Anomaly detection using surface waves

Summary We analyze compressional-wave seismic data to detect subsurface tunnels with emphasis on surface-wave propagation. Amplitude-envelope analysis is integrated into the backscatter analysis of surface waves (BASW) technique, increasing the robustness of the method. Domain sorting and 3D visualization provide a unique tool for dynamic interpretation of the seismic response to a lateral discontinuity. Modal separation, of fundamental and highermode energy, is presented and shown to create multiple coincident data sets that image an anomaly discretely. Our study suggests simple domain and instantaneous-amplitude transforms, combined with BASW techniques, can augment production-grade anomaly-detection investigations.