HR: 0800h
AN: T11D-1312    [Abstracts]
TI: Surficial Characteristics of the Chelungpu Fault System Revealed by LiDAR-derived Digital Elevation Model in west Central Taiwan
AU: * Huang, C
EM: b90204045@ntu.edu.tw
AF: Department of Geosciences, National Taiwan University, No.1, Sec. 4, Roosevelt Road, Taipei, 106 Taiwan
AU: Chan, Y
EM: yuchang@earth.sinica.edu.tw
AF: Institute of Earth Sciences, Academia Sinica, No.128, Sec. 2, Academia Road, Taipei, 115 Taiwan
AU: Hu, J
EM: jchu@ntu.edu.tw
AF: Department of Geosciences, National Taiwan University, No.1, Sec. 4, Roosevelt Road, Taipei, 106 Taiwan
AU: Lee, J
EM: jclee@earth.sinica.edu.tw
AF: Institute of Earth Sciences, Academia Sinica, No.128, Sec. 2, Academia Road, Taipei, 115 Taiwan
AU: Hsieh, M
EM: hsiehml@pchome.com.tw
AF: Department of Geosciences, National Taiwan University, No.1, Sec. 4, Roosevelt Road, Taipei, 106 Taiwan
AU: Chen, Y
EM: ygchen@ntu.edu.tw
AF: Department of Geosciences, National Taiwan University, No.1, Sec. 4, Roosevelt Road, Taipei, 106 Taiwan
AU: Shih, T
EM: tyshih@mail.nctu.edu.tw
AF: Department of Civil Engineering, National Chiao Tung University, No.1001, Ta Hsueh Road, Hsinchu, 300 Taiwan
AB: We applied post-earthquake airborne LiDAR-derived digital elevation model to characterize a complex segment of the Chi-Chi earthquake rupture area in west central Taiwan. It is demonstrated that geomorphic and structural features can be more reliably delineated using the high-resolution LiDAR-derived DEM, especially the advantage applying its high vertical resolution of about 10-15 cm. First, the Chelungpu fault system includes two subparallel fault traces in the study area. The deformed footwall terraces show gentle folds trending about NNE in the north and about NE in the south. Second, creek profiles indicate that slope changes usually associated with the Chi-Chi earthquake rupture, fault scarps, and folded terraces. Third, the LiDAR DEM shows the Fengyuan city is situated on a gently folded terrace with a NE-trending fold axis. The LiDAR DEM also reveals well-defined paleo-channels and river-incision scarps within the populated Fengyuan city. The gradually shifted paleo-channels suggest that the Dachia river had migrated from southwest towards west to its present direction. To the east of the Fengyuan city, the Chi-Chi earthquake scarp was uplifted about 3 $\sim$ 7 meters during the coseismic event. However, the LiDAR DEM indicates that the scarp offset is more than 3 $\sim$ 7 meters and up to 10 meters. The height difference supports at least one rupture event had occurred prior to the Chi-Chi earthquake along his young fault scarp. We also compared 1:1000 scale pre-earthquake city planning map with the post-earthquake LiDAR DEM to better determine coseismic displacement on the hanging wall. In total, the presented surficial observations indicate the region to be tectonically active in the past and are consistent with the continual NW movement of the Chelungpu fault.
DE: 7221 Paleoseismology
DE: 7223 Seismic hazard assessment and prediction
DE: 7230 Seismicity and seismotectonics
DE: 8107 Continental neotectonics
DE: 1200 GEODESY AND GRAVITY
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting