Multi-phase Analysis of Surface Wave Survey Data for the Detailed Imaging of the Near Surface

High-resolution surface wave survey data often include distinct P-wave reflection, direct SV like reflection phase along with dominant surface waves. Then it is possible to apply not only conventional multichannel analysis of surface wave, but also usual P- and S-wave reflection data processing to the acquired data. To ensure whether observed S-wave like refection phase was SV-SV reflection or the converted one from P-waves, comparative measurements was conducted along the same line set on the soft ground. High-resolution SH-wave reflection surveying using Land Streamer was conducted. We adopted a compressed air hammer as a horizontal S-wave generating source. High-resolution surface wave survey was also conducted also using Land Streamer. Manual hitting of ground surface by means of a wooden hammer was employed as a vertical impulsive source. These data were processed through routine S-wave processing steps. As a result, the time sections were fundamentally the same as each other. In another case, a migrated depth section delineated a dipping bearing layer, and the depths of the layer were consistent with those directly identified by drilling and piling. In conclusion, when conducting surface wave survey densely comparable to the conventional seismic reflection surveying, multi-phase analysis is available to the data.