Assessing Potential Ground-Motion Hazards from Induced Earthquakes

Earthquakes induced by the hydraulic fracturing and fluid injections pose hazards to communities in the United States, Canada, as well as other places in the world. Although several types of hazards can be generated by an induced earthquake, ground motion is the main concern. Assessing ground-motion hazards from induced earthquakes is not easy because there are large uncertainties inherited in the estimates of the locations, magnitudes, and recurrence intervals of earthquakes, as well as ground motion. The challenge for assessing ground-motion hazards is not only on how to quantify the uncertainties, but also how to communicate them. There are a variety of approaches currently being used for ground motion hazard assessment, ranging from complete, explicit consideration of all the uncertainties, partial, explicit consideration of the uncertainties, to simple, explicit consideration of certain uncertainties. A scenario-based seismic hazard analysis (SSHA) was applied to estimate ground motions from induced earthquakes in Oklahoma and Kentucky. Utilizing ground-motion simulations, SSHA can account for earthquake source characteristics, ground-motion propagation, and site effects, as well as related uncertainties (i.e., mean, median, or a specific percentile), explicitly. The results from SSHA, including acceleration, velocity, and displacement time histories, are easy to communicate, understand, and use.