Back-propagating Ruptures in Fast and Slow Earthquakes

Back-propagating ruptures, characterized by a secondary front reversing into previously ruptured regions - such as boomerang earthquakes and rapid tremor reversals - have been recently documented due to advances in seismological techniques. While rupture complexity is often attributed to fault heterogeneity, its underlying physics remains unclear. I will present two studies on mechanisms of back propagation in fast and slow earthquakes, using analytical models and numerical simulations with rate-state friction. (1) Results demonstrate that back-propagating earthquakes can occur on frictionally homogeneous faults if ruptures propagate unilaterally, for example when faults are subject to stress gradients due to lateral loading. (2) I identify a mechanism for back propagation in slow slip events on rough faults and elucidate how frictional parameters influence velocities of forward and backward propagation. These findings provide new insights into the complex dynamics of fast and slow earthquakes and offer implications for improving seismic hazard assessment.

Speaker: Yudong Sun

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Room 350/372