Japan Withdraws Erroneous Magnitude 9.9 Earthquake Alert After Eight Minutes as Meteorological Agency Investigates

October 16, 2026

Japan’s Meteorological Agency issued an emergency earthquake warning on Friday after its system mistakenly estimated a magnitude 9.9 earthquake near the Kuril Islands, triggering alerts across parts of the country. The warning was withdrawn approximately eight minutes later after authorities determined that the initial estimate was erroneous.

The agency said its earthquake-warning processing system had significantly overestimated the magnitude and incorrectly assessed the source of the seismic event. The cause of the error remains under investigation.

The alert did not correspond to an actual magnitude 9.9 earthquake. A separate earthquake of approximately magnitude 6.9 occurred near Russia’s Kamchatka Peninsula, according to reports citing seismic monitoring data.

Emergency Alerts Trigger Alarm Across Japan

At around 12:40 p.m. local time on October 16, Japan’s Meteorological Agency issued an emergency earthquake warning, initially estimating a magnitude 9.9 event near the Kuril Islands. The system forecast the possibility of severe shaking, including the highest level on Japan’s seven-point seismic intensity scale.

The warning covered areas extending from Hokkaido to central Japan, including parts of the Tohoku, Kanto, Koshin, Hokuriku and Tokai regions. Emergency notifications appeared on mobile phones, while public alert systems also sounded, prompting concern among residents.

At approximately 12:48 p.m., the agency withdrew the warning. Actual shaking was far weaker than initially predicted, with Hakodate in Hokkaido recording a seismic intensity of just 1 on Japan’s scale.

Reports indicated that no shaking consistent with a magnitude 9.9 earthquake had occurred. No tsunami warning was issued in connection with the incident.

A Real Earthquake Occurred, but Its Magnitude Was Greatly Overestimated

According to information released by the Meteorological Agency, its warning system initially located the earthquake near the Kuril Islands and estimated its magnitude at 9.9. The agency acknowledged that the magnitude had been substantially overestimated and said it was investigating how the error occurred.

Reports indicated that an earthquake of approximately magnitude 6.9 had struck near Russia’s Kamchatka Peninsula earlier that day. The Japanese warning system appears to have incorrectly processed the seismic information, generating an alert that was inconsistent with the actual event.

During a subsequent briefing, officials said there was no indication that a cyberattack on the agency’s servers had caused the incident. The initial assessment pointed to an erroneous system judgment, although the precise technical cause had not yet been established.

Why the Error Matters: Speed Must Be Balanced With Accuracy

Japan lies along the Pacific Ring of Fire and experiences frequent seismic activity. Its earthquake early-warning system is designed to provide as much advance notice as possible before strong shaking arrives, allowing people to take protective action and critical equipment to shut down safely.

Such systems must process seismic signals within seconds and estimate an earthquake’s location and magnitude using limited initial data. Early measurements can be uncertain, and estimates may need to be revised as additional observations become available.

Friday’s incident highlights a difficult challenge: when a system produces an extreme magnitude estimate and triggers a wide-area alert, authorities must rapidly identify anomalous data, correct inaccurate information and communicate the change clearly.

Repeated or inaccurate warnings can cause public anxiety and potentially weaken confidence in emergency alerts if similar incidents occur. At the same time, efforts to prevent false alarms must not undermine the speed needed to warn people about genuine earthquakes.

Investigation Under Way as Confidence in Warning Systems Comes Under Scrutiny

Japan’s Meteorological Agency said it would continue investigating the circumstances behind the erroneous warning. Key questions include how the unusually high magnitude estimate was generated, whether problems occurred during seismic-source identification or magnitude calculation, and how the alert passed through the system before being issued.

The incident does not mean that Japan’s earthquake warning system is generally unreliable, nor should it lead the public to disregard future emergency alerts. Residents should continue to follow official announcements from the Meteorological Agency and local authorities, check for updates when warnings change and take protective action as instructed.

Although the magnitude 9.9 alert was quickly withdrawn, the incident has renewed scrutiny of the accuracy and communication procedures of Japan’s earthquake early-warning system. Reducing the risk of false alarms while preserving the speed of emergency notifications will remain a critical challenge for authorities.