Poster #242, Seismology
Source complexity of small and moderate earthquakes in the 2019 Ridgecrest earthquake sequence
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Poster Presentation
2021 SCEC Annual Meeting, Poster #242, SCEC Contribution #11635 VIEW PDF
the dataset organized for the community stress drop validation project, we combine both frequency and time domain analyses based on the empirical Green’s function (EGF) technique to investigate the source processes for selected M2-5 earthquakes. In the frequency domain, we apply the multiple spectral ratio method on all potential target events with M ≥ 2 in the Ridgecrest sequence to measure corner frequencies of the target events. We quantify the complexity of the stacked spectral ratios by examining their deviation from the simple omega-square source model. We also apply an improved stacking method to estimate corner frequencies and compute stress drops. In the time domain, we apply an iterative deconvolution method to retrieve relative source time functions (RSTFs), from which we quantify possible directivity effects and the existence of multiple subevents when applicable. Combining the STF and spectral ratio results, we will classify the analyzed events into “simple” and “complex” categories. Stress drop estimates from the two types of spectral analysis will be compared and then be examined jointly and separately for the two classified categories to investigate the effects of source complexity on the variability of stress drop estimates. Our results will contribute to a better understanding of fundamental earthquake rupture processes, and the limitations of Brune-type simple source model in estimating source parameters such as stress drop and source dimension and the influence on ground motion predictions.
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