资源环境科技发展态势分析平台

Fault temperatures govern their weakening and control the dynamics of earthquakes during slip. Despite predictions of significant temperature rise within fault gouges during earthquake events, observations of frictional melting zones along exhumed faults are relatively rare. Could there be a heat transfer mechanism, previously not considered, that results in ubiquitously colder faults during earthquakes? We demonstrate that the remarkable, previously neglected mechanism of heat transfer through transient granular vortices may be at the core of this. We present and analyze results from perpetual simple shear experiments on a system of granular disks with which we are able to quantify the sizes and lifetimes of granular vortices within fault gouges during earthquakes. We then develop a formula that captures the contribution these vortices have on heat transfer. Using this formula, we show that crustal faults such as those in the San Andreas system may experience a maximum temperature rise 5 to 10 times lower than previously thought.