Digital Filtering Techniques for Interpreting Seismic Cone Data

Abstract

Seismic cone penetration testing (SCPT), a relatively new in situ technique, records the arrival of seismic waves generated at the surface using velocity or acceleration transducers installed in an electric piezocone. To distinguish the different seismic arrivals, instruments with fast response times are required, i.e., accelerometers. The fast response time of an accelerometer results in a very sensitive instrument with corresponding noisy time‐domain characteristics. One way to separate events is to apply digital filters, which characterize the signal frequencies and then isolate frequency spectrums of interest. The digital filter introduced in this paper is based on frequency‐domain filtering using cross‐correlation algorithms. The cross‐correlation filter concepts are synthesized by a computer program referred to as PS CrossCor, whose performance was evaluated by interpreting both synthetic and real data. Data from three sites is presented to compare the PS CrossCor and the established crossover method. The results from the analysis indicate that PS CrossCor is an accurate and reliable tool that greatly assists in determining seismic velocities, and has potential for determining other seismic parameters.