Focal mechanism studies in the New Madrid seismic zone

Abstract

abstractA recent study of seismicity in the New Madrid seismic zone by Stauder et al. (1976) has shown the existence of linear micro-earthquake patterns of up to 120 km in length. This study presents the results of composite microearthquake focal mechanism studies along these trends together with focal mechanisms obtained using long-period surface-wave data from larger events. Due to the present microearthquake array geometry, the composite focal mechanism studies do not indicate a complete picture of the nature of the earthquake processes for all the trends. However, the motion on the major 120-km long trend into northeastern Arkansas has significant components of right lateral fault motion. The consistency of surface-wave focal mechanisms and the composite focal mechanism along this trend indicates that it should be considered as a single tectonic unit.