Subsurface velocity model in post-glacial deposits based on multichannel analysis of surface waves

First introduced and developed in the 1990s, the multichannel analysis of surface waves (MASW) is one of the active, seismic methods created for shallow seismic imaging. Surface waves generated from a sledge hammer were used for delineation of subsurface structures. MASW is analyzing the propagation velocities for each component of surface waves by generating the dispersion curves, and then as a result produces shear-wave velocity (Vs) profiles below the surveyed surface. A Vs distribution in the depth domain is obtained in 1-D or 2-D variant after a quite simple inversion procedure. Shear-wave velocity iVs) is one of the elastic constants, closely related to changes in geology. Weathering zone in post-glacial area, as one of the most complex geological forms, were chosen to check MASW ability to evaluation near-surface, folded structures. Data were acquired for typical MASW continuous profiling schema in 2 meters intervals and performed using land-streamer at the distance of about 200 m, along previously existed reflection seismic line. The analysis was supported by records from previously made reflection seismic investigations. Image of glacial till on MASW 2-D map is characterized by appearance of mix clay-sandy layers, folded and locally discontinued. Furthermore, the most of detected middle layers from 0 m up to 30 m deep form pile of thrust slices. Application of obtained subsurface model could be considered at a two main stages. First of them has a geological background where continuous Vs distribution supporting geological and geomorphological works. The second one is connecting with prospecting seismic where 2-D Vs map could be used for static purposes.