A Preliminary Analysis of In-Situ Stress at Mount Meager by Displacement Discontinuity Method with Topography and Tectonics Considered

Abstract

Geothermal energy is one of the most stable and clean solutions to replace the traditional fossil fuel energy resource. The South Meager geothermal prospect, located in southwestern British Columbia, contains large geothermal energy resources due to recent volcanic activities. The in-situ stress state in the prospective area that influences the characteristics of fractures, thus affecting productivity, remains unknown. In this paper, we present a preliminary analysis of in-situ stress induced by gravitational load at Mount Meager, with tectonics considered. The in-situ stress model was constructed with 3D displacement discontinuity method based on the site-specific topography. The 3D model reveals that the impact of topography is more prominent in shallow and deep regions, while the impact of tectonics is prominent in an intermediate depth range. With the implementation of inferred tectonic stress state, normal faulting regime takes place at shallow depth (<800 m); at the intermediate depth (800–1600 m), the transition of faulting regime from normal to strike-slip and then to thrust occurs; at deeper depth (>1800 m), the fault type becomes normal again. The orientations of major and minor induced horizontal stresses transition from varying with local topography to perfectly aligned with the orientations of major and minor horizontal tectonic stresses at NWN-SES 330° and NEE-SWW 60°, respectively, as depth increases.