TOKYO, Oct. 16 (Xinhua) -- Japan's weather agency on Friday apologized for mistakenly issuing an early warning of a megaquake and strong seismic shaking around midday. The warning was canceled minutes later but temporarily disrupted train services in parts of the country.
The Japan Meteorological Agency (JMA) said the error was caused by its system misidentifying the epicenter and overestimating the temblor's magnitude as a catastrophic 9.9.
The agency said it is investigating the cause of the erroneous projection.
At around 12:40 p.m. local time, the JMA issued the alert for a wide area stretching from northern to central Japan, warning that strong shaking could occur in those parts. However, eight minutes later, it issued a follow-up notice canceling the warning.
The agency later confirmed that a 6.9-magnitude earthquake had struck Russia's Kamchatka Peninsula at a depth of about 160 km at around 12:38 p.m.
The early warning had forecast shaking of up to 7, the highest level on Japan's seismic intensity scale, but the strongest shaking actually recorded was an intensity of just 1, in Hakodate City, Hokkaido Prefecture, according to the JMA.
Public broadcaster NHK reported that the JMA's earthquake early warning system detects the faint tremors in the initial moments of an earthquake and automatically estimates its focus, magnitude, and seismic intensity using waveform data observed by seismographs near the epicenter.
When the system forecasts strong shaking of lower 5 or above on Japan's seismic intensity scale, it issues an earthquake early warning.
