Tachikawa and Tokyo’s Next Big Earthquake: Disaster Base Guide

If a major quake hits Tokyo, the state turns to Tachikawa. A new 46.5-billion-yen disaster base, a velodrome shelter, and what visitors should know.

日本語で読む（Japanese version）

In the Great Kanto Earthquake of 1923, the collapse rate in Tachikawa (立川), counting buildings totally destroyed, was zero per cent.

So says the page on the Tachikawa fault zone on the city’s official website. To be precise, it is a record of a city official visiting a university professor who had sat on the government’s Earthquake Research Committee, and of the professor saying that the Musashino Plateau is good ground, and that Tachikawa’s zero collapse rate in the Great Kanto Earthquake proves it. The city’s local-history booklet Tachikawa Monogatari (Tales of Tachikawa) records that, in the wake of that earthquake, the aviation departments of newspaper companies and others moved from Suzaki, in what is now Koto Ward, to the airfield at Tachikawa. An inland plateau to be relied on after a great shaking. For a hundred years, Tachikawa has carried that role.

That Tachikawa now holds the national government’s backup facility for its disaster headquarters, I wrote in this series’ piece on the disaster-prevention learning centre. When the Prime Minister’s Office, the Cabinet Office and the Ministry of Defense can’t be used, the government’s disaster headquarters is set up in Tachikawa. The capital’s spare brain.

But will the spare always stay a spare? At the end of 2025 the state revised its damage estimates for an earthquake directly beneath the capital, and in early summer 2026 it changed its basic plan of countermeasures. The Tokyo Metropolitan Government drew up a plan to build a disaster base in Tachikawa more than twice the size of the present one. The city of Tachikawa decided to make its keirin velodrome an evacuation shelter. How will Tachikawa’s role in supporting the capital change from here? Carrying a bundle of documents, I set out to walk Tachikawa’s “next”.

The new estimates for an earthquake beneath the capital, and Tachikawa’s role

Japan prepares for a major earthquake directly beneath the Tokyo area, which the government calls the “Tokyo Inland Earthquake” (Shuto Chokka Jishin). Let me start with the national numbers. On 19 December 2025, a working group of the Central Disaster Management Council published a report with new damage estimates and countermeasures for that earthquake. At the centre of the estimates it put the scenario that would cause the most damage: an earthquake of magnitude 7.3 directly beneath southern central Tokyo.

In the worst case, about 18,000 people die, about 12,000 of them because of fire. About 400,000 buildings are totally destroyed or burned. About 4.8 million people are evacuated, and about 8.4 million are unable to get home. Separately, disaster-related deaths are estimated at about 16,000 to 41,000. About 70% of deaths and of buildings destroyed or burned are caused by fire, the national documents state plainly.

In response to the report, on 12 June 2026 the government changed its Basic Plan for the Promotion of Emergency Countermeasures against the Tokyo Inland Earthquake. It was the first major review in about ten years since the plan was drawn up in March 2015. Over the next ten years, the expected number of deaths and the number of buildings destroyed or burned are each to be cut to half or less: that became the new disaster-reduction target. The number of concrete targets rose fourfold, from 47 to 189. Even the share of households that keep at least three days’ food, and the installation rate of seismic circuit breakers, are now on the ruler.

If 70% of deaths come from fire, then keeping fires from breaking out after the shaking saves the most lives. A seismic circuit breaker, which cuts the electricity when it senses an earthquake, is a tool for exactly that. The city of Tachikawa, too, in its 2026 revision of its local disaster management plan, lists promoting the installation of seismic circuit breakers, and drawing up plans for running evacuation shelters, as examples of preventive measures to pursue together with residents. The national ruler and the city’s measures point the same way.

So where does Tachikawa sit in this plan?

A brief recap of how Tachikawa came to carry this role. In 1977 the US forces’ Tachikawa Airfield was fully returned, and in 1979 a national council recommended that the site be used for “two pillars”: a large park and a wide-area disaster-prevention base. One became Showa Kinen Park (Showa Memorial Park); the other became the Tachikawa Regional Disaster Prevention Base. I wrote more about this in the piece on the learning centre.

