Taiwan is not likely to see a magnitude 9 earthquake or above, but it must be prepared for a magnitude 8 earthquake and an ensuing tsunami, the National Science Council (NSC) said yesterday.
Pointing to the historical data of earthquake reports in Taiwan between 1900 and 1999, NSC Deputy Minister Chen Cheng-hong (陳正宏) said: “We have yet to find an earthquake measuring above 7.5 on the Richter scale.”
“If we are to give a more conservative estimate, we think the largest earthquake would probably not exceed magnitude 8, but we cannot completely rule out that possibility either,” he said.
According to Chen, a magnitude 8 earthquake is most likely to occur off the nation’s northeast coast as a result of the Philippine Sea Plate moving north toward the edge of the Okinawa Trough.
He said the Taiwan Strait was very shallow, making it difficult to cause a continuous rupture zone when the sea plate moves toward it. This in turn would reduce the possibility of a strong earthquake, he said.
Nevertheless, Chen said that quake magnitude was not always proportional to the damage caused and urged the public to remain vigilant.
Chen said a tsunami was not likely to form on the nation’s east coast because the sea area was very deep.
While the tsunami induced by the massive earthquake in Japan on March 11 generated a wave height of 10m on Japan’s east coast, the wave height was reduced to 30cm by the time it reached Okinawa and 10cm when it reached Taiwan’s east coast.
“The southeast region is the most likely to be hit by a tsunami,” Chen said, adding that scientists could predict the impact of a tsunami in different places by using various simulations.
Meanwhile, Chen said the council has invited several researchers to study the Okinawa Trough and the Manila Trench to estimate the potential impact of a strong earthquake and tsunami on Taiwan. He said the results of their research could be released within three to six months.
Information collected through the research will be used by the nation’s disaster prevention and relief agencies, Chen added.
ADDITIONAL REPORTING BY STAFF WRITER