More than a month after the 921 earthquake, the National Science Council (NSC) has completed a detailed map of the Chelungpu fault (
Highly anticipated by building contractors, the map of the Chelungpu fault, which has been drawn to a 1:5,000 ratio, was produced by 21 academics who have been conducting field investigations since the earthquake.
At the time of the quake, the most precise fault maps available were those of a 1:100,000 ratio, while the official one available from the Central Geological Survey (CGS) was of a 1:500,000 ratio.
"The NSC's newly produced Chelungpu fault map will be useful in considering rebuilding plans because construction prohibition zones and restricted zones can be identified by referring to it," Huang Chi-yue (
Huang said it would be easy to tell how far the fault is from damaged structures if CPA officials are making administrative maps of townships along the Chelungpu fault using the same scale as that of the NSC map.
"However, to better identify permanent prohibited zones and restricted zones along the fault, geologists have been given a tougher job -- producing a map of the same fault with a 1:1,000 ratio. This more detailed map should be completed by Dec. 15," he said.
NSC director Huang Chen-tai (
The 1:1,000 map, he added, would present the recorded geologic characters of the fault and would become an excellent reference to other thrust faults in western Taiwan.
Huang said scientists had discussed how to produce a detailed overall fault map, which would be more precise than any fault maps currently in use.
One of the challenges for contractors during rebuilding will be understanding exactly where the fault line lies. The ability to pinpoint the exact location of the fault has become a contentious point between construction engineers and scientists.
Taiwan is creased with a number of fault lines and geologists have said that it is impractical, if not impossible to map out all sections of every fault line on the island. Moreover, they say that increasing the detail of maps from 1:100,000 -- the ratio used by geologists for making scientific surveys -- to 1:1,000 in an invitation for error.
Builders argue that the more detailed maps are necessary for making blueprints that have the degree of accuracy that they are familiar with.
The builders say that maps currently available do not have nearly enough detail to allow them to know with certainty if they are building the specified distance away from an active fault line.
Scientists say the priority should be producing an official fault map using a 1:25,000 ratio, a standard which has been adopted by the US, Japan and other countries.
"It's not realistic to produce precise fault maps at 1:1,000. For geologists, the difficulty is knowing exactly where the faults are, especially those deep underground," said Shih Ruey-chyuan (石瑞銓), a seismologist from National Chung Cheng University.
"Instead of relying solely on fault maps, builders should make comprehensive site inspections before they break ground on any structure," said Tsai Yi-ben (蔡義本), professor and dean of the College of Earth Sciences at National Central University.
According to one British scientist who worked in Taiwan after the quake, fault maps are an essential guide for builders.
"If detailed maps are not available at construction sites, engineers will have to deal more with local conditions," said Colin Taylor, a civil engineering professor from Bristol University.
He said that the fault maps are needed either for scientists to identify the sources and mechanism of major earthquakes or for engineers to use during construction.
Although the UK is relatively small, its geology has been studied for more than 150 years.
"The governmental British Geological Survey has produced quite detailed geological maps of the UK in various scales. The most detailed one is 1:1,000," Taylor said.
Another engineer, Dave Edge from the UK-based WS Atkins Group, an engineering consulting firm, stressed the need for accurate maps: "One cannot be sure that the law [prohibiting the building of houses closer than 15 meters from a fault line] is successful unless one knows actually where the fault lines are."
TECH EFFECT: While Chiayi County was the oldest region in the nation, Hsinchu county and city, home of the nation’s chip industry, were the youngest, the report showed Seven of the nation’s administrative regions, encompassing 57.2 percent of Taiwan’s townships and villages, became “super-aged societies” in June, the Ministry of the Interior said in its latest report. A region is considered super-aged if 20 percent of the population is aged 65 or older. The ministry report showed that Taiwan had 4,391,744 people aged 65 or older as of June, representing 18.76 percent of the total population and an increase of 1,024,425 people compared with August 2018. In June, the nation’s elderly dependency ratio was 27.3 senior citizens per 100 working-aged people, an increase of 7.39 people over August 2018, it said. That
‘UNITED FRONT’: The married couple allegedly produced talk show videos for platforms such as Facebook and YouTube to influence Taiwan’s politics A husband and wife affiliated with the China Unification Promotion Party (CUPP) were indicted yesterday for allegedly receiving NT$74 million (US$2.32 million) from China to make radio and digital media propaganda to promote the Chinese government’s political agenda and influence the outcome of Taiwan’s elections. Chang Meng-chung (張孟崇) and his wife, Hung Wen-ting (洪文婷), allegedly received a total of NT$74 million from China between 2021 and last year to promote candidates favored by Beijing, contravening the Anti-Infiltration Act (反滲透法) and election laws, the Chiayi District Prosecutors’ Office said. The couple acted as Beijing’s propaganda mouthpiece by disparaging Hong Kong democracy activists
EARLY ARRIVALS: The first sets of HIMARS purchased from the US arrived ahead of their scheduled delivery, with troops already training on the platforms, a source said The Ministry of National Defense (MND) yesterday said it spotted 35 Chinese military aircraft, including fighters and bombers, flying to the south of Taiwan proper on the way to exercises in the Pacific, a second consecutive day it has reported such activities. The Chinese Ministry of National Defense did not respond to a request for comment on the missions, reported just days before tomorrow’s US presidential election. The US is bound by law to provide Taiwan with the means to defend itself. Its arms sales to Taipei include a US$2 billion missile system announced last month. The MND said that from 9am yesterday,
A Control Yuan member yesterday said he would initiate an investigation into why the number of foreign nationals injured or killed in traffic incidents has nearly doubled in the past few years, and whether government agencies’ mechanisms were ineffective in ensuring road safety. Control Yuan member Yeh Ta-hua (葉大華) said in a news release that Taiwan has been described as a “living hell for pedestrians” and traffic safety has become an important national security issue. According to a National Audit Office report released last year, more than 780,000 foreign nationals were legally residing in Taiwan in 2019, which grew to more than
RSS