Introduction to the Special Issue on Paleoseismology of the San Andreas Fault System

Abstract

The purpose of this special issue of BSSA is to provide a state-of-the-science compendium of data on the rupture history of the San Andreas fault from recent paleoseismic investigations. The San Andreas fault is the primary boundary fault between the Pacific and North American plates and one of the most thoroughly studied faults in the world. Fourteen articles prepared by 74 authors provide dates of surface ruptures and/or measurements of slip or slip rate at 10 paleoseismic investigation sites along the main trace of the San Andreas fault, at one site on the Hayward fault, and along the northern San Jacinto fault. This issue includes documentation of the longest multicycle earthquake sequence in California—and possibly in North America (14 ruptures at the Wrightwood site). Geographic coverage extends almost along the entire San Andreas fault system, from Bodega Bay in northern California to the Mecca Hills in the Coachella Valley. The issue also includes articles linking paleoseismic data with modern instrumental recordings of ground motion and seismicity. Data on the earthquake history of the San Andreas fault form the basis of numerous models of fault behavior and calculations of seismic hazard. Despite the relatively large amount of data available for the San Andreas fault, there remain unresolved questions about segmentation, the rupture patterns of large earthquakes, and characteristics of earthquake recurrence. The data presented in this special issue contribute toward understanding the spatial and temporal rupture history of the San Andreas fault over multiple rupture cycles during the last few hundred to few thousand years. This is the timescale of greatest interest for seismic hazard assessments and fault modeling. This introduction provides an overview of the issue and summarizes results in simplified, tabular form. Table 1 contains dates of surface ruptures and/or average recurrence intervals reported from 10 sites discussed in …