Dynamic weakening and amorphization in serpentinite during laboratory earthquakes

作者：Brantut Nicolas^*; Passelegue Francois X; Deldicque Damien; Rouzaud Jean Noel; Schubnel Alexandre

来源：Geology, 2016, 44(8): 607-610.

DOI：10.1130/G37932.1

The mechanical properties of serpentinites are key factors in our understanding of the dynamics of earthquake ruptures in subduction zones, especially intermediate-depth earthquakes. Here, we performed shear rupture experiments on natural antigorite serpentinite, which showed that friction reaches near-zero values during spontaneous dynamic rupture propagation. Rapid coseismic slip (> 1 m/s), although it occurs over short distances (< 1 mm), induces significant overheating of microscale asperities along the sliding surface, sufficient to produce surface amorphization and likely some melting. Antigorite dehydration occurs in the fault walls, which leaves a partially amorphized material. The water generated potentially contributes to the production of a low-viscosity pressurized melt, explaining the near-zero dynamic friction levels observed in some events. The rapid and dramatic dynamic weakening in serpentinite might be a key process facilitating the propagation of earthquakes at intermediate depths in subduction zones.

• 出版日期2016-8