Numerical models of volcanotectonic earthquake triggering on non‐ideally oriented faults

Abstract

Calculation of inflation‐induced Coulomb stress changes on faults of varying orientation indicates that local faults of almost any orientation are susceptible to slip in response to dike inflation. Additionally, as dikes typically inflate in the direction of regional minimum compressive stress, the sense of inflation‐induced strike‐slip faulting predicted by Coulomb stress change models is opposite to that expected from regional tectonic forces. Observations of volcanotectonic (VT) earthquake fault‐plane solutions with pressure (p‐) axes oriented ∼90° to regional maximum compression confirm this prediction. In detail, imperfect agreement between Coulomb stress change models and the ranges of fault‐plane orientations observed in VT fault‐plane solution studies and observed locations of VT seismicity indicates that the orientation and location of pre‐existing faults around the conduit ultimately determine the seismic response of host rock to an inflating dike.