Asperity‐Driven Cascading Rupture of a Mw 1.6 Induced Microearthquake

Abstract Studies of small earthquake (M < 2) rupture processes traditionally rely on simplified models that assume symmetric slip or point sources. Using an exceptionally dense seismic network and empirical Green's function (EGF) analysis, we investigate the complex rupture of a Mw 1.6 microearthquake induced by hydraulic fracturing. Kinematic imaging via isochrone back‐projection resolves two distinct subevents occurring approximately 10 milliseconds apart, producing strong apparent rupture directivity. To test the physical mechanism driving this interaction, we perform dynamic rupture simulations constrained by these observations. We demonstrate that the failure of a primary asperity dynamically triggers a neighboring asperity via transient stress perturbations. This asperity‐driven cascading mechanism effectively explains the observed multi‐stage moment release and the apparent supershear rupture velocity (∼3.7 km/s). Our findings provide direct evidence that interacting fault asperities govern microseismic behavior. Such complexity challenges simple source assumptions and is essential for accurately assessing seismic hazards in human‐induced environments.