Holocene turbidites record earthquake supercycles at a slow-rate plate boundary

Type Article
Date 2015-04
Language English
Author(s) Ratzov Gueorgui1, 2, Cattaneo AntonioORCID2, Babonneau Nathalie1, Deverchere Jacques1, Yelles Karim3, Bracene Rabah4, Courboulex Francoise5
Affiliation(s) 1 : Univ Brest, IUEM, CNRS UMR 6538, Domaines Ocean, F-29280 Plouzane, France.
2 : IFREMER, Geosci Marines EDROME, F-29280 Plouzane, France.
3 : Ctr Rech Astron Astrophys & Geophys, Algiers 16006, Algeria.
4 : SONATRACH Explorat, Boumerdes 35000, Algeria.
5 : Univ Nice Sophia Antipolis, CNRS, IRD, Observ Cote Azur,Geoazur UMR 7329, F-06560 Valbonne, France.
Source Geology (0091-7613) (Geological Soc Amer, Inc), 2015-04 , Vol. 43 , N. 4 , P. 331-334
DOI 10.1130/G36170.1
WOS© Times Cited 27
Abstract Ongoing evidence for earthquake clustering calls for records of numerous earthquake cycles to improve seismic hazard assessment, especially where recurrence times overstep historical records. We show that most turbidites emplaced at the Africa-Eurasia plate boundary off west Algeria over the past ∼8 k.y. correlate across sites fed by independent sedimentary sources, requiring a regional trigger. Correlation with paleoseismic data inland and ground motion predictions support that M ∼7 earthquakes have triggered the turbidites. The bimodal distribution of paleo-events supports the concepts of earthquake supercycles and rupture synchronization between nearby faults: 13 paleo-earthquakes underpin clusters of 3–6 events with recurrence intervals of ∼300–600 yr, separated by periods of quiescence of ∼1.6 k.y. without major events on other faults over the study area. This implies broad phases of strain loading alternating with phases of strain release. Our results suggest that fault slip rates are time dependent and call for revising conventional seismic hazard models.
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Ratzov Gueorgui, Cattaneo Antonio, Babonneau Nathalie, Deverchere Jacques, Yelles Karim, Bracene Rabah, Courboulex Francoise (2015). Holocene turbidites record earthquake supercycles at a slow-rate plate boundary. Geology, 43(4), 331-334. Publisher's official version : https://doi.org/10.1130/G36170.1 , Open Access version : https://archimer.ifremer.fr/doc/00254/36558/