Statistical bounds on how induced seismicity stops

Earthquakes caused by human activities receive scrutiny due to the risks and hazards they pose. Seismicity that occurs after the causative anthropogenic operation stops has been particularly problematic-both because of high-profile cases of damage caused by this trailing seismicity and due to the loss of control for risk management. With this motivation, we undertake a statistical examination of how induced seismicity stops. We borrow the concept of Bath's law from tectonic aftershock sequences. Bath's law anticipates the difference between magnitudes in two subsets of seismicity as dependent on their population count ratio. We test this concept for its applicability to induced seismicity, including similar to 80 cases of earthquakes caused by hydraulic fracturing, enhanced geothermal systems, and other fluid-injections with clear operational end points. We find that induced seismicity obeys Bath's law: both in terms of the magnitude-count-ratio relationship and the power law distribution of residuals. Furthermore, the distribution of count ratios is skewed and heavy-tailed, with most earthquakes occurring during stimulation/injection. We discuss potential models to improve the characterization of these count ratios and propose a Seismogenic Fault Injection Test to measure their parameters in situ. We conclude that Bath's law quantifies the occurrence of earthquake magnitudes trailing anthropogenic operations.

Automated summary

This study examines how induced seismicity stops and finds that Bath's law, which predicts the difference in magnitudes based on population count ratio, applies to induced seismicity. The study also reveals that count ratios in induced seismicity follow a skewed and heavy-tailed distribution, with most earthquakes occurring during stimulation/injection.