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Earthquake source parameter validation using multiple-scale approaches for induced seismicity in Oklahoma

Rachel E. Abercrombie, & Xiaowei Chen

Published August 15, 2016, SCEC Contribution #7003, 2016 SCEC Annual Meeting Poster #063

The rapid increased seismicity rate in central US has drawn significant attention to the associated earthquake hazards in intraplate regions. Whether induced earthquakes have similar stress drops to tectonic events is an important question for understanding both the earthquake rupture process, and the hazard they represent. To address this question, we study well-recorded earthquake sequences in Oklahoma, including clusters near both Guthrie, and Prague.

For each cluster, we apply both a stacking-based empirical Green’s function method and an individual-pair based method to both P and S waves. Significant effort has been devoted to improve the stability of the stacking approach. We carefully examine variations of the average stress drop for each cluster with different choices of signal-to-noise ratio, minimum requirement of stations, number of events, magnitude bins included in stacking, and frequency band limits, in order to assess a range of parameter choices that provide stable estimations. In the stacking approach, the average stress drop would shift the individual stress drop systematically. Although this would generally preserve the relative variations, this could be problematic when comparing sequences from different regions.

We then compare the optimal stacking result with individual-pair analysis for common events. For the latter method, we also investigate how to obtain and identify the best results using multiple EGFs and stations. For the Guthrie clusters, we obtain striking consistency over a wide range of magnitudes, and consistent average stress drop. Some parameter combinations affect the average stress drop, which may appear anomalously low or high. We continue to analyze other sequences to optimize the algorithms. The stress drop results will help us to understand the variations of fault strength and relationship with pore pressure propagation.

Key Words
Earthquake, Induced, stress drop

Abercrombie, R. E., & Chen, X. (2016, 08). Earthquake source parameter validation using multiple-scale approaches for induced seismicity in Oklahoma. Poster Presentation at 2016 SCEC Annual Meeting.

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)