Preface to the 1999 Chi-Chi, Taiwan, Earthquake Dedicated Issue

The 1999 Chi-Chi, Taiwan, earthquake ( M w 7.6) struck central western Taiwan at 1:47 a.m. local time (on 21 September or at UTC 17:47 20 September). The causal fault was immediately identified to be the mapped active Chelungpu thrust fault as it produced a remarkable 100-km-long surface break, with fault scarps as high as 8 m in places. The nucleation point of this long rupture was defined by an epicenter at 120.82 °E and 23.85 °N, with a focal depth of 8 km. A first-motion solution was reported to be striking N20 °E, dipping 30 °SE with an average rake of 85° (Chang et al., 2000). The event was officially named after the nearest town Chi-Chi by the Central Weather Bureau (CWB) (Shin, 2000). This was the most devastating earthquake to hit Taiwan in modern times. The Chi-Chi earthquake and its energetic aftershock sequence inflicted a casualty toll of 2435 and an estimated US$ 4 billion property loss (Tsai et al., this issue). This catastrophe was nonetheless fortunate in several aspects. The mainshock struck when schools were not in session; the loss of student lives would have been unthinkable in view of the total collapse of hundreds of school buildings. In emergency response, it was fortunate that the CWB completed in 1995 the Taiwan Rapid Earthquake Information Release System that was capable of electronically releasing pertinent information within a couple minutes of an earthquake occurrence. Rapid earthquake information greatly facilitated the disaster relief missions, and it mitigated further secondary losses. Scientifically, because of the completion of the Taiwan Strong-Motion Instrumentation Program (TSMIP), the occurrence of the Chi-Chi earthquake sequence has resulted in the richest seismological data recovery in the world to date, in both quality and quantity. These data were open to the world with a data CD of the …