In a bizarre incident, Japan’s Meteorological Agency (JMA) issued a warning about what could have been the world’s worst earthquake ever. The agency retracted the warning a few minutes later, but it still alarmed large parts of the country and unsettled people who had witnessed horrifying disasters.
The JMA estimated a magnitude 9.9 earthquake in the Kuril Islands off Hokkaido on October 16, 2026, but quickly rescinded the alert on account of an error.
The early-warning system had incorrectly placed the earthquake’s epicenter in the Kuril Islands (Chishima Islands) off Hokkaido and calculated a magnitude of 9.9. However, JMA officials later said the system wrongly assumed the quake was about 680 kilometers farther from Japan than it actually was, near Russia’s Kamchatka Peninsula.
The JMA, which has a near-flawless warning system, warned that Hokkaido and the Tohoku region in northeastern Japan would experience shaking up to 7, the highest intensity on the country’s seismic scale. However, a magnitude 6.9 earthquake near Russia’s Kamchatka Peninsula produced only intensity 1 shaking in Hakodate, Hokkaido.
The JMA withdrew the alert just eight minutes after issuing it, marking the first full public retraction of an emergency earthquake warning.
Officials said the magnitude was overstated because its computer system misidentified the earthquake’s focus, though they ruled out a cyberattack. Some local reports noted that one contributing factor may be applying magnitude-calculation methods designed for earthquakes within Japan’s dense observation network to a distant event outside coverage.
Ayataka Ebita, director of the agency’s Earthquake and Tsunami Observation Division, apologized to the public at a news conference, saying, “We deeply apologize for causing great inconvenience.” Meanwhile, Chief Cabinet Secretary Minoru Kihara told reporters that the government regretted the incident. “We caused a great deal of worry and placed a burden upon those who took shelter or took action to ensure their safety, as well as on others such as transport systems and businesses that were affected,” he said.
Several Japanese citizens had learned about the alert through municipal public address systems, TV and radio broadcasts, or their smartphones.
As expected, the false alarm sparked chaos in several parts of the country, disrupting daily life and domestic transit. In Sapporo, Hokkaido, for example, 14 trams stopped for a few minutes after the warning until their operator decided it was safe to continue service. Additionally, bullet train operations between Shin-Yokohama and Toyohashi stations on the Tokaido Shinkansen Line were briefly halted, although the operator later noted that the suspension was not directly caused by the earthquake warning.
Moreover, people sought shelter unnecessarily in some places, and social media later buzzed with netizens expressing confusion after the alert was retracted.
A false magnitude-9.9 earthquake warning jolted people because it is exceptionally scary, and no instrumentally recorded earthquake has ever reached magnitude 9.9.
According to publicly available information, the largest instrumentally measured earthquake in history—magnitude 9.5—was the 1960 Valdivia earthquake in Chile that killed more than 1,600 people, injured at least 3,000, and left two million people homeless. The rupture zone stretched 500 to 1,000 kilometers along the country’s coast.
A rupture zone is the area along a fault or rock mass where stress exceeds the material’s strength, causing it to break or fracture during an earthquake.
The false warning could have triggered panic because Japan’s geography puts it in an area of extreme seismic risk. Japan sits at the convergence of four major tectonic plates—Pacific, Philippine Sea, Eurasian, and North American—along the Pacific “Ring of Fire,” making it one of the most earthquake-prone places on Earth.
In fact, about 20% of the world’s magnitude-6.0 or larger earthquakes occur in or around Japan.
Initially, the system located the epicenter near the Kuril Islands off Hokkaido, where a possible magnitude-9-class event is believed possible. Official scenarios for such an event have earlier predicted tsunami heights of up to 30 meters in some places; possible death tolls of close to 100,000; and widespread destruction of buildings and infrastructure.
The so-called erroneous warning predicted intensity 7 shaking across northern Japan. If it had come true, nearly all buildings would have suffered severe or total damage, and landslides, ground cracks, and infrastructure collapse may have occurred.
In a country where even moderate earthquakes bring an otherwise bustling country to a standstill by triggering automatic train halts, elevator shutdowns, and immediate public action, a maximum-intensity alert over such a wide area may have shaken the people.
The eight minutes that the alert was live may have brought back the trauma of 2011 when Japanese people stood witness to the worst natural disaster to hit the country.
The Shadow of the 2011 Disaster
In 2011, Japan suffered its worst natural disaster when a magnitude 9.0 to 9.1 megathrust earthquake struck off Tohoku’s Pacific coast, about 130 kilometers east of Sendai.
The earthquake hit on March 11, 2011, at 2:46 p.m. local time. On that fateful day, a massive undersea megathrust earthquake measuring 9.0–9.1 occurred in the Pacific Ocean some 72 kilometers east of the Oshika Peninsula in Japan’s Tohoku region.
According to publicly available information, the quake was relatively shallow, at about 24-32 kilometers deep, and lasted six minutes. However, it was so violent that it shifted the seafloor and generated a series of powerful tsunami waves.
The waves hit the coast about 30 to 40 minutes after the main shock, toppling seawalls and inundating about 561 square kilometers of land along Japan’s northeastern Pacific coast. In places such as Miyako, these waves attained a maximum run-up height of 133 feet.
The tsunami swept entire towns and coastal communities in Iwate, Miyagi, and Fukushima prefectures, among others, leaving widespread devastation.
Following the tsunami, hundreds of people were reported dead, and hundreds more were reported missing.
As rescue efforts began and the scale of the destruction—particularly in coastal areas—became apparent, the numbers in both categories sharply increased. After two weeks of the disaster, about 10,000 people were officially counted as deceased by the Japanese government, and about 1.5 times as many were still listed as missing and believed dead.
Finally, the official Japanese government or Reconstruction Agency figures were reported to be more than 19,729 dead, more than 2,553 missing, and about 6,200 injured.
The vast majority of fatalities resulted from drowning in the tsunami rather than the earthquake shaking itself. Over 120,000 buildings were completely destroyed, with hundreds of thousands more severely or partially damaged. Furthermore, the disaster also severely damaged and disrupted critical infrastructure, including roads, railways, ports, airports, power lines, and water systems.
Adding to this massive toll on the country’s people and economy, the disaster also triggered a major nuclear accident at the Fukushima Daiichi Nuclear Power Plant.
Although the earthquake triggered an automatic shutdown of the reactors, floodwaters inundated the facility and disabled both off-site power lines and emergency diesel generators. Without cooling, three reactor cores melted down, triggering hydrogen explosions and releasing radioactive material, which sparked evacuation en masse.
The event was subsequently rated Level 7 on the International Nuclear Event Scale—the highest level, shared only with the 1986 Chornobyl disaster.
The earthquake and tsunami following the disaster had long-term social, economic, and environmental impacts across northeastern Japan. In fact, recovery and reconstruction from the accident took more than a decade, including rebuilding communities, infrastructure, and coastal defenses, and managing the Fukushima site going forward.
Against this background, the recent false warning was uniquely unsettling because it briefly presented the public with a scenario worse than 2011, as it would have released roughly 20 times or more the energy of the Tohoku quake. Moreover, the predicted location lies along the same subduction zone system that produced the 2011 disaster.
The recent false alarm did not trigger an earthquake, but it may have forced the country to briefly confront the scale of another possible disaster.
- Contact the author at sakshi.tiwari13 (at) outlook.com
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