Expert Sound Alarm: Tokyo at Risk of Devastation from Imminent Earthquake Directly Beneath the Tokyo Metropolitan Area

Disturbing tremors have been occurring frequently.

During the week of March 2-9, there were 79 earthquakes of intensity 1 or higher in various parts of Japan. The most active area is Chiba Prefecture, where more than 40 tremors of intensity 1 or higher have occurred since late February, with epicenters in the southern and eastern offshore areas. Yoshinobu Tsuji, a former associate professor at the Earthquake Research Institute of the University of Tokyo and a visiting researcher at the Fukada Geological Research Institute. 

The fact that there have been so many earthquakes in a row suggests that something big is going on underground. This is a different situation from before. It could be a sign of a huge earthquake.

Slow slip, in which plates and faults slide slowly, is thought to be the cause of the Chiba earthquake. What is frightening is that the current situation is very similar to the situation just before a huge earthquake occurred in the past. Even before the Great East Japan Earthquake in March 2011 and the Noto Peninsula Earthquake in January this year, slow-slip earthquakes had occurred frequently. Robert Geller, a professor emeritus at the University of Tokyo and a seismologist, points this out.

The mechanism of earthquake occurrence is complex and cannot be predicted by current science. A major earthquake could occur anywhere at any time. However, statistics have shown that the probability of a major earthquake occurring in the vicinity of a seismic swarm is somewhat higher.

According to the GSI, the slow slip in Chiba caused the plate boundary to move southeastward by 2 cm. The greatest concern is an earthquake directly under the Tokyo metropolitan area.

If the epicenter moves further southeast, be careful. It will stimulate the triple junction of the Sagami Trough, the Japan Trench, and the Izu-Ogasawara Trench, which can cause an earthquake directly under the capital.

An earthquake directly under the Tokyo metropolitan area would destroy Tokyo. A massive tremor with an intensity of up to 7 on the Japanese seven-stage seismic scale would hit the central part of the city. Takao Sakaguchi, director and special researcher at the Citizen’s Research Institute for Disaster Prevention, sounds the alarm.

The Cabinet Office estimates that up to 610,000 buildings will be completely destroyed or destroyed by fire, and 23,000 people will die, but it is questionable whether that will be the case.The Noto Peninsula earthquake also caused more damage than expected.

What is frightening is the possibility of large-scale urban fires caused by electrical appliances and gas stoves. Not only the downtown area, with its many wooden houses, but also the Yamanote area, cannot be regarded with optimism. Mr. Sakaguchi continues.

The Tokyo Metropolitan Government has designated 52 areas within the 23 wards as densely wood-framed buildings, but they are also scattered within Ota and Shinagawa wards inside the 7th Ring Road. Narrow roads where fire engines cannot easily enter. There is a risk that the fire will spread further. Tower apartments that are thought to be earthquake resistant also need to be careful. The higher the floors are, the more violent the shaking will be, and the more furniture will tip over and fall.

The government estimates that a tsunami of up to 3 meters in height will occur, submerging underground malls and subways in the city. It is said that a vast area of the metropolitan area will be flooded. The eerie footsteps of a gigantic earthquake that will cause severe damage is definitely approaching.

From the March 29, 2024 issue of FRIDAY