Creep and quakes on the northern transition zone of the San Andreas fault from GPS and InSAR data

Abstract

[1] The San Juan Bautista (SJB) segment forms the northern transition zone of the creeping section of the San Andreas fault. It is an area of moderate seismicity; the largest instrumentally-recorded earthquakes have been M5.5. However, historic records suggest six M ≥ 6 earthquakes occurred near the SJB segment between 1840 and 1899. It is also an area that has experienced several slow earthquakes. We perform a joint inversion of GPS and InSAR data to determine the current rate and distribution of interseismic creep. We find two low-slip/locked segments at mid-seismogenic depths that may represent source regions for the 19th century earthquakes. We find that the SJB segment is currently accumulating strain energy at the rate of one M6.3–6.7 earthquake per century. At this rate, the 1840–1899 sequence released 135–510 years of accumulated moment deficit.