Near Field and Static Corrections of CSAMT Data Obtain in Volcanic and Geothermal Area Husnul Hamdi, Doddy Sutarno, Wahyu Srigutomo, Enjang Jaenal Mustopa
Insitut teknologi Bandung
Abstract
Controlled source audio-frequency magnetotellurics (CSAMT) is one of electromagnetic sounding method with frequency domain . CSAMT is a frequency-domain electromagnetic sounding technique which uses a fixed grounded dipole as an artificial signal source. Based on the measurement distance variation the transmitter with receiver on CSAMT, there are three zones, near field, transition, and far field. In the far field zone the plane wave assumption already admitted so that the equation for calculating the value of the resistivity can be applied together with the MT method using Cagniard equation. In the area of near field, source effects can still be captured directly by the receiver and the assumption of a plane wave can not be applied so that the data must be corrected. Correction data is also performed at the transition area. The static effects could result for two values of resistivity which can cause large errors in depth estimation and interpretation of the subsurface structure becomes complex. Static correction is done by averaging the resistivity curve in the measured region. Static correction can also be done by comparing the data obtained with the data TEM (Transient Electromagnetic)
