They're the other potential catastrophe at the Olympics. Organisers hope that any tremors will be small ones, but they're preparing for anything.
Long before the Covid-19 pandemic overwhelmed Olympic planners with the monumental task of preventing a superspreader event, another worst-case scenario loomed over the Tokyo Games.
Japan knows the risks well: Earthquakes, past and future, rarely stray far from the thoughts of Japanese. Entire government departments are dedicated to earthquake preparedness, schoolchildren and office workers are routinely put through practice drills, and architects and builders design skyscrapers meant to sway but not crumble.
Being ready is an everyday exercise because the inevitable is coming any day. The several earthquakes that are felt in central Tokyo every month, most barely noticed, are nudging reminders. In February, a large quake shook eastern Japan, reminding the country of the 10th anniversary of the devastating earthquake and tsunami that killed more than 19,000 people and triggered a nuclear meltdown in 2011.
The only certainty is that another big one is coming. But when? And what if it hits during the Olympics, or the Paralympics that follow?
No place appreciates the not-if-but-when dynamic more than Tokyo. Even without foreign spectators, there will be thousands of overseas athletes, coaches, staff members and media members concentrated in one of the world's largest and densest capital cities as the world watches what is designed to be a celebration of athletics and Japanese culture.
That poses a challenge to the organisers of Tokyo 2020, who even before the coronavirus pandemic were preparing for what is likely to be the hottest Olympics in history.
Local governments, schools, companies and the country's military prepare constantly for the threat of an earthquake, not to mention a tsunami or a typhoon. But Olympic visitors to the megalopolis — many who have never felt a quake, much less know what to do in a serious one — could introduce chaos and panic into even the most well-planned disaster response.
"Japanese people tend to have a base layer of knowledge when it comes to disasters," said Robin Takashi Lewis, a disaster specialist who worked with nonprofit groups during the aftermath of the 2011 earthquake and tsunami. But "things become 10 times more complicated when you add factors like language, lack of cultural understanding and the other vulnerabilities that people have as visitors."
All new buildings in Japan, including the Olympic venues, are subject to rigorous earthquake proof standards. New construction must be able to withstand an earthquake that measures 6.0 or more in degree of shaking on Japan's seismic scale.
In Tokyo, Akinori Fukao, chief of earthquake resistance in the urban buildings division of the Tokyo Metropolitan Government, said the government had worked with building owners to reinforce older structures, particularly along the city's main roads where planners were concerned about debris that might clog thoroughfares used by emergency vehicles.
Many of the Olympic venues are built on a landfill in Tokyo Bay, although officials at the Ministry of Land, Infrastructure, Transport and Tourism say they have protected against soil liquefaction — in which soil loses strength and stiffness — in the event of a severe earthquake.
But several venues, including the aquatics centre, have been built on land that sits below sea level, making them vulnerable to an earthquake-triggered tsunami, as occurred in 2011.
Tokyo Bay's shape, with a curved, narrow inlet that opens to a broad, expansive bay, is not conducive to major tsunamis, experts said. But not all venues are there. For example, the surfing site is along an unprotected stretch of Japan's east coast.
A wild card is the number of temporary venues being built solely for the Olympics, including large bleachers. Government engineers insist that even they will adhere to Japan's strict building codes, with extra reinforcements to handle earthquakes.
If there were an earthquake that measured 4 or higher on Japan's seismic scale — out of a possible 7 — the land ministry or Olympic organising committee would most likely call for a temporary suspension of the Games so that the agency's 12,000-plus engineers could check buildings for structural integrity.
Before the pandemic, when Japan expected to welcome hundreds of thousands of overseas visitors, a major concern was communicating earthquake protocols to officials, athletes and media members who might not react as calmly as the average Japanese. Imagine a stampede for the exits at any of the stadiums. While fans will be limited to Japanese people, and arenas will be at half-capacity, there will be tens of thousands of foreign athletes, coaches, officials and media members in attendance.
"If it was only for Japanese people we can say 'an earthquake has occurred,'" said Kazuki Matsumoto, an official at the land ministry, describing a common disaster announcement. "But maybe for foreigners we have to announce, 'An earthquake occurred, but it's OK, and please don't panic.'"
Several parks and office buildings around Tokyo have been designated as evacuation outposts for those who might not be able to get into their hotels. But it's not clear how visitors will know where to go.
With events across several regions — the marathon in Sapporo, baseball in Fukushima and surfing in Chiba — organisers will have to consider how to get visitors out of the country quickly in an emergency.
"Are people registering with their embassies when they arrive?" Lewis said. "Is there a system for tracking where people are staying?"
The land ministry has developed an earthquake preparedness and response app in 14 languages, and plans to put information posters in airports, train stations and hotels encouraging visitors to download it. But the risk messaging for the Olympics is more focused now on the coronavirus than earthquakes or other natural disasters.
