Toward physics-based seismic hazard assessments: A holistic approach to understanding the physics of induced earthquakes

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Earthquakes, which result from the movements of faults in the subsurface, are of scientific and societal interest due to their destructive potential. Because of the abrupt and complex nature of the dynamic process, as well as the opacity of the deforming crust, it remains a challenge to obtain a comprehensive, physics-based understanding of earthquakes. In particular, seismicity that points to an anthropogenic origin is becoming the focus of scientific and political discussions, with multiple published studies suggesting its correlation with fluid-injection activities associated with unconventional hydrocarbon production and geothermal energy. This is a pressing issue, because many induced earthquakes occur in populated regions that are considered seismically dormant and unprepared for any form of strong shaking. At present, the underlying physical mechanisms of induced earthquakes remain elusive and current seismic hazard maps rely mostly on statistical analyses of existing earthquake catalogues. A quantitative predictive model requires deeper investigation into the physics of induced earthquakes. My research program is to advance the understanding of seismic source processes and fault rupture dynamics, with a primary focus on induced seismicity. Recent advancements in seismic instrumentations and high-performance computing have allowed geoscientists to strive toward a more profound and practical understanding to earthquakes. In the next five years, we will address several key issues: (1) Characterizing the role of injection and frictional parameters in earthquake triggering, (2) Illuminating features of the host geological environment, (3) Modeling of the triggered ground motions, (4) Quantifying the effect of different possible triggering mechanisms on induced seismicity, (5) Characterizing the interplay of seismic and aseismic slip in long-term earthquake cycles. The research will be innovative and distinct among induced seismicity studies by taking a holistic approach that investigates induced seismicity at multiple scales and from multiple angles by combining field observations, laboratory experiments, and computational modeling. The characterization of seismic sources through observables (field and lab data) will serve as the basis for constructing realistic physically-based predictive models with state-of-the-art numerical tools. The numerical models we use are governed by sophisticated empirical friction laws and will bridge the gap among seismic observations at various scales, bringing a comprehensive understanding to the physics of induced earthquakes. Through international collaborations with seismologists and rock engineers, my program will contribute to improving hazard mitigation and to formulating clear industry regulations and investment strategies. Advancing the science of induced seismicity will also make significant contributions to our knowledge of large-magnitude earthquake nucleation and triggering in natural earthquakes.