3rd April 2024 – (Tokyo) The shaking started just before 8am local time today, when a powerful magnitude-7.2 earthquake struck offshore just south of Taiwan’s east coast. The tremors were felt across the island, damaging dozens of buildings and prompting tsunami warnings that extended as far as Japan and the Philippines. At least nine people were killed and over 800 injured in what was described as the strongest quake to hit Taiwan in at least 25 years.

For years, seismologists have warned that Japan’s capital Tokyo is overdue for a catastrophic earthquake, one that could devastate the world’s most populous metropolitan area. Recent events in Taiwan have only heightened concerns that Tokyo’s own “Big One” may be next on the agenda.

The 1st January 2024 magnitude-7.6 earthquake that struck the Noto Peninsula in northwest Japan, killing 244 and injuring over 1,200, was a desolate reminder of the seismic threats facing the region. Now, with Taiwan’s east coast still reeling, the prospect of Tokyo being the next domino to fall has become an increasingly urgent concern.

Japan’s capital sits precariously atop one of the most seismically active regions on Earth. Lying directly on the boundary between the Eurasian and Pacific tectonic plates, the Tokyo metropolitan area is constantly under threat from the powerful, lurching movements of these colossal crustal blocks. Experts estimate there is a 70% chance of a magnitude-7 or greater quake hitting the city within the next 30 years.

When it does arrive, the impact will be catastrophic. A magnitude-7.3 earthquake striking just north of Tokyo Bay could kill nearly 10,000 people and injure 150,000 more. Over 300,000 buildings could be destroyed, and a staggering 5.2 million people could be left stranded, unable to return home. The last time a disaster of this scale struck Tokyo was in 1945, when U.S. firebombing raids levelled large swaths of the city and killed over 100,000.

Though Tokyo has transformed dramatically since the devastating Great Kanto Earthquake of 1923, which killed 105,000, the city remains highly vulnerable. Its densely packed urban core of ageing wooden buildings and narrow streets is a tinderbox waiting to erupt. And with millions of tourists expected for major events like the 2024 Rugby World Cup and 2025 Olympics, the potential for panic and chaos in the aftermath of a big quake is immense.

“Japan is world famous for its resilient infrastructure and seismic technologies, but my concern is preparedness at the community and individual level,” says Robin Takashi Lewis, a Tokyo-based disaster preparedness expert. “When you have a city this big and your basic lifelines are out, that’s a very significant problem.”

Indeed, even Tokyo’s most advanced earthquake-proofing measures would be overwhelmed by the sheer scale of destruction from a magnitude-7 or greater quake. The city’s sprawling network of hi-tech, sway-resistant skyscrapers may avoid catastrophic collapse, but the damage to critical infrastructure like electricity, gas, and water supplies could leave millions stranded for weeks. With the emergency services certain to be swamped, Tokyo’s residents may have to rely on their own wits and community resources to survive in the chaotic aftermath.

“In the case of the ‘big one’, the Tokyo inland earthquake, the emergency services would be overwhelmed,” warns Lewis. Authorities have designated over 3,000 schools, community centres and other public facilities as evacuation shelters, but with millions displaced, these would be quickly overwhelmed.

Tokyo has learned hard lessons from past disasters. After the Kobe earthquake of 1995, the city strengthened building codes and invested billions in flood defences and other protective infrastructure. But the threat of the “Big One” looms ever larger, especially as climate change brings more extreme weather that could compound the damage.

Faced with this dire prospect, Tokyo’s residents have little choice but to brace themselves. The city government has distributed a 338-page disaster preparedness manual to 7 million households, outlining survival strategies and advice like securing furniture and stockpiling emergency supplies. Schools and companies routinely hold earthquake drills. The daily chime of the “Yuyake Koyake” children’s song serves as a daily reminder that the ground could start shaking at any moment.

Yet for all its meticulous planning, Tokyo remains acutely vulnerable. The next big earthquake may be just around the corner, and when it strikes, the city will be tested like never before. As the people of Taiwan and Japan’s Noto Peninsula have learned, the shaking can come without warning, and the damage may be beyond anyone’s ability to fully prepare. For Tokyo, the “Big One” may be imminent – the only question is whether the city will be ready when the earth starts to move.