In situ seismic and electrical measurements of fracture anisotropy in the Lincolnshire Chalk

Abstract

Summary Using recently developed modifications of the conventional seismic refraction and electrical resistivity techniques, in situ measurements of P-wave velocity and resistivity anisotropy have been made at four sites in North Lincolnshire where the Chalk is overlain by a thin covering of drift. All sites showed significant velocity and resistivity anisotropy with the direction of the maximum observed velocity and resistivity being consistent with direct fracture observations made at two quarries within the area. It is suggested that such surface geophysical measurements can be very useful in predicting the predominant fracture direction in near-surface bedrock in which fractures are near vertical.