TOKYO — The Japan Meteorological Agency issued and quickly retracted an emergency earthquake warning on Friday after mistakenly estimating that a massive magnitude-9.9 earthquake had struck the Chishima Islands off Hokkaido’s coast.
The false alert went out at 12:40 p.m., forecasting that Hokkaido and northeastern Japan’s Tohoku region would experience tremors reaching the maximum level 7 on the country’s seismic intensity scale. Officials rescinded the warning just eight minutes later at 12:48 p.m.
The actual seismic event, originating near the Kamchatka Peninsula, measured a magnitude of 6.9 and caused a mild seismic intensity of 1 in Hakodate, Hokkaido.
“We deeply apologize for causing great inconvenience,” Ayataka Ebita, director of the agency’s Earthquake and Tsunami Observation Division, stated during a news conference.
Ebita noted that investigators found no evidence of an external cyberattack, pointing instead to a probable malfunction within the computer software processing system. The agency is actively reviewing why the system calculated an implausible magnitude of 9.9, noting that the largest recorded earthquake in history was a 9.5 magnitude tremor in Chile in 1960.
In response to the false alarm, the Hokkaido Railway Company (JR Hokkaido) temporarily halted operations on several local train lines.
The incident recalls a similar system error on August 8, 2013, when a minor magnitude-2.3 earthquake in Wakayama Prefecture triggered a false warning for a magnitude-7.8 quake in Nara due to an underwater seismometer malfunction off Mie Prefecture.