Revision of emergency measures plan for Tokyo inland earthquake to cut deaths to less than half, focusing on fire control

A Tokyo Inland Earthquake, bringing violent shaking of magnitude 7 (M7) or higher, could strike the capital region. Such an earthquake is expected to occur in the next 30 years at a probability of about 70%. It could deeply affect economic and social activities across the country by hitting the metropolitan area where political, economic, and administrative functions are concentrated. At a cabinet meeting on June 12, the government decided on a major revision of the "Basic Plan for the Promotion of Tokyo Inland Earthquake Emergency Measures" to include new disaster mitigation targets and measures.

Under the revised plan, the maximum estimated damage of about 18,000 deaths and 400,000 completely destroyed or burned buildings will be reduced to less than half of that number over the next decade. Because about 70% of the victims are expected to be fire related, the plan emphasizes fire control measures, such as seismic breakers, which automatically shut off electricity when they detect tremors, be largely installed.

This is the first revision since 2015. In recent years, with the advancement of AI and digitalization, urban and social structures, including telecom infrastructure, have changed significantly. The environment and situations around earthquake disaster management have also changed in a complex manner, posing increased risk during a major disaster. It is becoming more important to be prepared for a major earthquake that hits the overcrowded megacity with central functions.

Heavy damage in overcrowded megacity would paralyze national functions

About 36.9 million people, or about 30% of Japan's population, live in "Greater Tokyo Area," Tokyo and the surrounding three prefectures of Kanagawa, Saitama and Chiba, with about 9.65 million buildings, according to the Cabinet Office. The subsurface is a land-side plate (the North American Plate), under which the Pacific Plate and the Philippine Sea Plate overlap and subduct, a triple-layer plate structure that is rare globally. The Tokyo area is always at risk of a major earthquake.

According to the new damage estimates released by a government's working group in December last year, an inland earthquake in the south part of the capital (winter evening with winds of 8 meters per second) will cause about 18,000 deaths, including about 12,000 from fires and 6,000 from building collapses. About 130,000 completely destroyed and 270,000 burned-down buildings, totaling about 400,000 buildings.

In addition, about 4.8 million evacuees, about 13 million meals of food shortages at shelters, and power outage in about 16 million households, will cause economic losses of more than 83 trillion yen. Although the number of deaths is about 5,000 fewer than the damage estimated in 2013 and the number of completely destroyed or burned-down buildings is about 210,000 fewer, these figures are still far from the "roughly half" the government had set out in its 2015 emergency measures plan.

The revised plan expresses a sense of crisis in its opening that "If the central functions of the capital are impaired, not only will disaster response measures be greatly hindered, but also the lives and economic activities of the entire country will be impaired, and the impact may spread overseas" and that "The failure of the central functions of the capital may further escalate the enormous damage that will hit the overcrowded megacity." It also clearly states "building a system for uninterrupted central functions" and "maintaining lifelines and infrastructure functions" as key issues.

189 numerical targets for damage reduction

The revised plan clearly states that the numbers of deaths and completely destroyed or burned-down buildings would be reduced to less than half in 10 years. As a main feature, the plan sets targets with concrete figures to be achieved, rather than mere goals to strive for. The number of targets drastically increased from 47 to 189.

Another feature is that it emphasizes that there are limits to "public assistance" by the national and local governments, and that "self-help" and "mutual assistance" are also necessary. It points to "fostering awareness of disaster prevention and establishing a system throughout society" as urgent measures to be taken. It states, "We will shift from the idea of 'the government protecting the people, the people being protected,' to the idea of 'the people, businesses, communities, and governments dealing with disasters together.'"

Of course, "public assistance" by the government plays a major role. The national government is required to support local governments and educate citizens to achieve the targets. Nationals and citizens must make sure that the national and local governments implement policies and measures but also face the reality that governmental support is hardly available immediately after a major disaster. It is becoming increasingly important to ensure that each person is prepared as much as possible, once again.

Seismic breakers are key to fire protection

In the Great Hanshin-Awaji Earthquake and the Great East Japan Earthquake, more than half of the fires were caused by electrical systems, according to research. In Tokyo Inland Earthquake, fires also account for about 70% of the causes of the estimated numbers of deaths and completely destroyed or burned-down buildings. Thus, the revised plan greatly strengthened the fire control measures.

In particular, expanded damage by simultaneous multiple fires in winter poses the biggest threat, and the promotion of seismic breaker installation is positioned as a key measure. The plan states that the installation rate in emergency zones of Tokyo and nine prefectures (Ibaraki, Tochigi, Gunma, Saitama, Chiba, Kanagawa, Yamanashi, Nagano, and Shizuoka) will be raised from 20% in fiscal 2024 to "largely installed" by fiscal 2035.

