How wide is the Calaveras fault zone—Evidence for distributed shear along a major fault in central California

High-angle and reverse faults offset Pleistocene and Holocene deposits across a zone several kilometres wide east of the Calaveras fault near Sunol, California. Alignment of recent epicenters with these and other fault traces suggests that a band of contemporary deformation roughly parallels the Calaveras fault. These exposures provide evidence that active deformation associated with this major transverse fault is distributed over a broad zone. This complex pattern of faulting suggests that other faults throughout central California may be more active than is recognized in seismic hazard assessments.