Connection between Milun Fault, earthquake unclear: research

2018/02/12 20:16:37 fontsize-small fontsize-default fontsize-big
CNA file photo

CNA file photo

Taipei, Feb. 12 (CNA) An initial study into a possible link between the magnitude 6.0 earthquake that struck Hualien in eastern Taiwan last week and a fault line in the area has not reached a concrete conclusion, according to the Central Geological Survey (CGS) under the Ministry of Economic Affairs.

There is no evidence that the Milun Fault was to blame for the earthquake, said CGS Deputy Director Tsao Shuh-jong (曹恕中) after a CGS team wrapped up its initial investigation.

The pattern of broken ground surface and soil liquefaction indicates, however, that the earthquake caused displacement along the 7.2-kilometer fault, Tsao said.

He pointed out there was a vast area of broken ground within a 300-meter range of the fault line, which runs southwest from the Qixingtan shoreline to the west side of Meilun Mountain, turns south-southeast under downtown Hualien, and descends south of Hualien City.

That area is geologically sensitive, which is why many buildings on it reported severe damage, Tsao said.

Details about the interaction between the earthquake and the fault have to undergo further examination, he said.

A final report will be available by the end of March, Tsao said, adding that it will be used to re-adjust areas of high seismic hazard in Hualien for better planning.

While several experts, including Tsao, indicated before the report was released, that the fault could be the reason for the earthquake, a former head of the Central Weather Bureau espoused a more conservative view.

Shin Tzay-chyn (辛在勤) pointed out that the last time activity was recorded on the Milun Fault was in 1986, and resulted in a magnitude 6.2 earthquake.

It is unlikely that a fault would become active after only around 30 years, according to Shin.

Whatever the cause, the pattern of the Hualien earthquake was "unprecedented," said Chen Kuo-chang (陳國昌), acting director of the bureau's Seismology Center.

"This is unprecedented and not a normal release of energy," he said, explaining that both the intensity and number of foreshocks and aftershocks are higher than have ever been recorded in the region.

(By Huang Ya-chuan and Lee Hsin-Yin)

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