Ground motions from induced earthquakes in Oklahoma and Kansas: implications for seismic hazard

Morgan P. Moschetti, Steven Rennolet, Eric M. Thompson, William Yeck, Dan McNamara, Robert Herrmann, Peter M. Powers, & Susan Hoover

Submitted August 15, 2016, SCEC Contribution #6815, 2016 SCEC Annual Meeting Poster #271

Recent efforts to characterize the seismic hazard resulting from increased seismicity rates in Oklahoma and Kansas highlight the need for a regionalized ground motion characterization. To support these efforts, we measure and compile strong ground motions and compare these average ground motion intensity measures (IMs) with existing ground motion prediction equations (GMPEs). IMs are computed for available broadband and strong-motion records from M≥3 earthquakes occurring January 2009–April 2016, using standard strong motion processing guidelines. We verified our methods by comparing results from specific earthquakes to other standard procedures such as the USGS Shakemap system. The large number of records required an automated processing scheme, which was complicated by the extremely high rate of small-magnitude earthquakes 2014–2016. Orientation-independent IMs (RotD50, RotD100) include peak ground motions (acceleration and velocity) and pseudo-spectral accelerations (5 percent damping, 0.1–10 s period). Metadata for the records included relocated event hypocenters. The database includes more than 160,000 records from about 3200 earthquakes. Estimates of the mean and standard deviation of the IMs are computed by distance binning at intervals of 2 km. Mean IMs exhibit a clear break in geometrical attenuation at epicentral distances of about 50–70 km, which is consistent with previous studies in the CEUS. Comparisons of these ground motions with modern GMPEs provide some insight into the relative IMs of induced earthquakes in Oklahoma and Kansas relative to the western U.S. and the central and eastern U.S. The site response for these stations is uncertain because very little is known about shallow seismic velocity in the region, and we make no attempt to correct observed IMs to a reference site conditions. At close distances, the observed IMs are lower than the predictions of the seed GMPEs of the NGA-East project (and about consistent with NGA-West-2 ground motions). This ground motion database may be used to inform future seismic hazard forecast models and in the development of regionally appropriate GMPEs.

Key Words
induced earthquakes, ground motions

Citation
Moschetti, M. P., Rennolet, S., Thompson, E. M., Yeck, W., McNamara, D., Herrmann, R., Powers, P. M., & Hoover, S. (2016, 08). Ground motions from induced earthquakes in Oklahoma and Kansas: implications for seismic hazard. Poster Presentation at 2016 SCEC Annual Meeting.


Related Projects & Working Groups
Ground Motion Prediction (GMP)