Viscous roots of active seismogenic faults revealed by geologic slip rate variations

The flow of ductile rocks in the deep crust and uppermost mantle is thought to add stress to faults in the shallow crust, potentially bringing the faults closer to rupture. Measurements of fault offsets in the Italian Apennines show that earthquake recurrence is largely controlled by viscous flow of deeper rocks in localized zones. Viscous flow in the deep crust and uppermost mantle can contribute to the accumulation of strain along seismogenic...