From the Introduction

The technical abstracts presented at this workshop, convened in Sunol, California, on September 19, 2003 and associated field trip the following day, summarize some of the recent scientific knowledge gained along the Hayward Fault (e.g. Hart and others, 1982; Borchardt and others, 1992). The Hayward Fault and its northern extension, the Rodgers Creek Fault, are regarded as one of the most hazardous fault systems in the San Francisco Bay Area with a probability of about 27% for a ≥M6.7 earthquake over the next thirty years (Working Group on California Earthquake Probabilities, 1999; 2003).

Recent studies, some of which are described in the abstracts contained herein and summarized below, include advancements in creep measurements and geodesy, paleoseismology, relocation of the 1836 earthquake away from the Hayward Fault, modeling of the epicenter of the 1868 earthquake, geologic maps, modeling the depth of creep, double-difference relocated hypocenters, geometry and segmentation, understanding the relationship between the Hayward and Calaveras Faults, and estimates of earthquake probabilities. Historical seismicity data indicate that seismic activity along the Hayward Fault was much greater in the 19th century than in recent years (Bakun, this volume).

An analysis of intensity data for the M6.8 21 October 1868 earthquake suggests that most of the damaging ground motions were generated by slip located in the vicinity of San Leandro, possibly near a 1-km right step in the recent trace of the Hayward Fault (Bakun, this volume). A re-evaluation of the location of the 1836 earthquake, originally thought to be associated with the northern Hayward Fault, suggests that it occurred south of San Francisco Bay (Toppozada and Borchardt, 1998).