On November 20, 2021, the Metropolitan Police Department announced that it will implement traffic restrictions, including the Metropolitan Expressway, in order to carry out large-scale training assuming an earthquake directly beneath the Tokyo metropolitan area on the 21st (tomorrow). Since traffic congestion is expected, we are calling for the use of detours.
(For 15 minutes from 9 am, the inflow of vehicles toward the city center is prohibited at 42 major intersections of Ring No. 7. At the same time, highways such as National Highway 4, National Highway 20, and National Highway 246. Traffic is also restricted at 61 major intersections in Tokyo. On the Kannana-Dori Yokohane Line and Haneda Line, the traffic is closed for 30 minutes from 9 am, about 7 km from Daishi Junction to Heiwajima Parking Area, and Daishi, Haneda, and the airport. Close each entrance to the west and Heiwajima.)
Regardless of the scale, the traffic regulation of 15 to 30 minutes seems to be a modest training that minimizes the impact on the lives of the residents.
What is an earthquake directly beneath the capital?
According to Kotobank
An earthquake directly beneath the Tokyo metropolitan area is a major earthquake of magnitude 7 class that may cause the greatest damage to the metropolitan area around Tokyo. Since the metropolitan area centered on Tokyo is a region where central functions such as national politics, administration, finance, and economy are concentrated, once a large earthquake causes great damage and the central functions are impaired, the impact will be domestic. Not only that, there is concern that it will spread widely overseas.
Past damage
Earthquakes directly under the Tokyo metropolitan area occur in a cycle of 200 to 300 years, and the Great Kanto Earthquake of 1923 has caused an estimated 105,000 deaths and missing persons, and it is estimated that approximately 1.9 million people have been affected (most of the victims). Is Tokyo and Kanagawa Prefecture). In addition, about 109,000 buildings were completely destroyed and about 212,000 were completely destroyed. It is reported that the fire damage in Tokyo is the center, but the center of the damage is in Kanagawa prefecture where the epicenter fault is located, in addition to the collapse of the building due to vibration, the land subsidence and landslide due to liquefaction, and the damage caused by the tsunami in the coastal area .. The headline of the Tokyo Daily Newspaper is "Turn into the sea of fire in the whole city of Tokyo" "Nihonbashi, Kyobashi, Shimotani, Asakusa, Honjo, Fukagawa, Kanda almost annihilated and injured 100,000" "Telephone, telephone, train, gas, Yamanote" All the lines are cut off, "Yokohama City is annihilated, tens of thousands of deaths and injuries", "Evacuated people are approaching starvation", "A lot of dead bodies in the direction of Koto", "Fukagawa survivors in the fire are starving", "Yokohama ash becomes Tokyo" The heading was seen.
Forecast of earthquake directly under the capital
It is predicted that 70% of earthquakes directly under the capital will occur in the next 30 years. In the worst case, it is estimated that 23,000 people will be killed, 610,000 houses will be destroyed and burned down, and the economic damage will reach 95 trillion yen, and there is no doubt that it will cause large-scale damage to Japan. The evidence of the occurrence in 70% is based on the following eight earthquakes. (Announced by the Cabinet Office)
① August 23, 1782 "Tenmei Odawara Earthquake" (M7.0)
(2) March 11, 1853 "Kaei Odawara Earthquake" (M6.7)
③ November 11, 1855 "Ansei Edo Earthquake" (M6.9)
④ June 20, 1894 "Meiji Tokyo Earthquake" (M7.0)
⑤October 7, 1894 "Earthquake near Tokyo Bay" (M6.7)
⑥ January 18, 1895 "Earthquake in the southern part of Ibaraki Prefecture" (M7.2)
⑦ December 8, 1921 "Earthquake in the southern part of Ibaraki Prefecture" (M7.0)
⑧ April 26, 1922 "Earthquake near Uraga Suido" (M6.8)
These major earthquakes occurred between the 1703 "Genroku Kanto Earthquake" (M8.2) and the 1923 "Taisho Kanto Earthquake (= Taisho Great Kanto Earthquake)" (M7.9).
The Earthquake Research Committee predicts the probability of a major earthquake of magnitude 7 class in the future, with 220 years from the "Genroku Kanto Earthquake" to the "Great Kanto Earthquake" as one cycle. Since it has occurred 8 times in 220 years, it is calculated once every 27.5 years. Based on this, when applied to the formula for future prediction used in seismology, the probability of occurrence of "70% within the next 30 years" is derived.
Damage estimate
The damage caused by the earthquake is the collapse of buildings, fires, land subsidence due to liquefaction, landslides, and tsunamis.
Japanese buildings have been designed and strengthened according to the new earthquake resistance standards reviewed in 2000 so that they will not collapse or collapse even in the event of a major earthquake that may occur during the remaining period of the building. It is said that 100,000 houses collapsed in the past Great Kanto Earthquake, but it seems that many buildings will not collapse. Damage to fire is also limited. Most of the current buildings are made of reinforced concrete, and the spread of IH products has reduced the number of households that use fire directly as they did 100 years ago. On the other hand, the buildings in Tokyo are more dense than in the past, and there are some areas where the distance between buildings is only a few meters as it gets closer to the city center. From this point of view, the possibility that the fire will spread quickly and on a large scale will be sufficient.
