Least-squares inversion of spatial seismic refraction data

Abstract

A method is demonstrated for recording and inverting in-line and broadside seismic refraction and reflection data to obtain three-dimensional structure and velocity information. This technique of spatial seismic refraction recording produces a superabundance of common ray intersections at the target horizon. The full power of the linear least-squares inversion method may be used in the overconstrained case. A large number of recording instruments are required to perform the experiment efficiently but this has the advantage of reducing the number of sources and difficult source corrections. A damped least-squares inversion method has been found to give rapid convergence even in the case of complex faulted models using noisy data. The spatial seismic refraction recording method has been applied in a suboptimal experiment over the Williston Basin in southern Saskatchewan. The crustal structure consists of several normally faulted blocks defined by aeromagnetic anomalies over an area notable for its thick crust, local seismicity and a linear conductive anomaly.