Seismic prism waves generated by seafloor canyons and their effects on subsurface imaging

Abstract

Complex seafloor bathymetry can create significant challenges for subsurface imaging and geologic interpretation of seismic exploration and monitoring data. Steep seafloor canyons that cut through continental shelf areas can produce very strong seismic wavefield distortions. Neglecting such wavefield complexity can result in inaccurate velocity models, significant imaging errors, misleading amplitudes and uncertain geologic interpretations. In this paper we investigate the kinematic and dynamic effects of seismic 'prism waves' generated by seafloor canyons. Prism waves are waves that undergo multiple primary reflections at scattering interfaces before propagating to the recording sensor array. We demonstrate that strong prism waves can be generated for realistic seafloor canyon geometries, and show how their adverse effects can contaminate the seismic imaging process.