Japan typically measures quakes using the Japan Meteorological Agency Seismic Intensity Scale, from 0 to 7. A 1 means that some people in a quiet room can feel it; a 3 is when most people inside can feel the swaying; a 5 is when dishes may fall from shelves and furniture may topple.
On average over the past five years, central Tokyo has had about 60 felt earthquakes (1 or higher on the intensity scale) every year, according to Naoshi Hirata, professor emeritus at the University of Tokyo and chairman of the earthquake research committee at the Headquarters for Earthquake Research Promotion. Only one of the 60 quakes over the past year reached an intensity rating of at least 4. An earthquake in February registered around 4 in Tokyo and 6 in Fukushima.
"So it's very likely to feel an earthquake during the Olympic Games," Hirata said. "But not necessarily a very devastating earthquake."
The challenges for Olympic organisers are matters of magnitude. The big one is unlikely, but small quakes are likely. What if an arena filled with mostly foreign officials and news media members starts to shake? What if athletes in the Olympic Village are shaken awake in their sleep? And what if it really is the big one?
Historically, major, damaging earthquakes hit the greater Tokyo area about once a generation, Hirata said. Using the Richter scale familiar to Americans, the earthquake research committee places a 70 per cent chance of a magnitude 7 or above earthquake in Tokyo in the next 30 years.
The last was in 1988, 33 years ago, but Hirata cautions that earthquakes are not regular events; Tokyo is not necessarily overdue. The next big one is just as likely to strike tomorrow as it was on the same date in 1988, he said.
"The chance of a very large earthquake in the period of the Olympic Games is very small as compared to the chance that Japanese people will be hit by such an earthquake in their lifetime," Hirata said. "Of course, there is still a chance because we have been hit many times here, and we should prepare for such a large earthquake."
Other Japanese scientists are more alarmist about the timing. Hiroki Kamata, professor emeritus of geoscience at Kyoto University, pointed out that a large earthquake struck the area now known as Tokyo in 878, nine years after the major Jogan earthquake and tsunami, which is often compared to the 2011 Great East Japan earthquake.
"We cannot say a quake will occur on a certain day in a certain month," Kamata said. "But we can calculate and say that such and such stresses are caused in the ground, and an earthquake will possibly hit a certain area around such and such time."
There is a history of Olympic-timed quakes in Japan. Just days before the 1964 Summer Games in Tokyo, The New York Times nonchalantly reported that a quake "rattled dishes."
After the major Kobe earthquake in 1995, which killed more than 6,000 people, some questioned whether it would hinder preparations for the 1998 Winter Olympics at Nagano. German Olympic officials wanted assurances that they would be safe.
On the opening day, a 6.6 earthquake was felt in Tokyo, but not at the Olympics, about 100 miles away.
But midway through those Winter Games, a magnitude-5 earthquake occurred near Nagano. The 10 seconds of shaking did not affect the competition but rattled beds, shook the press center and caused nearby high-speed trains to stop. (German skier Markus Eberle "kept his balance with no difficulty after the slight tremor, but he fell farther down the hill," The Times reported from the men's slalom.)
In 2018, Sapporo withdrew its bid for the 2026 Winter Olympics after a deadly earthquake hit the area, refocusing priorities.
This year, the Tokyo Games are being promoted as a way to help revitalise Fukushima, the area devastated by a nuclear meltdown after the 2011 earthquake and tsunami.
Rehearsing for disaster
Visitors may take comfort in the fact that Japan's preparation for emergencies is extensive, with multiple agencies holding annual drills that amount to elaborate dress rehearsals for disaster.
At a typical drill in the fall of 2019 in Tama, a Tokyo suburb, 500 emergency responders, medical professionals, members of the self-defense forces and volunteers staged an hour long simulation in muggy heat on a large set in the park. Multiple structures made from plywood had been made to look like they had just been hit by a massive earthquake.
Some buildings had subsided into mud, while others were painted with multiple large cracks. Helicopters hovered, lowering rescue workers in harnesses to pluck victims from a rooftop. A drone circled the damage. Fire engines, army trucks, ambulances and police officers on motorcycles sped in with crews to hose down flames or extract people trapped in rubble. Trained dogs sniffed for victims and explosives.
Elsewhere, doctors, nurses and even dentists practised treating college student volunteers who had been given prosthetic wounds or were instructed to act as if they had broken bones. Sewage workers demonstrated how they could erect a makeshift toilet over a manhole in less than five minutes.
"Japan has a lot of earthquakes and typhoons and there are a lot of risks and disasters," said Yoshiaki Satou, former director of disaster prevention planning and emergency services at the Tokyo Metropolitan Government, which oversaw the Tama drill. "And we don't know when they will come. We just know these disasters will definitely occur at some time."
"We are working," he said, "to prepare for anything to be OK."
This article originally appeared in The New York Times.
Written by: John Branch and Motoko Rich
Photographs by: Chang W. Lee and Hiroko Masuike
© 2021 THE NEW YORK TIMES