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Detecting periodicities and declustering in earthquake catalogs using the Schuster spectrum, application to Himalayan seismicity

Ader, Thomas J. and Avouac, Jean-Philippe (2013) Detecting periodicities and declustering in earthquake catalogs using the Schuster spectrum, application to Himalayan seismicity. Earth and Planetary Science Letters, 377 . pp. 97-105. ISSN 0012-821X. http://resolver.caltech.edu/CaltechAUTHORS:20131101-080433258

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Abstract

We show that the Schuster test alone does not provide a sufficient condition to assert the existence of a periodicity in an earthquake catalog. Such periodicities can be detected by computing a spectrum of Schuster p-values (the probability to observe such a level of periodic variations in a catalog occurring out of a constant seismicity rate). We show that the detection level is slightly period dependent, and we provide an analytical expression relating the amplitude of seismicity-rate variations to the confidence level at which the probability that the observed variations be due to chance can be discarded. The Schuster spectrum also provides information about the deviation from a sinusoidal function of the periodicity of the seismicity rate, and identifies an eventual imperfect declustering of the catalog, making it coincidently a potential tool to determine whether or not a catalog has been properly declustered. Applying this tool to the Nepalese seismicity, we demonstrate annual variations of the seismicity rate of amplitude up to 40%, while no other periodicity appears. In particular, no variations of seismicity at any of the tidal periods are observed, indicating that the relative amplitude response of the seismicity at these periods is less than 18%.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://www.sciencedirect.com/science/article/pii/S0012821X13003555PublisherArticle
http://dx.doi.org/10.1016/j.eps1.2013.06.032 DOIArticle
Additional Information:© 2013 Published by Elsevier B.V. Received 18 October 2012; Received in revised form 13 June 2013; Accepted 23 June 2013; Available online 17 July 2013. We thank Francisco Ortega for his help in writing some of the algorithms for the simulations, run on the parallel computer Fram available at Caltech. This project was supported by the Gordon and Betty Moore Foundation, through the Tectonics Observatory, NSF grant EAR #0838495. This is Caltech Tectonic Observatory’s contribution number 230 and Caltech Seismolab contribution number 10092.
Group:Caltech Tectonics Observatory, Seismological Laboratory
Funders:
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
Caltech Tectonics ObservatoryUNSPECIFIED
NSFEAR 0838495
Subject Keywords:earthquake catalogs; periodicities; Schuster test; Schuster spectrum; Nepalese seismicity; seasonal variations
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Tectonics Observatory230
Caltech Seismolab 10092
Record Number:CaltechAUTHORS:20131101-080433258
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20131101-080433258
Official Citation:Thomas J. Ader, Jean-Philippe Avouac, Detecting periodicities and declustering in earthquake catalogs using the Schuster spectrum, application to Himalayan seismicity, Earth and Planetary Science Letters, Volumes 377–378, September 2013, Pages 97-105, ISSN 0012-821X, http://dx.doi.org/10.1016/j.epsl.2013.06.032. (http://www.sciencedirect.com/science/article/pii/S0012821X13003555)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:42169
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:01 Nov 2013 17:34
Last Modified:11 Jun 2015 13:57

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