Fault stability inferred from granite sliding experiments at hydrothermal conditions

Seismicity on crustal faults is concentrated in the depth interval 1–3 to 12–15km. Tse and Rice (1986) suggested that the lower bound on seismicity is due to a switch with increasing temperature from velocity weakening (destabilizing) to velocity strengthening (stabilizing) friction. They inferred this transition from friction data for dry granite; however, pore fluids exist at elevated temperatures throughout the crust, and may strongly influence strength and sliding behavior. We present new data from sliding experiments on granite at elevated T (23° to 600°) plus elevated PH₂O (100 MPa),