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進入《TAIPEI TIMES》 Hualien struck by earthquake swarm
Fallen masonry and sheet metal lie in front of a shop on Guangfu Street in Hualien City after an earthquake struck the region yesterday morning. Photo: Wang Chin-yi, Taipei Times
By Shelley Shan / Staff reporter
Hualien County was yesterday struck by more than 30 shallow earthquakes, with a few homes damaged, although there were no reports of injuries.
The earthquake swarm began with a magnitude 5.2 tremor at 6:52am, with the epicenter 5.1km southwest of Hualien County Hall at a depth of 5.9km. From 6:53am to 8:08pm, it was followed by 38 aftershocks of magnitude 3 to 5, Central Weather Bureau data showed.
Eighteen tremors occurred from 6:52am to 7:48am, the bureau said.
The quakes were at most 30km deep, putting them in the “very shallow” category, it said.
Residents reported hearing a loud subterranean rumbling.
In downtown Hualien, walls of some homes fell.
Seismology Center Director Chen Kuo-chang （陳國昌） said that the shaking was aftershocks from a series of earthquakes on Wednesday and Thursday last week.
The rapid succession of events yesterday was unusual, Chen said, adding that more aftershocks might occur over the next week.
Most of the aftershocks would be magnitude 3 to 4, with the largest possibly reaching magnitude 5, he said.
A magnitude 5.5 aftershock is unlikely, he said, citing the region’s seismic history.
Bureau data showed that four earthquakes of magnitude 5.5 or larger have occurred since 1973, when the agency started using more advanced seismometers.
A magnitude 6.5 quake occurred in 1990, the largest recorded in the area.
“Although earthquakes occur frequently in this region, people should not worry, as the risk of a large earthquake is low,” Chen said, adding that such low-level releases of energy accumulating in tectonic plates is a welcome sign.
Like the quakes last week, yesterday’s were caused by the collision between the Philippine Sea and Eurasian tectonic plates, with the oceanic plate subducting beneath the continental plate, Chen said.
The epicenters of yesterday’s quakes were between south of Jian Township （吉安） and north of Shoufong Township （壽豐）, Chen said, adding that the area is a north-south geologically fragmented zone that is tilted to the west.
The area’s quakes should have similar sequences, as they occur under similar conditions, he said.
As of yesterday, the bureau had recorded 22 earthquakes of at least magnitude 5 this year, close to the annual average of 23 to 25, Chen said, adding that 80 percent of them were detected in Hualien.
新聞來源：TAIPEI TIMES
