Earth Planets Space, Vol. 58 (No. 1), pp. 5-21, 2006
Horng-Yue Chen, Shui-Beih Yu, Long-Chen Kuo, and Chi-Ching Liu
Institute of Earth Sciences, Academia Sinica, P.O. Box 1-55 Nankang, Taipei, Taiwan
(Received September 28, 2004; Revised September 2, 2005; Accepted September 2, 2005; Online published January 27, 2006)
The MW 6.5 Chengkung earthquake occurred in eastern Taiwan at 04:38 UTC on 10 December 2003. The GPS data from eighteen continuously recording stations (CORS) and 86 campaign-surveyed stations (CSS) collected 18 days to 9 months before and 6 days to 4 months after the main shock are utilized to analyze the coseismic and postseismic deformation associated with the Chengkung earthquake. The earthquake resulted from rupturing of the Chihshang fault, a 25-km-long segment of the Longitudinal Valley Fault (LVF). The coseismic horizontal displacements in the hanging wall showed a fan-shape distribution with vectors towards the west. On the other hand, the movements of the revealed a mirror fan-shape with relatively lesser amounts of displacement. The largest coseismic displacement, which reached 126 mm and 263 mm in the horizontal and vertical components, occurred near the epicenter area in the hanging wall. The largest postseismic displacements in 109 days, which approached 59 mm and 68 mm in the horizontal and vertical components, occurred near the surface trace of the Chihshang fault (TAPO) and near the epicenter area (CHEN), respectively. The stations near the Chihshang fault indicated a more significant postseismic displacement than coseismic one.
Key words: Coseismic displacement, postseismic deformation, Chengkung earthquake, Longitudinal Valley Fault.