Risk-Informed Recommendations for Managing Hydraulic Fracturing–Induced Seismicity via Traffic Light Protocols

Abstract

ABSTRACT Risks from induced earthquakes caused by hydraulic fracturing are a growing concern with a need for effective management. Here, we develop a risk-informed strategy for choosing red and yellow traffic light thresholds based on the current understanding of induced earthquakes. To do so, we utilize probabilistic maximum magnitudes, magnitude to ground-motion relationships, population densities, statistical distributions of site amplification, and felt or damaging ground-motion thresholds to compute the risk of damage or nuisance. Risk curves for various forecast scenarios highlight two proposed guidelines. First, setting red-light thresholds within the nuisance range of ground motions reduces the chances that runaway earthquakes could cause unacceptable damage. Second, setting yellow-light thresholds approximately two magnitude units less than the red light ensures that operators have a sufficient opportunity to enact mitigation strategies. We compare the differences in risk between several real-life traffic light cases to illustrate how this approach could allow regulators to design traffic light protocols in a risk-informed manner and thus balance the consequences of their decisions more effectively. Our approach also promotes the transparent communication of risk to all involved stakeholders.