Di Toro Giulio, Hirose Takehiro, Nielsen Stefan, Pennacchioni Giorgio, Shimamoto Toshihiko
Dipartimento di Geologia, Paleontologia e Geofisica, Università di Padova, 35137, Padova, Italy.
Science. 2006 Feb 3;311(5761):647-9. doi: 10.1126/science.1121012.
Melt produced by friction during earthquakes may act either as a coseismic fault lubricant or as a viscous brake. Here we estimate the dynamic shear resistance (tau(f)) in the presence of friction-induced melts from both exhumed faults and high-velocity (1.28 meters per second) frictional experiments. Exhumed faults within granitoids (tonalites) indicate low tau(f) at 10 kilometers in depth. Friction experiments on tonalite samples show that tau(f) depends weakly on normal stress. Extrapolation of experimental data yields tau(f) values consistent with the field estimates and well below the Byerlee strength. We conclude that friction-induced melts can lubricate faults at intermediate crustal depths.
地震期间由摩擦产生的熔体既可以作为同震断层润滑剂，也可以作为粘性制动器。在这里，我们根据挖掘出的断层和高速（每秒1.28米）摩擦实验，估算了存在摩擦诱导熔体时的动态抗剪强度（τ(f)）。花岗岩类（英云闪长岩）中的挖掘出的断层表明，在10公里深处τ(f)较低。英云闪长岩样品的摩擦实验表明，τ(f)对法向应力的依赖性较弱。实验数据的外推得出的τ(f)值与现场估计一致，且远低于拜尔利强度。我们得出结论，摩擦诱导熔体可以润滑地壳中间深度的断层。
