3D Modeling of Long‐Term Slow Slip Events Along the Flat‐Slab Segment in the Guerrero Seismic Gap, Mexico

During the last two decades, quasi‐periodic long‐term slow slip events (SSEs) of magnitude up to Mw7.5 have been observed about every 4 years in the Guerrero Seismic Gap, Mexico. We present numerical simulations of the long‐term SSE cycles along the 3D slab geometry of central Mexico. Our model accounts for the hydrated oceanic crust in the framework of rate‐and‐state friction and captures the major source characteristics of the long‐term SSEs occurring between 2001 and 2014, as inferred from geodetic observations. Synthetic surface deformation calculated from simulated fault slip is in good agreement with the cumulative GPS displacements. Our results suggest that the flat‐slab segment of the Cocos plate aids the large magnitudes and long recurrence interval of the long‐term SSEs. We conclude that 3D slab geometry is an important factor in improving our understanding of the physics of slow slip events. Plain Language Summary Slow slip events (so‐called “silent earthquakes”) have been detected worldwide in circum‐Pacific subduction zones, such as Cascadia and southwest Japan. Long‐term slow slip events occur about every 4 years in the Guerrero Seismic Gap (Mexico) where tectonic plate movement is largely accommodated by aseismic slip and no large earthquakes have been observed since 1911. We build a numerical model incorporating a realistic 3D geometry of the subducting slab and lab‐derived friction laws to investigate the physics of these slow slip events. The simulated events have slip patterns, magnitudes, and recurrence intervals comparable with the observed ones. Our study demonstrates that plate geometry is an important factor to account for when studying the initiation, propagation and arrest of slow slip. Key Points We model sequences of long‐term slow slip events in the Guerrero Seismic Gap using a geometrically flexible three‐dimensional (3D) boundary integral method Our model reproduces the source characteristics and surface deformation of the four long‐term slow slip events (SSEs) inferred from geodetic observations The flat segment of the Cocos plate likely aids the large magnitudes and long recurrence interval of the slow slip events in Guerrero