Thermally Induced Deformation and Seismicity

Kyungjae Im, & Jean-Philippe Avouac

Submitted August 13, 2019, SCEC Contribution #9526, 2019 SCEC Annual Meeting Poster #074

Thermal stress perturbation due to geothermal operation is slow, but the associated stress changes can be significant and could contribute substantially to fracturing, reactivation of pre-existing faults and surface deformation. Furthermore, the induced fault reactivation, whether seismic of aseismic, can increase the reach at which earthquakes can be triggered. Here, we investigate these issues using numerical simulations inspired by the example of the Brawley Geothermal Field operation where surface deformation and seismicity is documented [Wei et al., 2015]. We model injection in a domain, the ‘reservoir’, with poroelastic properties and finite plastic strength, embedded within a larger elastic domain (quasi-infinite half space). We analyze the effect on surface deformation and stress redistribution of a pre-existing normal fault within the reservoir. Simulation results demonstrate that the stress change due to heat production is slow but accumulates to large values with time. The accumulated stress can slowly reactivate nearby faults. The fault reactivation, together with thermal contraction induces significant ground subsidances. Finally, our simulation demonstrates that the fault reactivation can perturb stress at deeper zone and potentially destabilizes deeper faults.

Citation
Im, K., & Avouac, J. (2019, 08). Thermally Induced Deformation and Seismicity. Poster Presentation at 2019 SCEC Annual Meeting.


Related Projects & Working Groups
Seismology