Influence of grounded source geometry and terrain on the semi-airborne transient electromagnetic response from 3D simulation data

Abstract

The Semi-Airborne Transient Electromagnetic (SATEM) method utilizes a grounded source and airborne receivers, making it well-suited for high-precision, rapid, and deep electromagnetic surveying in complex terrain. Typically, the grounded source is assumed to be a simple linear form in existing inversions. However, in practice, the long grounded source can be bent or undulating due to the influence of terrain, resulting in significant deviations from the idealized straight-line model. Prior studies have investigated the effects of source bending in the horizontal plane or undulation in the vertical elevation separately. This paper provides a comprehensive analysis of the combined influence of complex terrain on the spatial deployment of the grounded source. Through a thorough examination of the superposition effects of multiple unfavorable factors, the study clarifies the spatio-temporal distribution of the complex source deployment pattern on the SATEM response. The findings provide a basis for confirming the reliability of inversion results and offer suggestions for improving field survey specifications for the SATEM method.