5.2 earthquake jolts Okinawa; warning system fails


An earthquake with a preliminary magnitude of 5.2 jolted Miyako Island, Okinawa Prefecture, and its vicinity early Monday, the Meteorological Agency said.

There were no immediate reports of injuries or damage from the 2:32 a.m. quake, and no tsunami warning was issued. The quake measured 4 on the Japanese seismic intensity scale of 7 on several parts of the island, according to the agency.

The agency issued a quake intensity warning for the first time since its introduction last October. It predicted Monday’s quake would measure around lower 5 on the Japanese scale.

The warning system is designed to predict how strong the intensity of a quake may grow before the quake actually hits a region, and it is supposed to be activated when intensity is expected to be at a level of lower 5 or above.

On Monday, however, Miyako was hit by the quake five or six seconds after the preliminary tremor, while the intensity warning was issued some 10 seconds from the preliminary tremor, failing to alert the agency in time.

When a quake of lower 5 on the Japanese scale hit Ishikawa Prefecture in January, a warning was not issued because the system underestimated the intensity, predicting it would be at level 4.