Sat, Mar 10, 2012 - Page 2 News List

Weather bureau revises last month’s Wutai quake magnitude

UPWARD:The CWB changed the reading of the Feb. 26 quake to magnitude 6.4 from 6.1, while an aftershock of that earthquake was felt yesterday in Taimali Township

By Shelley Shan  /  Staff Reporter

The Central Weather Bureau (CWB) yesterday said it had raised the magnitude of a major earthquake that struck on Feb. 26 to 6.4 after seismologists gathered and analyzed additional data.

The bureau had initially reported the earthquake, with its epicenter in Wutai Township (霧台), Pingtung County, as magnitude 6.1.

Kuo Kai-wen (郭鎧紋), director of the bureau’s seismological center, said that adjusting the magnitude after an earthquake was normal.

“The detection system can deliver earthquake information right after an earthquake has occurred,” Kuo said. “However, adjustments may be necessary as we collect more information from observation centers and recalculate the magnitude.”

The bureau also reported a magnitude 4.3 earthquake — an aftershock of the Feb. 26 quake — yesterday morning. The epicenter was also in Wutai, which is about 29.4km northeast of the the county government building in Pingtung City. The depth of the earthquake was 12.9km.

The earthquake was most intense in Taimali Township (太麻里) in Taitung County.

On average, the nation sees three earthquakes exceeding magnitude 6.0 each year, the bureau said.

In 2010, an earthquake of the same magnitude as the Wutai quake last month occurred in then-Jiasian township (甲仙) in the former Kaohsiung county.

Tomorrow marks the one-year anniversary of an earthquake and tsunami that devastated northeast Japan, and experts in Japan warned that the magnitude 9.0 earthquake last year had caused the Philippine Sea Plate to sink further, which could trigger a magnitude 7.0 earthquake directly under Tokyo.

However, Kuo said this was not the first time experts in Japan have made such a prediction, adding that they had installed detection equipment around Tokyo Bay.

The epicenters of two strong earthquakes in Japan in the past two decades — the Great Hanshin earthquake in 1995 and last year’s earthquake — were not in Tokyo Bay.

Following the earthquake last year, Kuo said that the aftershocks mainly occurred along the North American and Pacific plates, adding that the Philippine Sea Plate has not changed substantially in terms of frequency of movement.

Kuo said there are plans to dig 70 observation wells to a depth of 300m at various locations around Taiwan, which could help the bureau monitor underground movements.

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