Kamchatka–Japan: JMA explains erroneous magnitude-9.9 warning
The agency reports an actual magnitude-6.9 earthquake near Kamchatka. Initial findings on the calculation error, with the investigation continuing.
What was added — 17.10.2026 · 07:13 Athens time
The reports do not establish a magnitude-9.9 earthquake. In two official reports dated 16 October 2026, the Japan Meteorological Agency (JMA) explains that its early-warning system overestimated the magnitude and incorrectly located the source in the Kuril Islands.
The earthquake and the incorrect estimate
The first report records an earthquake near Kamchatka at around 12:38 Japan time, with a preliminary magnitude of 6.9. Hakodate recorded intensity 1 on Japan’s seismic intensity scale — a different measure from earthquake magnitude.
At 12:40, a warning was issued for areas from Hokkaido to Chubu based on the 9.9 overestimate. ERT, citing AFP, reports that the erroneous alert was cancelled.
The second report’s findings
In its 17:30 Japan-time update, JMA says a magnitude formula intended for domestic earthquakes was applied to a very distant source. Different source estimates were also used for calculating magnitude and predicting intensity, although they should have matched.
The detailed investigation continues. These findings are not presented as a completed investigation or confirmation of full technical remediation. This is a review of the 16 October incident, not a new active warning.
Background — the 16 October EMSC and USGS records
A magnitude 6.9 earthquake struck Russia’s Kamchatka Peninsula on Friday 16 October 2026 at 6:35 a.m. Greek time — 03:35 UTC. The magnitude agrees in the latest records of the European-Mediterranean Seismological Centre (EMSC) and the US Geological Survey (USGS).
The latest measurements
EMSC places the focus at a depth of 130 kilometres and the epicentre about 146 kilometres south-southwest of Petropavlovsk-Kamchatsky. Its official page says the parameters have been reviewed by a seismologist.
USGS, also in a record marked as reviewed, gives a depth of 135 kilometres and an epicentre 76 kilometres northeast of Ozernovskiy. The services agree on magnitude, but their estimates of location and depth are not identical.
What was revised
Initial Reuters and ERT reports, citing EMSC, gave magnitude 7.0 and a depth of 140 kilometres. The centre’s subsequent record revised those figures to 6.9 and 130 kilometres; the initial estimate is not presented here as current.
The sources checked for this report do not establish a casualty or damage tally. That is not confirmation that there were no impacts. Seismological data alone do not constitute an official civil-protection warning.
English translation of the Greek edition · Read in Greek