DISPLACEMENT ON THE SAN ANDREAS FAULT SUBSEQUENT TO THE 1966 PARKFIELD EARTHQUAKE BY STEWART W. SMITH AND MAX WYss

Immediately following the 1966 Parkfield earthquake a continuing program of fault displacement measurements was undertaken, and several types of instruments were installed in the fault zone to monitor ground motion. In the year subsequent to the earthquake a maximum of at least 20 cm of displacement occurred on a 30 km section of the San Andreas fault, which far exceeded the surfidal displacement at the time of the earthquake. The rate of displacement decreased logarithmically during this period in a manner similar to that of the decrease in aftershock activity. After the initial high rate of activity it could be seen that most of the displacement was occurring in 4-6 day epochs of rapid creep following local aftershocks. The variation of fault displacement along the surface trace was measured and shown to be consistent with a vertical fault surface 44 km long and 14 km deep, along which a shear stress of 2.4 bars was relieved.