Seismic breakers are the devices that prevent fires originating from wiring damaged by earthquakes, automatically shutting off electricity when they detect tremors. A breaker that shuts off electricity by detecting tremors with a built-in sensor on its panelboard requires electric work and costs up to 80,000 yen. There are simpler breakers that can be purchased for about 3,000 to 20,000 yen each.

Currently, some local governments subsidize the purchase, but in Tokyo, only about one-third of the municipalities provide subsidies (according to a survey by the Fire and Disaster Management Agency). In order to have breakers "largely installed," not only "self-help" but also expanded subsidies through "public assistance" is necessary.

Preventing fire occurrence alone is not enough as a fire control measure. The revised plan also includes a "100% elimination of extremely dangerous densely populated urban areas," but there are many issues to be solved for this, such as securing new places for residents. In addition, there are many measures and actions to be taken, such as securing firebreak zones and gradually shifting to highly fire-resistant buildings.

Seismic reinforcement of buildings is another key pillar. For a long time, the main target of seismic reinforcement measures has been to eliminate homes built before the 1981 "New Earthquake-Resistance Standards." However, it has become clear that the collapse rate of homes since the "2000 Standards," which were reinforced by lessons learned from the damage caused by the Great Hanshin-Awaji Earthquake, is low. The revised plan states that houses with insufficient earthquake resistance are to be "largely eliminated" in emergency measures areas by fiscal 2035. "Public assistance" is required here again.

Measures for evacuation and stranded people are also important

The number of evacuees is estimated to be up to about 4.8 million, which could lead to a shortage of shelters. Thus, the revised plan recommends sheltering at home and wide-area evacuation outside the affected areas. As the measures individuals can take, the plan sets a nationwide target of 100% households with at least 3-day emergency food and water supply by fiscal 2035 in the case of sheltering at home, as well as 100% furniture fixation.

It requests Tokyo and nine prefectures in the emergency measures area to create guidelines for the use of hotels and inns as shelters. Local governments are asked to have enough toilets, beds and other equipment to meet international standards. The plan also stipulates that municipalities in the emergency measures area should arrange meal provisions from private organizations.

In addition, the plan sets goals to increase the seismic reinforcement rate of water supply and transmission pipelines to 62%, sewer pipelines to 81%, and bridges on emergency transport roads to 90% by fiscal 2030. It also aims to promote seismic reinforcement of the power generation and transmission systems, and to widely strengthen the lifeline infrastructure such as by promoting cooperation on oil supply in the event of a disaster.

In the Great East Japan Earthquake, railway services were shut down and many people were stranded in central Tokyo. Roads were crowded with people and cars, hampering rescue efforts. In the Tokyo Inland Earthquake, some 8.4 million people are expected to be stranded, raising concerns for chaos. The revised plan urges avoidance of heading home all at once and to secure temporary accommodation including private facilities. It specifically lists a wide variety of measures, including the government's efforts to disseminate accurate information to prevent confusion due to false rumors spread on social media.

Perspective on disaster mitigation measures in the AI-digital society

The rapid spread of generative AI and other technologies have significantly changed our lives and accelerated "transformation of large cities into AI-digital societies." On the other hand, there are concerns that these cities are vulnerable to natural disasters such as major earthquakes. In the 1995 Great Hanshin-Awaji Earthquake, not only collapsed and damaged roads and buildings, but also vulnerable telecom infrastructures, such as telephone service outages, caused problems.

When an earthquake occurs directly under the capital, AI services will stop, cloud services will stop, cashless payment cannot be used, and government's digital services will not be available. Of course, data centers are seismically reinforced, but there is no guarantee that the entire system will be fully protected, including peripherals as well as long-term power supplies and complex communication networks. Interruptions and errors in GPS will also affect various areas such as logistics. Damages to these "invisible digital infrastructures" are highly likely to interfere with the central functions of the metropolitan area.

The revised Basic Plan for the Promotion of Tokyo Inland Earthquake Emergency Measure systemically covers detailed disaster mitigation measures. However, there are also many technical challenges in dealing with the vulnerabilities of "digital infrastructures," such as 5G communication networks and cloud computing, that are widely used in large cities, and "cyber physical system (CPS)" in the manufacturing, logistics, and transportation sectors.

An earthquake occurring directly under the capital is no longer just a natural disaster. It is also a "megacity system disaster" that directly hits the digital infrastructure that supports modern society. The question is how to strengthen "digital resilience," which includes not only seismic reinforcement and fire control measures but also electricity, telecom, and cloud data management, and how to protect the capital functions in the AI era. Preparations for the Tokyo Inland Earthquake have taken a new stage.