Japan's Meteorological Agency (JMA) issued and then withdrew, within about eight to twelve minutes, an emergency warning for a magnitude-9.9 earthquake on October 16, 2026. The actual quake, centred off Russia's Kamchatka Peninsula, was later confirmed by seismologists at magnitude 6.9, with JMA blaming a data-processing error rather than a cyberattack.
Japan's Meteorological Agency (JMA) issued an emergency earthquake warning on October 16, 2026, stating that a magnitude-9.9 earthquake had struck near the Kuril Islands at a depth of about 140 kilometers. The warning, which forecast maximum-level shaking across a large stretch of Japan, was withdrawn within minutes after JMA determined the figure was wrong.
What happened, minute by minute
According to a timeline reported by the seismic monitoring site The Watchers, a magnitude-6.9 earthquake actually occurred near Kamchatka at 12:38 Japan Standard Time (JST). JMA's automated system detected the seismic waves at 12:38:10 JST. An intermediate estimate about 34 seconds later, at 12:38:44 JST, put the magnitude at 7.3, but by 12:39:23 JST the system's estimate had escalated to 9.9. The first public emergency warning carrying that figure went out at 12:40:02 JST, followed by a second update at 12:40:41 JST that retained the 9.9 reading. The warning was withdrawn at 12:48 JST, roughly eight minutes after the first alert.
The withdrawn warning had projected intensity level 7 — the maximum on Japan's seismic intensity scale — across areas stretching from Hokkaido in the north to the Chubu region in central Japan, including Tokyo, according to The Watchers. The actual maximum intensity observed anywhere in Japan was level 1, recorded in Hakodate, Hokkaido.
Trains halted, no tsunami warning
The false alert triggered automatic safety systems on the Tokaido Shinkansen bullet-train line. Power was cut between Shin-Yokohama and Toyohashi stations for about 15 minutes, with services resuming around 13:00 JST, though some westbound delays continued until 15:45 JST, The Watchers reported. BNO News, citing JMA, said no tsunami warning was issued and no actual shaking tied to the erroneous alert was recorded in Japan.
JMA's explanation
At a press conference held at 14:00 JST, JMA apologized and said it had "substantially overestimated the earthquake magnitude," according to The Watchers. The agency said the mistake stemmed from an error in its automated data-processing chain rather than a hardware malfunction, and that the precise cause remained under investigation. Officials also said the earthquake's distance from Japan's monitoring network may have contributed to the miscalculation.
Ayataka Ebita, director of JMA's Earthquake and Tsunami Monitoring Division, was quoted by The Watchers explaining that earthquakes near Kamchatka fall outside the immediate coverage of Japan's domestic seismic stations.
The agency's northernmost observation coverage extends approximately to the Nemuro region of Hokkaido, leaving earthquakes near Kamchatka outside the immediate coverage of its domestic seismic stations.
— Ayataka Ebita, JMA Earthquake and Tsunami Monitoring Division
JMA also ruled out a cyberattack. System administrators found no indicators of outside interference with the agency's monitoring network, The Watchers reported.
What the real earthquake measured
The U.S. Geological Survey recorded the actual earthquake at magnitude 6.9, located about 76 kilometers northeast of the settlement of Ozernovskiy on Russia's Kamchatka Peninsula, according to BNO News, which reported a depth of 143.2 kilometers. No tsunami was generated.
False alert vs. confirmed earthquake
Detail
JMA initial warning
Confirmed reading
Magnitude
9.9
6.9 (USGS, per BNO News)
Depth
~140 km
143.2 km (USGS, per BNO News)
Location
Kuril Islands (estimated)
~76 km NE of Ozernovskiy, Russia
Max. intensity forecast for Japan
Level 7 (maximum)
Level 1 observed (Hakodate)
Tsunami warning
None issued
None issued
Why the error mattered
A magnitude 9.9 earthquake would be the largest ever instrumentally recorded, exceeding the magnitude-9.5 Valdivia earthquake that struck Chile in 1960, according to figures cited by BNO News. Because the Richter-type magnitude scale is logarithmic, a 9.9 reading corresponds to roughly 32,000 times more released energy than an actual magnitude-6.9 event, BNO News reported, illustrating why even a brief false alert can trigger large-scale precautionary shutdowns such as the Shinkansen's automatic braking system.
Regional reaction
The false warning coincided with the Aichi-Nagoya Asian Para Games, according to Korean outlet StarNewsKorea, which reported that the incident added to pre-existing criticism of event organization tied to the preceding Asian Games. The outlet quoted commentary describing the false alarm as fueling distrust, while noting JMA's public apology at the press conference.
Questions
How long was Japan's false magnitude-9.9 alert active before it was withdrawn?
Reports vary slightly: The Watchers timed the withdrawal at about eight minutes after the first warning (12:40 to 12:48 JST), while other outlets cited nine to twelve minutes depending on which alert update is used as the starting point.
What was the real magnitude of the earthquake?
The U.S. Geological Survey measured the actual earthquake at magnitude 6.9, centered roughly 76 kilometers northeast of Ozernovskiy on Russia's Kamchatka Peninsula.
Did Japan's false alert cause a tsunami warning?
No. JMA did not issue a tsunami warning in connection with either the false 9.9 reading or the confirmed 6.9 earthquake.
What caused the magnitude to be miscalculated?
JMA said the error occurred during its automated data-processing chain, not from a hardware failure, and that the earthquake's distance from Japan's seismic monitoring network may have contributed. The agency said the precise cause remained under investigation and explicitly ruled out a cyberattack.
Did the false alert cause any real-world disruption in Japan?
Yes. The Tokaido Shinkansen's automatic earthquake-safety system cut power between Shin-Yokohama and Toyohashi for about 15 minutes, with some delays lasting into the afternoon, though no actual damaging shaking occurred in Japan.
How the world is telling it
KoreanStarNewsKorea framed the false alert as occurring during the Aichi-Nagoya Asian Para Games and linked it to broader criticism of event organization following the preceding Asian Games, describing the incident as deepening existing distrust rather than focusing solely on the technical failure.
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