Nonlinear seismology: the Priddis pump-probe experiment revisited

Kristopher A. Innanen, Gary F. Margrave, Malcolm B. Bertram

One of the objectives of the 2012 Priddis pulse-probe experiment was to revisit the idea of measuring nonlinear seismic responses on the exploration/monitoring scale. In this initial study, we consider the difference between seismic responses from (1) the CREWES mini vibe as a lone source carrying out a linear sweep, (2) a standard (Geokinetics Mertz 22) vibe as a lone source vibrating at a fixed 25Hz, and (3) the two simultaneously. We show examples of the uncorrelated data for these sweeps, as well as compare the sizes of the data sets with and without the background signal. Early indications are that “something is going on”, which we have not yet been able to falsify as nonlinear behaviour. Our main obstacle is to distinguish between true seismic nonlinearity and vibe feedback. We are unable at present to conclusively say what we have measured is one and not the other; pursuing these twin potential explanations for magnitude and phase differences is our near term plan.