Illuminating the physics of dynamic friction through laboratory earthquakes on thrust faults

Significance Our study explores a major challenge in earthquake science—the dynamics of thrust earthquake ruptures as they interact with the Earth’s surface, which is relevant to some of the most destructive earthquakes that have ever occurred. The work illustrates key features of the complex dynamic behavior associated with this interaction using an ultrahigh-speed imaging technique. The interaction leads to large and rapid reductions in normal stress. However, the frictional shear resistance does not decrease instantaneously with normal stress, as typically assumed, but experiences a significant delay. Such delay is important for a range of earthquake source problems that involve rapid normal stress variations.