Detection of a fault zone in the south of Bam using CSTMT method



Due to their inherent sensitivity to resistivity contrast, EM methods have an important role in detection of fault zones. In this paper, we experienced Controlled Source Tensor Magnetotelluric (CSTMT) method to recognize a fault zone in Bam area. An earthquake devastated the town of Bam on 26 December 2003. Surface displacements reveal that over 2 m of slip occurred at depth on a fault that had not previously been identified. This fault, located in south of Bam, is a strike slip fault which extends from the centre of Bam city southwards for about 12 km. Data were collected along a profile with an approximately NW-SE direction and perpendicular to the fault. The frequency range used in this method is in the range of 1-25 kHz. The CSTMT field measurements resolved well the resistivity contrast along the profile and 1D and 2D inversion models agree well with the data. Consequently, CSTMT is proved to be a useful method for detecting such structures, utilizing tensor data produced by two perpendicular magnetic loops together with a four electric sensor array.