Modelling Non-Volcanic Tremor, Slow Slip Events and Large Earthquakes in the Guerrero Subduction Zone (Mexico) with Space-Variable Frictional Weakening and Creep

zigone, dimitri ; ben-zion, yehuda ; campillo, michel;

We explore with numerical simulations basic physical conditions leading to key observed features of non-volcanic tremor (NVT) in relation to slow slip events (SSEs) and earthquakes along the Guerrero segment of the Mexican subduction zone. To study the interactions between different modes of slip, and examine possible variations over timescales larger than the 15 year observational interval, we use a model with a planar interface governed by space-varying static/kinetic friction and dislocation creep in a 3-D elastic solid. A fault section with zero weakening during frictional slip fails in a mode corresponding to a ‘critical depinning transition’ that produces generically many observed features of NVT. A patch with elevated creep coefficients represents a section with SSE. Simulations with small added stress oscillations are used to examine triggering of NVT by large remote earthquakes. The results reproduce well the basic observed properties of NVT and SSE in the Guerrero area, while pointing to complex interactions between large earthquake cycles, quasi-period SSE and scale-invariant NVT behaviour. The model simulations provide additional information on expected frequency magnitude statistics, slip distributions and space–time properties of the different event types that may be tested with accumulation of future data. Some earthquake and NVT events near the opposite sides of the SSE patch have significant separation between their hypocentres and centroids. The rates of these events are correlated with the creep evolution in the SSE section. The results also suggest that aseismic deformation in the area may have transients on timescales larger than the observational period.