HR: 1340h
AN: T43B-1337    [Abstracts]
TI: Shallow Seismic Reflection Images of the Active Chingshui and Tachia Faults in Central Taiwan
AU: * Jang, C
EM: sei9519@eq.ccu.edu.tw
AF: National Chung Cheng University, 168 University Rd., Minhsiung, Chiayi, TW 621, Taiwan
AU: Shih, R
EM: seirock@eq.ccu.edu.tw
AF: National Chung Cheng University, 168 University Rd., Minhsiung, Chiayi, TW 621, Taiwan
AU: Matsuta, N
AF: National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, TW 10617, Taiwan
AU: Lee, Y
AF: National Chung Cheng University, 168 University Rd., Minhsiung, Chiayi, TW 621, Taiwan
AB: Although there are many methods used for studying active faults, the seismic reflection method always plays an important role for imaging the fault and the subsurface structures. We could further correlate the shallow seismic data to the near surface geological condition, which is a key factor of forming a folding or faulting structure in an earthquake and resulting into different types of seismic hazard. In this paper, we will use shallow seismic reflection method to study an important fault system, Chingshui and Tachia faults in the deformation front area of western Taiwan. The Chingshui and Tachia faults are located at the western flank of the Tiehchanshan gas field in western Taiwan. Taiwan Petroleum Company has mapped the regional subsurface structure of the studying area by using many large-scale seismic lines. In the field, we may observe the vertical bedding of sandstone and conglomerate layers near the western front of the Tiehchenshan; however, the correlated faulting feature is not obvious according to the large-scale seismic data from the petroleum company at shallow depth. In other words, whether the observed geological features were related to a fault scarp or a folding scarp, or if the faults have been exposed to the surface was still not clear. The purpose of this study is to investigate that whether the near surface section of the two faults are actually blind or just not clearly observed in the regional large-scale seismic exploration data. A 48-channel seismic system was used in this study, a mini-impactor, JMS Mini65 was used as the source, and the data were collected with geophone arrays of three geophones. The preliminary result shows excellent quality of subsurface image. We will show the integrated interpretation of the seismic images with other results from geological survey, borehole logging, and geomorphic study.
DE: 7200 SEISMOLOGY
DE: 8010 Fractures and faults
DE: 8015 Local crustal structure
SC: Tectonophysics [T]
MN: 2007 Fall Meeting