A magnitude 6.1 earthquake with its epicenter in Wutai Township (霧台), Pingtung County, shook southern Taiwan yesterday at 10:35am, the Central Weather Bureau said.
It was the largest land quake to hit the nation in two years, the bureau said, after a magnitude 6.4 earthquake hit then-Jiasian Township (甲仙) in the former Kaohsiung county in March 2010. A submarine earthquake of magnitude 6.1 occurred off the coast of Hualien in November 2010.
Though no casualties were reported as of press time, terrified residents in the south rushed out of their homes, while products fell from shelves in shops in Greater Tainan.
Railway traffic was also disrupted. Two high-speed trains were forced to temporarily stop near the Tainan high-speed rail station. Two southbound trains were canceled, further delaying hundreds of travelers, and the Kaohsiung MRT system also suspended operations.
Two aftershocks — magnitude 4.0 and 4.2 — followed the main earthquake within eight minutes. The epicenters of the aftershocks were in Jinfong Township (金峰) and Beinan Township (卑南), Taitung County.
A third aftershock of magnitude 4.1 with its epicenter also in Beinan was recorded at 4:25pm. As of 5pm yesterday, 67 unfelt aftershocks had been recorded, the bureau added.
The bureau said the main earthquake, of which the epicenter in Wutai Township is 30.4km northeast of Pingtung City, occurred at a depth of approximately 20km, which the bureau categorized as “very shallow.”
A very shallow earthquake is defined as one that occurs at no more than 30km beneath the ground.
Seismological Center director Kuo Kai-wen (郭鎧紋) said yesterday’s earthquake was caused by the extrusion of the Eurasian Plate and Philippine Sea Plate.
“The epicenter was close to the border of Pingtung County and Taitung County, which is at the southern end of the Central Mountain Range, a relatively newer geological stratification,” Kuo said. “Rather than moving under the Eurasian Plate, the Philippine Sea Plate mounted on the Eurasian Plate this time.”
The earthquake caused the East Coast Mountain Range — between the Central Mountain Range and the rift valley from Hualien to Taitung — to move further west, forcing the Central Mountain Range to rise higher, he added.
The earthquake registered an intensity of five on the bureau’s five-point scale, and was felt in Taitung County’s Chulu (初鹿); Sandimen Township (三地門), Pingtung County; Sinhua District (新化), Greater Tainan; and the urban core of Greater Tainan.
Taitung City, Greater Kaohsiung, Chiayi City, Pingtung City and three other locations registered an intensity of four.
The bureau’s stations in Hongye Village (紅葉), Hualien County; Ershuei Township (二水), Changhua County; Mingjian Township (名間), Nantou County; and Magong City (馬公), Penghu County, reported an intensity of three.
An intensity level of two was measured in Nantou City, Hualien City, Yilan City, Hsinchu City, Taipei City’s Xinyi District (信義), Liyutan (鯉魚潭) in Miaoli County, as well as throughout Greater Taichung.
The rest of Taipei City registered an intensity of one.
On average, the nation sees three earthquakes exceeding magnitude 6.0 each year.