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Application of Seismic Array Processing to Earthquake Early Warning

Meng, L. and Allen, R. M. and Ampuero, J.-P. (2014) Application of Seismic Array Processing to Earthquake Early Warning. Bulletin of the Seismological Society of America, 104 (5). pp. 2553-2561. ISSN 0037-1106. http://resolver.caltech.edu/CaltechAUTHORS:20141201-084550766

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Abstract

Earthquake early warning (EEW) systems that issue warnings prior to the arrival of strong shaking are essential in mitigating earthquake hazard. Currently operating EEW systems work on point‐source assumptions and are of limited effectiveness for large events, for which ignoring finite‐source effects result in magnitude underestimation. Here, we explore the concept of characterizing rupture dimensions in real time for EEW using small‐aperture seismic arrays located near active faults. Back tracing array waveforms allow estimation of the extent of the rupture front (as a proxy of the rupture size) and directivity in real time, providing complementary EEW capabilities for M>7 earthquakes to existing EEW systems. We implement it in a simulated real‐time environment and analyze the 2004 M 6 Parkfield, California, earthquake recordings by the U.S. Geological Survey Parkfield dense Seismograph ARray (UPSAR) array and the 2010 M 7.2 El Mayor–Cucapah earthquake recordings by strong‐motion sensors in San Diego, California. We find it important to correct for the bias in back azimuth induced by dipping structures beneath the UPSAR array, based on data from smaller events. Our estimated rupture length is 30% shorter than those inferred from other studies but still reasonable for EEW purposes. We attribute this difference to rupture directivity effects and the limited field of view of a single array. The accuracy of the approach may be improved with a network of arrays with overlapping fields of view. We demonstrate this by tracking the 2011 Tohoku earthquake rupture with two clusters of Hi‐net stations in Kyushu and northern Hokkaido. The obtained results are consistent with teleseismic back‐projection results and yield reasonable estimates of rupture length and directivity. Compared with other proposed finite‐fault EEW approaches, the array method is less affected by the coarseness of a Global Positioning System or seismic network and provides a high‐frequency characterization of the rupture that yields more suitable predictors of ground shaking for certain structures.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1785/0120130277DOIArticle
http://www.bssaonline.org/content/104/5/2553PublisherArticle
http://bssa.geoscienceworld.org/content/104/5/2553PublisherArticle
ORCID:
AuthorORCID
Ampuero, J.-P.0000-0002-4827-7987
Additional Information:© 2014 Seismological Society of America. Manuscript received 25 October 2013; Published Online 16 September 2014. This work was funded by the Gordon and Betty Moore Foundation through Grant GBMF3024 to University of California Berkeley. We thank Nathan Simmons for valuable discussions about the dipping layer effect. We thank Paul Spudich and Joe Fletcher for providing the back-azimuth estimates of the 2004 Parkfield earthquake and its aftershocks.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
Gordon and Betty Moore FoundationGBMF3024
Record Number:CaltechAUTHORS:20141201-084550766
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20141201-084550766
Official Citation:L. Meng, R. M. Allen, and J.‐P. Ampuero Application of Seismic Array Processing to Earthquake Early Warning Bulletin of the Seismological Society of America, October 2014, v. 104, p. 2553-2561, First published on September 16, 2014, doi:10.1785/0120130277
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:52196
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:01 Dec 2014 18:14
Last Modified:17 Sep 2015 20:02

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