An investigation of wind-induced and acoustic-induced ground motions

Wind noise at low frequency is a problem in seismic surveys, which reduces seismic image clarity. In order to find a solution for this problem, we investigated the driving pressure perturbations on the ground surface associated with wind-induced ground motions. The ground surface pressure and shear stress at the air–ground interface were used to predict the displacement amplitudes of the horizontal and vertical ground motions as a function of depth. The measurements were acquired at a site having a flat terrain and low seismic ambient noise under windy conditions. Multiple triaxial geophones were deployed at different depths to study the induced ground velocity as a function of depth. The measurements show that the wind excites horizontal components more than vertical component on the above ground geophone due to direct interaction with the geophone. For geophones buried flush with the ground surface and at various depths below the ground, the vertical components of the velocity are greater than the horizontal components. There is a very small decrease in velocity with depth. The results are compared to acoustic-ground coupling case. [This work is supported by USDA under award 58-6408-1-608.]