Fri, Jan 22, 2010 page2

• Study points to likelihood of 7.0 temblor in 50 years

  NO NEED TO PANIC A professor said that estimates on quake cycles are based on the hypothesis that temblors occur in a predictable fashion, which is hardly the case

  • By Shelley Shan / STAFF REPORTER
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  Following news of the devastating earthquake in Haiti, public attention has turned to the possibility of Taiwan being hit by a temblor of the same magnitude.

  The National Science Council said yesterday that the faults in Meishan (梅山) and Milun (米崙) have close to a 50 percent chance of a magnitude 7 earthquake occurring within 50 years.

  The fault in Meishan is located in Chiayi County, running from National Chung Cheng University to about 10km westward. The last earthquake on this fault was recorded on March 17, 1906, with the intensity topping 7.1 on the Richter scale, the council said.

  The fault in Milun is located in Hualien City. The last earthquake was recorded on Oct. 22, 1951, measuring 7.3 on the Richter scale, the council said.

  Council research showed scientists predicting that earthquakes of a similar intensity were likely to occur every 150 years in Meishan and every 125 years in Miluen.

  They also said there was a 45 percent chance that an earthquake of the same magnitude as in 1906 could occur within 50 years in Meishan, while there is a 42 percent chance that one could occur in Milun.

  Chen Yue-gau (陳于高), a professor at National Taiwan University’s geosciences department, told the press conference that the high possibility of earthquakes recurring was correlated to the estimated earthquake cycles.

  The cycles for both faults are relatively short — 150 and 125 years — compared with those of other faults, Chen said, adding that this in turn increases the possibility of imminent temblors.

  However, these estimated cycles were made based on the hypothesis that earthquakes occur in a predictable fashion, which is hardly the case, Chen said.

  “So far, we have not actually trenched those two specific faults and come up with more accurate data,” he said. “These possibilities were made by scientists when they trenched the locations near these faults.”

  Trenching of a fault is the most common technique used by geologists to investigate an active fault with surface rupture.

  Chen said the nation has 33 active faults, but only eight have data collected by different researchers.

  Among the eight faults, only two offer more valid data because of massive trenching work, Chen added.

  One is the Chelungpu fault (車籠埔斷層) — created after the earthquake on Sept. 21, 1999 — with an estimated earthquake cycle of 375 years. The other is the East Coast Fault System that connects the Yuli Fault (玉里斷層), the Chihshan Fault (池上斷層) and the Cimei Fault (奇美斷層), with an estimated earthquake cycle of 220 years.

  The statistics came to light at a press conference yesterday, when the council was supposed to brief the press about results of cross-departmental efforts to reduce disasters caused by earthquakes.

  NSC Deputy Minister Chen Cheng-hong (陳正宏) said the government was trying to shorten the time to send earthquake information from the Central Weather Bureau to the Central Emergency Operation Center.

  Chen Cheng-hong said that when a magnitude 6.9 earthquake shook Hualien on Dec. 19 last year, it took about 16 minutes for the data to get to the operations center.

  He said the council hoped the Legislative Yuan would approve a proposed geology law authorizing scientists to trench faults for research purposes.
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