Recent Successes in Earthquake Predictions in Japan
A Author:
Shunji Murai, Ph.D.
Professor Emeritus, University of Tokyo Advisor, Japan Earthquake Science Exploration Agency (JESEA)
new approach for the earthquake prediction
Global Navigation Satellite System (GNSS) is a satellite
using daily data from the Global Navigation
system that is used to pinpoint the geographic location
Satellite System (GNSS) observed by 1,300 GNSS-
of a user's receiver anywhere in the world. Satellite-based
based control stations all over Japan is making waves and
navigation systems use a version of triangulation to locate
headlines. This approach was developed by a pioneering
the user, through calculations involving information from a
group of scientists who have been working on the method
number of satellites. Each satellite transmits coded signals
since 2002. Eight earthquakes occurred so far in 2014 with
at precise intervals. The receiver converts signal informa-
larger than Japan Meteorological Agency’s (JMA) seismic
tion into position, velocity, and time estimates. Using this
intensity scale 5 that were predicted successfully with the
information, any receiver on or near the earth's surface
newly developed prediction method. Japan Earthquake
can calculate the exact position of the transmitting sat-
Science Exploration Agency (JESEA) started its official
ellite and the distance (from the transmission time delay)
efforts in earthquake prediction in February 2013, attract-
between it and the receiver. Coordinating current signal
ing more than 30,000 individual members who regularly
data from four or more satellites enables the receiver to
receive weekly MEGA earthquake predictions. Due to the
determine its position.
success of JESEA’s predictions, several TV programs and magazines have reported the agency’s achievements since May 2013.
New Methods of Earthquake Prediction Though the methods were relatively simple with the analysis of the daily data (a week data) observed at 1,300 GNSS stations and released every Monday by the Geospatial Information Authority (GSI). JESEA developed and currently uses the following methods: • Weekly change: the change between the maximum and minimum height to be automatically checked to determine whether the change exceeds the threshold or not. • Two-year trend: the abnormal rising or sinking to be automatically checked. • Six-month accumulated deformation: accumulated value of rising or sinking to be automatically checked. The above indices will then be represented in graph or map with respect to the prefecture category or all Japan. After checking the graphs and maps, careful interpretation for the prediction is executed. Professional experience and knowledge would be necessary for the prediction. Every word in the prediction document should be based on scientific back data or graphic representation.
Achievement of Predictions Several cases of larger earthquakes occurred in 2014 are North Nagano Prefecture Earthquake
Sources: NBC News, The Guardian
introduced hereafter together with the warning used in the mail magazine served to the individual members.
Technology | February 2015
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