Focal Mechanism, Magnitude, and Finite-Fault Rapid Estimation Using the Elliptical Patch Method in Chile

F. Leyton, S. Ruiz, and R. Madariaga

Penerbit : Seismological Research Letters

Tahun : 2018

Nowadays, most fast, automatic algorithms estimate the magnitude and location of earthquakes assuming a point-source approximation that might produce large errors in the predicted shaking. In this study, using a kinematic approach, we modeled the fault plane as an elliptical patch with a Gaussian slip distribution to perform a rapid estimation of the finite fault, focal mechanism, and moment magnitude. We implemented this finite-fault kinematic inversion using data from the Centro Sismológico Nacional of the Universidad de Chile. We used near-field data, up to 600 km from the epicenter, mostly from accelerograms and a few nonsaturated broadband records. By considering data up to 5 min from the origin time, we are able to retrieve relevant source parameters within 10–15 min from the occurrence of the event. This elliptical patch method (EPM) successfully resolves the source parameters for 45 moderate-to-large events, from 2013 to 2017 (magnitudes ranging from 6.0 to 8.3). These results encourage the use of the EPM in the rapid response to moderate-to-large earthquakes in subduction zones.

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