Liquefaction in Tokyo can cause great damage. In particular, lowlands such as Koto Ward, Sumida Ward, Katsushika Ward, Arakawa Ward, Ota Ward, and Edogawa Ward have many areas below sea level. In addition to the collapse of buildings, many of the elevated roads and roads collapse, cutting the roads and making it difficult to move by car.
From the underground point of view, Tokyo has an underground shopping mall connected to subways and buildings. In recent years, about 3,000 collapse accidents occur annually. Most of the underground facilities in Tokyo were built between 1950 and 1970 before and after the 1964 Tokyo Olympics, and they are aging and have not undergone drastic maintenance.
Tokyo has few mountains, but the border between the western part and Kanagawa prefecture is partially mountainous. In the western part of Kanagawa prefecture, mountainous areas such as Odawara and Hakone are widespread, and there are many buildings along the mountains. Since the Great Kanto Earthquake of 1923, there have been no major earthquakes in this area, and the ground on the slopes has been weakened by forest development, so many buildings were involved in unexpected landslides and human damage was caused. Will occur.
Depending on the magnitude of the earthquake, a tsunami may occur in the coastal area of Kanagawa Prefecture. It is difficult to imagine large-scale damage such as the Great East Japan Earthquake, but if a large tsunami occurs, it will cause some damage in the coastal areas.
By the way, according to the damage estimation of the past earthquakes directly under the capital, it is estimated that if an earthquake occurs in winter or evening, about 50% will die due to fire, about 30% will die due to collapse of buildings, etc., and about 10% will die due to landslides. ing. Damage estimation of the earthquake directly under the capital (overview) (bousai.go.jp)
Response of the Self-Defense Forces
For example, suppose that an earthquake directly beneath the capital occurred on a weekday evening in January. Many buildings collapsed and a fire broke out in the area. Major roads, including elevated roads, will collapse and be cut off, and about 10 million citizens of Tokyo and the prefecture will evacuate in a chaotic manner while searching for safe areas. Electricity, water and gas will be cut off, and it will be difficult to refuel gasoline. It is difficult to survive outdoors in the city center in winter. Detention facilities and supplies for the victims are needed.
The Ground Self-Defense Force (150,000) is the main force in disaster relief dispatch. As was the case with the 2011 Great East Japan Earthquake, a total of 100,000 troops from Hokkaido in the north and Kyushu in the west will gather toward Tokyo. The number of vehicles will also exceed 10,000. If the disaster area is Tokyo / Kanagawa prefecture, the requirements for road enlightenment, life search / rescue, and protection of disaster victims cannot be compared. The unit will be active in months or years.
First, the first barrier is grasping the situation. It becomes more difficult to understand which area is damaged and how much damage is being done, and the situation of the victims is large. In particular, fires occur at different times, and the damage situation changes fluidly because there is no means to extinguish the fire. Appropriate understanding of the situation and distribution of limited force will determine the success or failure of the initial lifesaving.
Once you have an overview of the situation, move your troops and occupy the base.
The closer to the epicenter, the more likely it is that the road will be disrupted due to landslides and that it will collapse due to liquefaction. In this case, you will have to look for a detour or improve the road as an emergency. Since many SDF vehicles are wide and have a large turning radius, the presence or absence of a large road has a great effect on the maneuverability of the unit.
When you arrive at the scene, you will cooperate and cooperate with the person in charge of the city / prefecture, police, and fire department to carry out various activities. Obviously, the on-site information is the most accurate and reliable. Based on prior information, detailed on-site reconnaissance will be conducted, priorities and procedures will be determined, and the unit will carry out the work.
At the beginning of a disaster, lifesaving is the highest priority. It is often said that "the survival line is within 72 hours", but the time is further restricted if information gathering and the maneuvering of the troops are included. For this reason, the unit involved in the initial work conducts search activities with a minimum of pauses from morning till night. Machines such as dozers and excavators cannot be relied on to save lives. This is because there is a danger of killing the rescuer. Inevitably, the work will pursue manual work. It is unknown when a building that has collapsed due to an aftershock will collapse again. Basically, all search work is life-threatening, and the situation continues to be nerve-wracking with fear, a sense of mission, and fatigue.
Detention facilities for disaster victims will also be an issue. No matter how much Tokyo is, if the disaster occurs during a time when people are concentrated in the city center, the capacity of safe areas such as gymnasiums and schools will be limited. It is also necessary to replenish supplies for living there for several months. After the disaster, everything will be in short supply for several weeks. The Self-Defense Forces have some supply capacity, but they are self-sufficient. It is Sekiyama that supplies 150,000 people by logistical units and hundreds of thousands of people including other units. It seems that there will be support from local governments and volunteers from all over the country, but considering that the transportation of goods will be restricted due to road disruptions, it will be very difficult to continue the care of millions of people. ..
Summary
The earthquake directly beneath the capital is an unprecedented disaster, similar to the Great East Japan Earthquake. The difference between the two is probably the density and number of the affected population and the damage caused by the fire. At the beginning, I touched on police training, but the current situation is that only the minimum can be set. Lifesaving and support by the Self-Defense Forces, police, and fire departments are limited by the number of organizations. Especially in the case of an earthquake disaster in a densely populated area such as the Tokyo area, it is important not to rely on rescue but to develop infrastructure such as buildings and roads that will not collapse even in a big earthquake.
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