The Government Business Continuity Plan, adopted by the Cabinet in March 2014, sets the order of places where the government’s emergency disaster headquarters will be set up in a Tokyo Inland Earthquake. If the Prime Minister’s Office can’t be used, then the Cabinet Office, the Ministry of Defense, and then the backup disaster headquarters facility at the Tachikawa Regional Disaster Prevention Base, in that order. The same plan contains another important sentence. When alternative offices for central ministries are set up outside central Tokyo, the area around the Tachikawa Regional Disaster Prevention Base is to be considered first; and even when alternative offices are set up elsewhere, such as Saitama Shintoshin, securing communications and transport routes with Tachikawa is to be taken into account. The nation’s spare brain is also the meeting point for the ministries’ spare brains.

But the story doesn’t end there. The working group’s report assesses the progress of the past ten years like this. On government business continuity, the targets for the command structure, the working environment and securing alternative bases were broadly achieved. On the other hand, “securing backup functions outside the Tokyo area” was pointed out as an issue. The 2026 basic plan, too, says it will consider alternative bases even for the worst case, in which the capital’s core functions cannot be maintained within the Tokyo area, with details to be set out in the Government Business Continuity Plan.

Tachikawa is about 30 kilometres from central Tokyo, but it is inside the Tokyo area. If you consider a situation where the Tokyo area itself cannot function, you need a spare for the spare, further out than Tachikawa. National discussion has now come that far. Does that make the spare brain’s role lighter? I don’t read it that way. Even if functions are moved outside the Tokyo area, you first need a place to take the strain of the first few days and connect with the outside. As that first catcher, Tachikawa’s weight may well increase. That is my own view.

While the national plan thinks about the “brain”, the Tokyo Metropolitan Government is setting out to rebuild the “hands and feet” in Tachikawa.

Tokyo’s new disaster base: a 46.5-billion-yen building on the site of a rice warehouse

The “Basic Plan for Developing a New Disaster Prevention Base for the Tama Area”, drawn up by the Tokyo Metropolitan Government in January 2026, is, I think, the document that most concretely describes the “next” of disaster preparedness in Tachikawa. (Tama is the long western half of Tokyo beyond the 23 central wards.)

It covers two metropolitan facilities inside the Tachikawa Regional Disaster Prevention Base. One is the Tachikawa Regional Disaster Prevention Center, completed in 1991 (Heisei 3). In a disaster it is the Tama base for gathering information, stockpiling supplies and securing personnel under the command of the disaster prevention centre at the Tokyo Metropolitan Government Building, and it is also designated as the backup for that centre. The other is the Tama Wide-Area Disaster Prevention Warehouse next door, a building the state put up in 1990 as a rice stockpile warehouse, the “Tachikawa Government Warehouse”, and which Tokyo acquired in 2016. I touched on the warehouse’s history in the learning centre piece, so here I will write about what happens to it next.

The metropolitan plan combines the functions of the two facilities into one. The current Tama Wide-Area Disaster Prevention Warehouse will be demolished, and on its site a “new disaster prevention base” will be built that combines the functions of the disaster prevention centre with those of a stockpile warehouse and wide-area transport base. Total floor area about 50,000 square metres. One basement floor and four above ground, about 28 metres high. The estimated project cost, demolition, design and construction together, is about 46.5 billion yen.

Line up the numbers and you can see the scale of the change. The disaster headquarters and office rooms grow tenfold, from about 400 square metres now to about 4,000. Capacity is planned at about 550 people. What’s interesting is a line the plan adds for reference: the headquarters and office rooms for the disaster prevention centre function at the Tokyo Metropolitan Government Building cover about 2,000 square metres. The new Tachikawa base will have twice that. The spare room is bigger than the rooms at the main house. That must mean the “day the main house can’t be used” is being imagined in earnest.

Rooms for staying overnight and napping cover about 3,200 square metres, sleeping about 280 people. Storage for supplies goes from about 11,200 square metres to about 16,000. The amount that can be shipped out in a day nearly triples, from about 1,800 pallets to about 5,000. The building is to be designed to receive “push-type support”, in which the state sends supplies without waiting for requests from the disaster area, with a structure that lets 10-tonne trucks unload directly.

