HR: 0800h
AN: T51C-0691    [Abstracts]
TI: A STUDY OF ELECTRICAL STRUCTURES OF SHANCHIAO FAULT IN TAIWAN USING AUDIO-FREQUENCY MAGNETOTELLURIC (AMT) METHOD
AU: * Yang, C
EM: yang@cyu.edu.tw
AF: Chieh-Hou Yang, 229, chien-Hsin Rd., Jung-Li, 320, Taiwan
AU: Liu, H
EM: lhchang@cyu.edu.tw
AF: Chieh-Hou Yang, 229, chien-Hsin Rd., Jung-Li, 320, Taiwan
AB: The Shanchiao normal fault is located in the western edge of Taipei basin in an N-E to S-W direction. Since the fault crosses through the Tertiary basement of Taipei basin, it is classified as an active fault. The overburden of the fault is sediments with a thickness around few tenth meters to several hundred meters. No detailed studies related to the Shanchiao fault in the western side of Taipei Basin are reported. In addition, there are no outcrops which have been found on the surface. This part of fault seems to be a potential source of disaster for the development of western Taipei basin. The audio-frequency magnetotelluric (AMT) method is a technique used to find the vertical resistivity distribution of formation and to characterize a fault structure through the ground surface based measurement. Based on the geological investigation and lithogic information from wells, the AMT data from six soundings at Wugu site, nine soundings at XinZhuang site and eight sounding at GuanDu site were collected on a NE-SW profile, approximately perpendicular to the prospective strike of the Shanchiao fault. AMT data were then inverted for two- dimension resistivity models (sections). The features of all resistivity sections are similar; an apparent drop in resistivity was observed at the position correlates to the western edge of Taipei basin. The predicted location of Shanchiao fault matches was verified by the lithologic sections of boreholes nearby. It indicates that the Shanchiao normal fault may associate with the subsidence of Taipei basin. The basement is clearly detected as a geoelectrical unit having resistivity less than 250 . It has a trend of increasing its depth toward S-E. The uplift of layers in the east of resistivity sections may affect by the XinZhuang thrust fault from the east. As with each site, the calculated resistivity may affect by cultural interference. However, the AMT survey still successfully delineates the positions and features of the Shanchiao fault and western edge of Taipei basin. Keywords¡GCSAMT, RIP, Shanchiao fault
DE: 0925 Magnetic and electrical methods (5109)
DE: 5109 Magnetic and electrical properties (0925)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting