates and seabed __________________, lifting it several metres, sending the wave out from the epicentre.
Liquefaction occurs when the shaking causes the grains of soil to ____________________ with each other and instead become surrounded with water. This makes the ground act like a _______________ liquid, and buildings may collapse. After the shaking, the ground becomes _____________ again.
Their characteristics change as they enter shallow water:
In deep water… Wave length Wave height Speed
…at the shore
3.3 Earthquakes - causes, impacts & management response
Loma Prieta, 1989 The ________________ & ___________________ plates moved in different directions, but ________ at the plate margin build up of ____________, causing plates to slowly ___________. Then, in _________, all the pressure was suddenly released in a massive ____ earthquake whose epicentre was at ____________.
Causes
Last major earthquake prior to 1989 was in _____________ (measuring ____ ). Since then, the ________________ & ___________________ plates moved in different directions, but ________ at the plate margin build up of ____________, causing plates to slowly ___________. Then, in October 1989, all the pressure was suddenly released in a massive __.9 earthquake (epicentre at ____________).
Impacts
•
Short term
•
Short term
•
Long term
•
Long term
•
Predictions
•
Predictions
•
Precautions
•
Precautions
•
Response o Immediate
•
Response o Immediate
Management response
o
•
Long term
o
Long term
Differences in the impacts of earthquakes in MEDCs and LEDCs
Similar sized earthquakes cause less damage in MEDCs than LEDCs because LEDCs are ___________. This means they can spend less money on strategies to prepare for earthquakes, such as…
4. Rock Types Learning Outcomes – by the end of this section, you should be able to • understand the formation and basic characteristics of the following rock types: – igneous – basalt and granite – sedimentary – limestone and sandstone – metamorphic – marble and slate Key Terms
Rock type Igneous o Granite (Intrusive)
o
Basalt (Exstrusive)
Sedimentary o Sandstone
o
Limestone
Metamorphic
How it’s formed
Key Terms Definition questions are common in the exam. Typically, they are worth 2 marks, which means you’ve got to make two points in your answer. Use the following table to help you complete definitions with two points for each of the following key terms (one has been completed for you as an example): Key term
1st point
2nd point
Core
This is the central part of the earth.
It is divided into a solid inner core and liquid outer core.
Mantle
Crust
Convection current
Plate
Plate margin
Volcano
Volcanic plug
Lava plateau
Earthquake
Richter Scale
Seismograph
Epicentre
Focus
Liquefaction
Tsunami