Deformation of railroad tracks by slippage on the Hayward fault in the Niles District of Fremont, California*

Slippage (also called creep) on the Hayward fault has produced a right-lateral shift of about 0.7 feet in three sets of railroad tracks that were built 55 and 56 years ago. The average annual rate of 0.15 inch per year is about one-third the average rate of slippage on the San Andreas fault, but the rate has been much greater during short intervals. The zone of acute deformation of the tracks is 20 to 80 feet wide; the tracks are underlain by unconsolidated deposits more than 300 feet thick. Surface faulting at this locality in the 1868, and probably in the 1836, earthquake suggests that the processes of fault rupture and fault slippage can alternate at the same locality.