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Scientists forecast a large earthquake every 10 years

The interval between big earthquakes in Taiwan could be about a decade, if 10 recently discovered active faults in the south are taken into account, geologists at National Taiwan University (NTU) said yesterday.

After more than 2,400 lives were claimed by a 7.3 magnitude temblor in Taiwan on Sept. 21, 1999, Taiwanese geologists and seismologists began to review all active faults in a bid to find signs of when the next big earthquake might be.

By digging trenches along the Chelungpu Fault (車籠埔斷層), site of the disastrous 921 earthquake, Chen Wen-shan (陳文山), a NTU geosciences professor, has spent almost four years trying to discover the average period between the fault's dramatic movements.

"According to our studies, we conclude that the interval between the Chelungpu Fault's dramatic movements is between 350 and 400 years," Chen said yesterday at a press conference.

In other words, Chen said, Chelungpu could be regarded as one of the less threatening faults in Taiwan now, because accumulated energy has been released.

But Chen and his team discovered 10 faults in the plain between Chiayi and Kaohsiung.

Together with 42 active faults announced by the Central Geological Survey under the Ministry of Economic Affairs, Chen said, more than 50 active faults across Taiwan island might cause a devastating earthquake about every 10 years.

"Experiencing big earthquakes is the common destiny of people living in Taiwan, one of the most dangerous earthquake-prone areas in the world," Chen said.

Chen said the government should strongly support the survey on the activities of faults near urban areas and science parks and set up geology-related laws to regulate land use in areas near active faults.

Chen said that, at 1,600 people per square kilometer, Taiwan ranks eighth in the world in terms of population density.

"If we can't avoid using land near active faults, great casualties caused by earthquakes can be expected," Chen said.

Seventeen scientists are involved with the NT$30 million research, which is provided by the National Science Council and the Ministry of Economic Affairs.

Geologists yesterday reminded residents that the frequency of large earthquakes was unpredictable. Taiwan experienced earthquakes measuring more than 7 on the Richter scale in 1935, 1941, 1946 and 1951.

NTU scientists said people should be alert to the threats posed by earthquakes and strengthen the earthquake resistance of buildings.

"Western Taipei could be disastrously struck by a big earthquake if a nearby fault moves," said Chen Yue-gau (陳于高), also a NTU geosciences professor.

However, not everyone agreed with the scientists' conclusions.

Deputy Director General of the Central Weather Bureau Shin Tzay-chyn (辛在勤) said the number of active faults should not affect how residents view the risk of earthquakes.

He said people should be aware of the dangers earthquakes pose because, "after all, we can't avoid living in earthquake-prone areas."

The NTU scientists said that they would focus on faults in eastern Taiwan. The economics ministry's Central Geological Survey designated 25 faults that potential threaten to produce earthquakes.
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