SCEC2021 Poster #204: Correlation between Aλ fault parameter and statistical frequency of earthquakes along depth: a case study in Southern California

Poster #204, Seismology

Correlation between Aλ fault parameter and statistical frequency of earthquakes along depth: a case study in Southern California

Andrea Carducci, Antonio Petruccelli, Angelo De Santis, Rita de Nardis, & Giusy Lavecchia

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Poster Presentation

2021 SCEC Annual Meeting, Poster #204, SCEC Contribution #11410 VIEW PDF

Using a relocated earthquake catalog and focal mechanisms from Southern California, we investigated a connection between statistical frequency-magnitude relation from Gutenberg-Richter equation, also known as b-value and Aλ: this is a quantification of fault kinematics, closely related to Andersonian fault parameter Aϕ; however, while Aϕ is calculated from shape ratio and faulting type, Aλ values are instead strictly dependent on rake values. We think that Aλ may help us to find an equation to explain b-value distributions according to kinematic features and depth.
We merged the coordinates of SCSN relocated earthquakes by Hauksson, Yang and Shearer with features from focal mechanisms... compiled by the same authors, to obtain a large focal mechanism dataset (from ~56700 of highest quality up to ~238400 for lowest quality ones); its spatial resolution was sufficient to investigate b-values along depth for well distinguished kinematic classes. We also analyzed how frequency-magnitude relates to the stress field of Southern California, especially comparing results from mostly linear rheology depth ranges against creep-power law dominated depths. We then performed multiple regressions of b-value vs Aλ at various depth ranges and tested their statistical significance. The equation we found could help formulate models for frequency-magnitude distributions in three-dimensional space, useful for seismic hazard assessment.
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