资源环境科技发展态势分析平台

Earthquakes are dynamic rupture events that initiate, propagate, and terminate on faults within the Earth's crust. Understanding rupture termination is essential for accurately estimating the maximum magnitude earthquake a region might experience. We study termination on sequences of M - 2.5 earthquakes that rupture a 3-m granite laboratory sample. At this large scale, nucleation, propagation, and termination are either completely or partially confined within the sample-unique observations for experiments on rock. We compare measured termination locations to estimates from a fracture mechanics-based model to quantify the fracture energy of the laboratory earthquakes, which compare well with estimates from small natural quakes. Our results provide a mathematical framework that links micrometer-scale friction parameters to meter-scale earthquake mechanics, shows that a 3-m slab of granite can behave similar to a 200-mm sheet of glassy polymer, and demonstrates how small events can prime a fault for larger, damaging ones.

Plain Language Summary We have built a machine that squeezes a 3-m long slab of granite to generate sequences of slip events that spontaneously rupture a precut planar fault within the rock, similar to how earthquakes rupture faults within the Earth. While slip events generated on most rock mechanics machines rupture through the entire sample, the slip events we generate at this large scale are more realistic of natural earthquakes because rupture often stops after propagating only part-way down the rock sample. We describe a model that allows us to quantify where and why a rupture stops as a function of the stress distribution on the fault and friction properties. By matching the model to the experiment we estimate the fault's fracture energy. The model can also be used to show how small earthquakes can prepare a fault for a larger one.