A study of fault plane mechanisms preceding the Thanksgiving Day, 1974 earthquake at Hollister, California

Fault plane solutions were obtained for 80 microearthquakes in a 900 square km area centered on the Busch fault during a one year period preceding the Thanksgiving Day, 1974 Hollister earthquake. Strike slip motion occurred in 65 of the quakes, mainly at active spots on the Sargent, Castro, Busch, and Calaveras faults. There are 11 thrust-type and 4 normal-type solutions. No discernable rotation of compressional axes was observed to precede the Thanksgiving Day earthquake.