Catastrophe modeling firm AIR Worldwide reports that a “magnitude 6.0 earthquake struck central Taiwan on March 27, 2013, at 10:03 a.m. local time (02:03:20 UTC). With its epicenter located at 23.840° North latitude and 121.135° East longitude, according to USGS, and a focal depth of 20.7 km, the event shook rural Nantou County (located about 250 km [156 miles] south of the capital of Taipei) and was felt throughout the island.”
AIR said “buildings swayed in Taipei for about 15 seconds, but building damage was confined to the Nantou region. Damage is expected to unreinforced masonry construction near the earthquake’s epicenter. In the population center closest to the epicenter (15 km [9.4 miles] from the epicenter), some building damage is expected, with the majority of damage largely limited to nonstructural elements such as glazing, cladding, suspended ceilings, and interior walls, as well as to contents. Well-engineered high-rise buildings should be unaffected by the earthquake.”
Dr. Bingming Shen-Tu, senior principal scientist at AIR Worldwide, commented: “Yesterday’s event occurred about 30-40 km east of the Chelungpu fault, the fault that generated the 1999 Chi-Chi earthquake. The location and fault mechanism indicate that the event occurred further down dip of the 1999 earthquake rupture to the east. It may have ruptured the deep part of the fault system that was responsible for the 1999 Chi-Chi earthquake.
“Building damage inflicted by the earthquake includes cracked exterior walls, fallen tiles, and broken windows. Contents damage has also been reported. Most damaged buildings are located in the Nantou, Changhua, and Taichung regions of central Taiwan.”
AIR also noted that although the temblor made buildings in the capital city of Taipei sway, “building damage in this city has not been reported. However, there have been reports that the earthquake gave rise to a fire in Taipei, but damage or disruption caused by this fire following event have not yet been reported at the time of this advisory.
“The temblor also caused disruption to transportation services; large boulders reportedly fell onto some roads in central Taiwan, and sections of high-speed rail line were temporarily shut down for inspection.”
Dr. Shen-Tu explained: “Due to its location, damaging earthquakes are not uncommon in Taiwan; for example, in 1999, the M7.6 Chi-Chi earthquake in central Taiwan caused property losses estimated at $11 billion. Taiwan is located in the collision zone between the Philippine Sea Plate and the Eurasian Plate.
“The most important tectonic features in Taiwan are the Longitudinal Valley Fault Zone (LVF) in eastern Taiwan and the Deformation Front Fault Zone (DFZ), a fold-thrust fault zone in western Taiwan. The DFZ is composed mainly of a series of active crustal faults along its central and northern segments. Thus, most historical earthquakes in central and northern Taiwan have been shallow.”
According to AIR the majority of low- to mid-rise buildings in Taiwan “are constructed with reinforced concrete frames and brick infill walls. Current Taiwan Building Codes (TBC) require ductile detailing of reinforced concrete frames, similar to the requirements of the American Concrete Institute and the Uniform Building Code (UBC) of 1982. Tall buildings are dominated by construction using reinforced concrete frames and shear walls.”
Source: AIR Worldwide