Three-dimensional model of the Mono Basin (California): finite element analysis of the interaction between the Hartley Spring Fault and the Mono Dike

Mono Basin is a northward-trending structural depression lying immediately east of the central Sierra Nevada (California) that extends from the northern edge of Long Valley Caldera towards the center of Mono Lake. The Mono-Inyo Craters volcanic chain forms a prominent 17-km-long arcuate ridge within the Mono Basin. Recent studies have proposed that the volcanism and tectonism in this area is likely interrelated. Stratigraphic data suggest that a series of strong earthquakes occurred during the North Mono-Inyo eruption sequence of 1350 A.D. Geological data are consistent with rupture of the Hartley Springs fault during the eruption sequence. The temporal proximity of these events suggests the possibility of a causal relationship. We use the Finite Element Method (FEM) to generate a three-dimensional model of the Mono Basin and investigate the feedback mechanism between dike intrusion and slip along the Hartley Springs fault. First we combine the potential of the FEM with the Okada (1992) analytical solution for a homogeneous elastic flat half-space to validate our model. Then, to better simulate a geodynamic model of the Mono Basin, we implement more realistic dynamics that include gravity forces, vertical and lateral heterogeneities of the crust, and topography. We evaluate the distribution of local stress changes to study the influence of the Inyo dike intrusion on the Hartley Springs fault and how slip along the fault may encourage the propagation of dikes towards the surface. We employ the Coulomb stress change as a failure criterion on the Hartley Springs fault. Preliminary results indicate that slip along the Hartley Springs fault may have encouraged the intrusion of the Mono Dike.