Seismic acquisition and processing of onshore dual fields by a reciprocal experiment

We present the analysis of seismic wavefields acquired by dual sensors during an onshore reciprocal experiment. The method of separating upgoing and downgoing waves in signals recorded by dual pressure (hydrophone) and particle-velocity (geophone) transducers is well known, and commonly used to improve marine seismic data. A similar application is more difficult onshore, where pressure transducers are typically not available at surface. Nevertheless, the advantage of using dual recordings has aspects of potential interest for near-surface signal analysis. In this work, we study the signals recorded by surface geophones and an assembly of acceleration and stress sensors buried at shallow depth in a fixed position. The field data are obtained by reciprocal geometry with respect to that of a conventional shot, by moving a surface seismic source at different offsets from the receiver location. The analysis shows that combining the signals obtained at the fixed recording position separates first arrivals (direct and refracted) and surface-waves propagating along the seismic line.