[S-CG45] Science of slow-to-fast earthquakes

[SCG45-22] Simulated earthquake cycles in temporally varying fault damage zones

*Yihe Huang¹、Prithvi Thakur²、Peng Zhai¹ (1.University of Michigan Ann Arbor、2.Karen Clark and Co.)

キーワード：earthquake, fault damage zone, coseismic damage, interseismic healing, precursory velocity change

Faults are usually surrounded by damage zones, whose material properties change before and after earthquakes. Here we use fully dynamic earthquake cycle simulations to characterize the behaviors of earthquakes in fault damage zones. We show that immature fault zones promote small subsurface earthquakes with irregular recurrence intervals, whereas mature fault zones host pulse-like earthquake rupture that can propagate to the surface, extend throughout the seismogenic zone, and occur at regular intervals. The coseismic damage and interseismic healing in immature fault zones play a key role in allowing the development of slow-slip events and fault creep, which can propagate into the seismogenic zone and thus limit the sizes of subsequent earthquakes. Using earthquake cycle simulations, we also address how the precursory changes of seismic wave velocities in fault damage zones can affect the nucleation processes and recurrence intervals of earthquakes. The results demonstrate that the nucleation size of earthquakes can be significantly reduced due to a small amount of precursory velocity change, which can then turn small earthquakes and slow-slip events into large earthquakes and cause earlier nucleation of earthquakes over earthquake cycle.