The old warehouse still bears traces of its days as a rice store. The plan notes that removing the storage installations left inside, the silos, would allow the space to be used effectively. A building where the nation’s rice once lay will be torn down and reborn as a building that supports the lives of Tokyo’s people. Here too there are three stages: back then, now, and next.

The plan also contains a slogan that is easy to remember: “HTT”, from the initials of the Japanese words for “reduce”, “make” and “store” electricity (herasu, tsukuru, tameru). Cut the electricity used with insulation and natural light, make electricity with solar panels on the roof, store it in batteries and use it for the outdoor lights at night. The disaster base becomes, at the same time, a model of decarbonisation. A name very much in the style of an office fond of romanised abbreviations, but the meaning is sound.

The preparations for electricity are thorough too. It will take power from two separate grid lines (“dual-circuit power receiving”), and for emergency generation, in addition to oil, a medium-pressure gas pipe will be laid so it can generate with gas as well. For earthquake resistance it aims at the highest level in the national standards for government buildings: a building that can keep being used after a large earthquake without repairs to its structure.

The supply base can’t be left empty during construction either. The metropolitan government will secure about 25,000 square metres of land in nearby Fujimicho, Tachikawa, set up a temporary facility, move the supplies there, and then demolish the old warehouse. Another roughly 6.3 billion yen is expected for this temporary facility. In the plan’s schedule, the fiscal 2025 basic plan is followed by basic design and detailed design; then the supplies move to the temporary facility, the old warehouse is demolished, and construction of the new base begins. Completion is scheduled within fiscal 2033 (Reiwa 15). (Reiwa is the current imperial era, which began in 2019.)

But the plan attaches its own caveats. The project cost is a current estimate and will be examined closely at the design stage while watching construction prices. The completion date, too, will be re-examined at the design stage. In an age of continuing increases in materials prices, nobody knows whether the 46.5-billion-yen figure will hold. It will probably be one of the points of debate from here on.

The new base is not a building only for the day of a disaster. The metropolitan plan says that in normal times it will serve as the Tama area’s “disaster prevention hub”, handling disaster-prevention consultations from nearby municipalities together and holding overnight drills and training with local governments and related bodies. It also plans drills, with the state and transport companies, to actually run the warehouse. A base that isn’t used in ordinary times won’t move when it counts either. That obvious truth is built into how the building will be used.

The current Tachikawa Regional Disaster Prevention Center, whose job will end, has a next job in view too. The idea under consideration is to use it in normal times as a facility where Tokyo residents learn about and experience disaster prevention, or as a satellite office, and in a disaster as working space for the metropolitan government’s bureaus.

Tachikawa and the next big Tokyo earthquake, in numbers

• 0% — Tachikawa’s collapse rate (total destruction) in the Great Kanto Earthquake, in the words of the expert quoted on the city’s page. Thanks to the ground. Not the residents’ achievement, but they’re allowed to boast about it.
• 4th — Tachikawa’s place in the order of locations for the national emergency disaster headquarters. After the Prime Minister’s Office, the Cabinet Office and the Ministry of Defense.
• about 4,000 square metres — the headquarters and office rooms at Tokyo’s new disaster base. About twice the same function at the Tokyo Metropolitan Government Building.
• about 46.5 billion yen — the estimated cost of the new disaster base. Plus about 6.3 billion yen for the temporary facility.
• fiscal 2033 — scheduled completion (within Reiwa 15). Roughly when a child now in the first year of primary school will be in the second year of junior high.
• 140 — citizens’ disaster-prevention organisations in Tachikawa as of April 2026. However fine the national and metropolitan plans, the people knocking on the neighbours’ doors in the first few hours will be the people of these 140 groups.

Traveller’s detour quiz

The metropolitan basic plan sets out the conditions of the site for the new disaster base in a table. In the “height restrictions” row, alongside the local building-height district rules, which other restriction is listed?

• A: a height restriction under a landscape ordinance
• B: a height restriction under the Civil Aeronautics Act
• C: a height restriction for the protection of cultural properties

The answer comes near the end of this article.

We have looked at the big national and metropolitan plans. But on the night an earthquake strikes, the places Tachikawa’s people actually head for are much closer to home. A keirin velodrome, for example.