Analysis on Deep-Well Apparent Resistivity Measurement at Dabaishe Seismic Station

Abstract

Abstract We interpret the horizontally layered homogeneous medium model of Dabaishe station according to the electric sounding data. The measurement array at the station is the fixed Schlumberger arrays. The deep-well measurement has two set of arrays. One is horizontally placed under 100 meters, and the other is vertically arranged. Under the layered model, we analyze the sensitivity coefficient variations of deep-well apparent resistivity measurement versus the different electrode depth and the spacing of current electrodes. The results show that the horizontal deep-well measurement has well ability on inhibiting disturbances from surface. However, its current electrodes spacing is relatively short, only 60 meters, thus the measurement data cannot effectively reflect the resistivity variations from deep mediums. Electrodes of the vertical deep-well measurement array locate within the layer where underground water level changes. Therefore, its measurement data suffers great affection from the water level variations and it is very difficult to distinguish the resistivity variations of deep mediums from the data. In order to better detect information associated with earthquakes, the spacing of horizontal arrays of AB/2 should be set as 250-350m, and the bury depth exceeds 150m. A Horizontal array along NS direction is also recommended.