Static stress changes in magmatic pathways induced by subduction zone earthquakes: A parametric study on the influence of material heterogeneities and fault geometry

Large (M>8) subduction zone earthquakes induce stress changes across large distances and over short geological timescales. These stress changes can influence local or regional magmatic systems depending on many factors including distance from a hypocenter, fault geometry, the depth and orientation of magmatic conduit, rigidity contrast, and earthquake magnitude. The effect on volcanic systems is eventually translated into clamping or unclamping of magma chambers, dykes, and sills at different depths, leading in some cases to the triggering or suppressing of volcanic activity (Jenkins et al., 2021; Walters and Amelung, 2007). Previous works are generally based on Okada-type analytical solutions and use homogenous isotropic half-spaces to represent the subduction system. Here we use Finite Element (FE) models to explore how material heterogeneities and variable fault geometry (e.g. curved vs flat plane) contribute to stress changes imparted by large earthquakes with a focus on hypothetical conduits, dikes, and sills with a range of assumed orientations. To accurately represent the major mechanical components (e.g. slab and forearc) characterizing the subduction system we generated a finite element mesh using the FE mesher Cubit (coreform.com). Slip across the subduction interface is simulated using the FE solver Defmod (Ali et al., 2014; https://bitbucket.org/stali/defmod/). We run a series of forward models using both the heterogenous and homogenous configurations and search for differences in the clamping/unclamping patterns over different magmatic elements. Our investigation could have implications for a better understanding of earthquake-volcano interaction along major subduction systems such as the Cascadia subduction zone.