Imaging shallow fault structures by three-dimensional reverse time migration of ground penetration radar data

Abstract

Ground penetrating radar (GPR) is an effective technology for investigating shallow underground structures using high-frequency electromagnetic waves. Migration is necessary to interpret GPR data because it resolves the true structure from distorted and blurry time-domain profiles. Wave-equation-based reverse time migration (RTM) can provide higher-resolution and more reliable results compared to ray-based migration methods. We have developed a three-dimensional RTM approach based on the finite-difference time-domain algorithm and applied it to field GPR data collected in the northern segment of the Huangzhuang-Gaoliying fault in suburban Beijing. Migrated images clearly show the subsurface structures, with clear indications of underground reflectors in agreement with geological cross-sections proposed in previous studies. Our results demonstrate that GPR is a convenient, non-destructive, and reliable technique that provides a new comprehensive approach to image subsurface conditions, thus allowing effective monitoring of active faults in urban areas.