9C seismic data acquisition for near-surface applications: recording, waveform reciprocity and 4C rotation

Multicomponent seismic data allow the study of shear (S) waves, which is of great interest to characterize, for example, anisotropy. We present a 9C seismic data analysis workflow that involves the acquisition of multicomponent seismic data using a sledgehammer striking a prismatic wedge as vectorial seismic source and 3C receivers. Inclined impacts on the two opposing sides of the wedge are rotated into a vertically- and horizontally-directed source. Advantages of this source are the simultaneous recording of horizontally- and vertically-directed sources with uniform coupling. Re-orienting the wedge allows acquiring data with orthogonally-oriented horizontally-directed sources. A 4C rotation of the two source and two receiver horizontal components allows then determining, for example, the apparent arrival direction of two orthogonally-polarized direct S-waves, which may differ from the source-receiver direction. While applied here to find the arrival direction of the direct S-wave, our workflow can also be used to study anisotropy through analysis of S-wave splitting.