Major Earthquakes Are Occurring Frequently Across the Country… Experts Explain! What Would Happen If One Struck a Major Metropolitan Area?
[Part 1] Earthquakes with a seismic intensity of 5- or higher are occurring at a rate exceeding last year’s
Signs of a Major Earthquake
On June 25, an earthquake with a seismic intensity of 6+ struck Aomori Prefecture, followed by one with a seismic intensity of 6- in Yamanashi Prefecture the next day, June 26.
Major earthquakes are now occurring frequently across the country. Last year, there were 15 earthquakes with a seismic intensity of 5- or higher. This year, there have already been 13—a pace that exceeds last year’s total (as of July 12). Hiroki Kamata, an authority on Earth sciences and professor emeritus at Kyoto University, explains.
“Since the Great East Japan Earthquake in March 2011, the crust in the seas off Japan has become unstable. Additionally, the influence of the massive Nankai Trough earthquake—which is predicted to occur around 2035—is growing.In past instances of the Nankai Trough mega-earthquake, major earthquakes have frequently occurred inland starting about 40 years before the main event. In recent years, the Great Hanshin-Awaji Earthquake in January 1995 and the Kumamoto Earthquake in April 2016 are believed to fit this pattern.”
As mentioned earlier, major earthquakes with a seismic intensity of 6 or higher and a magnitude (M) of 7 or greater have been occurring frequently. However, while earthquakes in Aomori, Yamanashi, and other areas damaged about 800 buildings and injured nearly 40 people, there were no fatalities. Why is that? Mr. Kamata explains.
“The location of the epicenter is the main reason. It’s because they were far from densely populated areas.”
The epicenter of the Aomori earthquake was off the coast of Iwate Prefecture, while that of the Yamanashi earthquake was in the eastern region of the Fuji Five Lakes. What would happen if a major earthquake with a seismic intensity of 6 or higher and a magnitude (M) of 7 or higher struck a major metropolitan area such as Tokyo, Nagoya, or Osaka? If, as with the earthquake that occurred in June, the epicenter were far from where people live, the damage might be minimal. However…
“It’s a different story if it’s a direct-hit earthquake occurring directly beneath a city. The government’s Central Disaster Prevention Council and local governments have issued damage estimates for the scenario of a direct-hit earthquake occurring in their respective cities, and the damage would be catastrophic.While the exact figures vary depending on the season, time of day, and wind strength, it is estimated that a quake with a maximum seismic intensity of 7 could result in anywhere from several thousand to over 40,000 fatalities. The primary causes of death are expected to be building collapses and fires.”
From the July 31, 2026 issue of *FRIDAY*
PHOTO： Kyodo News