| dc.description.abstract | Taoyuan, Hsinchu, and Taipei are three major metro areas in northern Taiwan. This study attempts to survey the resistivity structures and locations of the three active faults – Hukou Fault, Hsinchen Fault, and Sanchiao Fault – passing through the three metro areas and has thus provided 23 resistivity imager profilings (RIP), 39 vertical electrical soundings (VES), and 50 audio-frequency magnetotellurics method (AMT) for this purpose.
This study has examined the relationships between faults and profilings in addition to the underground resistivity and has acquired following results accordingly:
1. Both Hukou Fault and Hsincchen Fault are thrust faults wherein the hanging walls are lowly resistivity and fault footwall are highly resistivity. Discontinuous geoelectrical or lateral rapid change resistivity is shown in electrical layers, especially in the fault trace or fault zone. Anomalous bands in a homogenous layer are one of the features shown in the Hsinchen fault. In addition to a large lateral resistivity contrast shown in the Sanchiao fault, the contacts surface is very rough.
2. The advantage of RIP result has a better stability, higher resolution and less time-consuming than other resistivity sounding methods. But in the study area, surface obstacles limited the spread of some survey lines, thus the targeted depth of investigation was unattained. AMT survey can be interfered by culture EM wave; the quality of its sounding results is always severely affected, especially in the Taipei area. However, combining the AMT sounding results with the gravity result, geologic data, and formal logging information, the Sanchiao fault and the boundary between the sediment and basement of Taipei Basin can be recognized.
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