Projections on intensities and potential damages caused by earthquakes in Japan was released last week by a working group under the government’s Central Disaster Management Council. The group studied the effects of an earthquake directly under Tokyo and released maps with different epicenters in and around Tokyo.
The council is expected to come up with forecasts of casualties and structural damage for different possible earthquakes early in the new year.
The simulations were based on 18 possible epicenters. The greatest damage is expected from an earthquake having its epicenter in the northern part of Tokyo Bay.
Five of the epicenters were forecast as possible sites for earthquakes with a magnitude of 7 or greater on the Richter scale. The largest temblor with an expected magnitude of 7.5 is forecast to occur along the Kannawa/Kozu-Matsuda fault belt.
The working group also predicted tsunami would be generated by the earthquakes, with the largest ones within Tokyo Bay expected to measure less than 50 centimeters. Tsunami could reach as high as two meters along the Sagami Bay.
The most devastating earthquake could be one with an epicenter in the area where the Philippines Sea plate bumps into the North American plate in the northern part of Tokyo Bay between Tokyo and Chiba Prefecture.
That earthquake is expected to have a magnitude of 7.3 with an epicenter between 20 to 30 kilometers underground.
In the event of that earthquake, the eastern half of the 23 wards of Tokyo and Urayasu can be expected to record shakes of upper 6 on the Japanese intensity scale. Surrounding areas would record quakes of lower 6.
An earthquake with an epicenter in the eastern part of Tokyo is predicted to have a magnitude of 6.9. Almost the entire central Tokyo area would record shakes of lower 6, with the central part of the region recording quakes of upper 6.
Areas with even weaker underground foundations could be expected to record quakes with an intensity of 7.
It was a first attempt by the central government to map damage from possible earthquakes directly under Tokyo. The intensity forecasts were created for areas divided into 50-meter squares in central Tokyo.
In any event, plans have to be made soon to deal with what will obviously be a major disaster.
“Seismic activity is moving from a quiet period to a more active one,” said Megumi Mizoue, professor emeritus at the University of Tokyo and chairman of the Central Disaster Management Council’s working group.
