Testing a P-Wave Earthquake Early Warning System by Simulating the 1999 Chi-Chi, Taiwan, Mw 7.6 Earthquake

Abstract

The earthquake early warning (EEW) system is becoming a key practical tool for mitigating loss due to seismic events. Depending on the distance to the earthquake, it provides a few seconds’ to a few tens of seconds’ warning for people or automated facilities. Currently, many countries have an online operating or experimental EEW system, such as Japan (Nakamura 1988; Odaka et al. 2003; Horiuchi et al. 2005), Taiwan (Wu et al. 1998; Wu et al. 1999; Wu and Teng 2002; Hsiao et al. 2009; Hsiao et al. 2011), Mexico (Espinosa-Aranda et al. 1995; Espinosa-Aranda et al. 2009), the United States (Allen and Kanamori 2003; Wu et al. 2007; Allen et al. 2009; Bose, Hauksson, et al. 2009), Italy (Zollo et al. 2006; Zollo et al. 2009), Turkey (Alicik et al. 2011), Beijing (Peng et al. 2011), and Romania (Bose, Sokolov, and Wenzel 2009). Taiwan is situated at two converging plates, the Eurasian plate and the Philippine Sea plate. Located in this seismic active region, with a convergence rate of about 8 cm/year (Yu et al. 1997; Hsu et al. 2009), Taiwan has experienced many destructive earthquakes in the past century; the 1999 Chi-Chi earthquake is the largest such event. At that time, there was no real-time, online EEW system in Taiwan; however, a rapid reporting system had been operating since 1995 (Wu et al. 1997). Fortunately, during the 1999 Chi-Chi event the earthquake rapid reporting system had good estimates of hypocenter (23.87°N, 120.75°E, depth = 10 km) and magnitude ( ML = 7.3) and provided an intensity map in 102 seconds after the earthquake occurrence (Wu et al. 2000). The first EEW system in Taiwan was tested in 1998 in the Hualien area (Wu et al. …