Pattern of faulting and nature of fault movement in the San Fernando earthquake

Abstract

In an effort to understand the mechanism of the February 9, 1971, San Fernando earthquake in relation to seismic observations and regional geology, we have gathered information on the occurrence and amount of ground displacement by surface faulting. Most of the field data were obtained within the first 4 days after the earthquake, because we wished to describe the fault features as much as possible in their pristine state. Systematic observations were made only in the area generally east of Sylmar and Olive View Hospital, that is, in the eastern part of the area strongly affected by the earthquake, where manifestations of surface faulting were particularly well developed. While our description of faulting is therefore limited to this area and while there doubtless are fault features that we have missed in the area studied, our results are presented here as a contribution to the general body of knowledge about the earthquake.