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Asperities and barriers on the seismogenic zone in North Chile: state-of-the-art after the 2007 Mw 7.7 Tocopilla earthquake inferred by GPS and InSAR data

Béjar-Pizarro, M. and Carrizo, D. and Socquet, A. and Armijo, R. and Barrientos, S. and Bondoux, F. and Bonvalot, S. and Campos, J. and Comte, D. and de Chabalier, J. B. and Charade, O. and Delorme, A. and Gabalda, G. and Galetzka, J. and Genrich, J. and Nercessian, A. and Olcay, M. and Ortega, F. and Ortega, I. and Remy, D. and Ruegg, J. C. and Simons, M. and Valderas, C. and Vigny, C. (2010) Asperities and barriers on the seismogenic zone in North Chile: state-of-the-art after the 2007 Mw 7.7 Tocopilla earthquake inferred by GPS and InSAR data. Geophysical Journal International, 183 (1). pp. 390-406. ISSN 0956-540X. https://resolver.caltech.edu/CaltechAUTHORS:20101013-081748691

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Abstract

The Mw 7.7 2007 November 14 earthquake had an epicentre located close to the city of Tocopilla, at the southern end of a known seismic gap in North Chile. Through modelling of Global Positioning System (GPS) and radar interferometry (InSAR) data, we show that this event ruptured the deeper part of the seismogenic interface (30–50 km) and did not reach the surface. The earthquake initiated at the hypocentre and was arrested ~150 km south, beneath the Mejillones Peninsula, an area already identified as an important structural barrier between two segments of the Peru–Chile subduction zone. Our preferred models for the Tocopilla main shock show slip concentrated in two main asperities, consistent with previous inversions of seismological data. Slip appears to have propagated towards relatively shallow depths at its southern extremity, under the Mejillones Peninsula. Our analysis of post-seismic deformation suggests that small but still significant post-seismic slip occurred within the first 10 d after the main shock, and that it was mostly concentrated at the southern end of the rupture. The post-seismic deformation occurring in this period represents ~12–19 per cent of the coseismic deformation, of which ~30–55 per cent has been released aseismically. Post-seismic slip appears to concentrate within regions that exhibit low coseismic slip, suggesting that the afterslip distribution during the first month of the post-seismic interval complements the coseismic slip. The 2007 Tocopilla earthquake released only ~2.5 per cent of the moment deficit accumulated on the interface during the past 130 yr and may be regarded as a possible precursor of a larger subduction earthquake rupturing partially or completely the 500-km-long North Chile seismic gap.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1111/j.1365-246X.2010.04748.x DOIArticle
ORCID:
AuthorORCID
Simons, M.0000-0003-1412-6395
Additional Information:© 2010 The Authors. Geophysical Journal International © 2010 RAS. Accepted 2010 July 20. Received 2010 July 19; in original form 2009 December 18. We thankMatt Pritchard, an anonymous reviewer and EditorDuncan Agnew for thorough reviews that helped to improve the manuscript. This work was performed in the frame of the French/Chilean international collaboration (CNRS/CONICYT LIA ‘Montessus de Ballore’). We thank the European Space Agency (ESA) for providing the ENVISAT images (project AO-720). This work was made possible thanks to the funding of the French National Research Agency (ANR-05-CATT-014, ANR-06-CATT-010-01), CNRS/INSU (funding of post-seismic task force), ARCUS project and BQR IPGP. The Caltech component of the GPS network was made possible by support from the Gordon and Betty Moore Foundation. MBP was partly supported by a grant of the Universidad Complutense de Madrid, CNRS and an Eiffel fellowship. DC was supported by an Ile-de- France Postdoctoral Fellowship and IPGP. GMT was used to create most of the figures (Wessel & Smith 1998). We thank C. Lasserre and R. Grandin for the linear inversion code. We thank S. Peyrat, P. Bernard, J.P. Vilotte, R. Madariaga, M. Sobiesiak, R. Lacassin, A. Coudurier Curveur and J.J. Martínez-Díaz for scientific discussion. This is IPGP contribution number 3032.
Funders:
Funding AgencyGrant Number
French National Research Agency ANR-05-CATT-014
French National Research Agency ANR-06-CATT-010-01
Centre National de la Recherche Scientifique/Institut national des sciences de l'Univers (CNRS/INSU) UNSPECIFIED
Arctic Research Consortium of the U.S. (ARCUS) UNSPECIFIED
BQR IPGP UNSPECIFIED
Gordon and Betty Moore Foundation UNSPECIFIED
Universidad Complutense de Madrid UNSPECIFIED
Eiffel fellowship UNSPECIFIED
Ile-de-France Postdoctoral Fellowship UNSPECIFIED
Institut de Physique du Globe de Paris (IPGP) UNSPECIFIED
Subject Keywords:Satellite geodesy; Earthquake ground motions; Subduction zone processes; South America
Issue or Number:1
Record Number:CaltechAUTHORS:20101013-081748691
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20101013-081748691
Official Citation:Béjar-Pizarro, M., Carrizo, D., Socquet, A., Armijo, R., Barrientos, S., Bondoux, F., Bonvalot, S., Campos, J., Comte, D., De Chabalier, J. B., Charade, O., Delorme, A., Gabalda, G., Galetzka, J., Genrich, J., Nercessian, A., Olcay, M., Ortega, F., Ortega, I., Remy, D., Ruegg, J. C., Simons, M., Valderas, C. and Vigny, C. (2010), Asperities and barriers on the seismogenic zone in North Chile: state-of-the-art after the 2007 Mw 7.7 Tocopilla earthquake inferred by GPS and InSAR data. Geophysical Journal International, 183: 390–406. doi: 10.1111/j.1365-246X.2010.04748.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:20413
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:23 Nov 2010 20:17
Last Modified:03 Oct 2019 02:09

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