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DISASTER MANAGEMENT
Smart Solutions for
disaster management
Learning from the Great East Japan Tsunami and the Accident at Fukushima NPS
Figure 1: Crustal Movement
Figure 2: GPS Stations of GSI
Shunji Murai
Professor Emeritus,
University of Tokyo, Japan
During and after the Great East Japan
Earthquake and Tsunami, about
20,000 persons died or are still missing,
of which 92.5% were victims of the
Tsunami. The fourth biggest earthquake
plus Tsunami in history swept away
220,000 houses and 18,000 fi shing
boats. The control points installed at the
sea bottom 130 km offshore near the
epicenter showed 24 m horizontal crustal
movement to east-east-south and 5 m uplift
vertically, while a GPS Station at Ojika,
which is located on the coast nearest to
the epicenter showed 5.3 m horizontal
movement in the same direction and 1.2
m settlement vertically which would be a
trigger to generate Tsunami (see Figure 1).
Prediction of earthquakes
Using GPS data provided by Geospatial
Information Authority (GSI), Japanese
Government, the author’s group succeeded
Figure 3: Pre-signals of
earthquake with GPS Data
Figure 4: Location of GPS stations of interest
to predict earthquakes through the trend
analysis of time sequential data. There
are about 1,200 GPS Fixed Stations
called electronic control points all over
Japan as shown in Figure 2. The data
derived from these GPS stations can be
downloaded free of charge on the Internet.
Figure 3 shows an example of predictions
in the case of Great East Japan Earthquake
including the critical pre-signals of 5
weeks, 4 weeks and 3 weeks respectively
before the earthquake. A symbol x
shows the epicenter. The most critical
pre-signals were 3 weeks before the
earthquake though the signals weakened
afterwards until the earthquake occurred.
This behavior of the early signals is
interesting but the reasons are still
unknown. We observed the possible
occurrence of an earthquake before the
event but we did not alert the public as
we had no authority to do so. But now
we are permitted to develop a business
that will provide a service on earthquake
prediction as a commercial activity.
Japan is surrounded by four tectonic
plates including the Pacifi c, Philippines,
Eurasian and North American Plates (see
Figure 4). Mt. Fiji stands at the junction of
Philippines, Eurasian and North American
Plates. In the past Mt. Fuji’s eruptions
were linked to the giant earthquakes.
Therefore Japanese are concern about
the possibility of the next eruption of
Mt. Fuji in near future. We have only
one GPS station on the Pacifi c Plate,
which is at Minami Torishima, which did
not move much during the Great East
Earthquake. Ojika GPS Station nearest
to the epicenter showed pre-signals 15
days and 3 days before the earthquake as
shown in Figure 5 though the GPS station
ceased its operation after the earthquake.
Coordinates January 2013 | 35