Research Article| July 01, 2009 Megathrust earthquakes can nucleate in the forearc mantle: Evidence from the 2004 Sumatra event J.-X. Dessa; J.-X. Dessa 1GéoAzur, Université Pierre et Marie Curie, CNRS-IRD-UNS, 2 quai de la Darse, BP 48, F-06235 Villefranche-sur-Mer, France Search for other works by this author on: GSW Google Scholar F. Klingelhoefer; F. Klingelhoefer 2IFREMER, BP 70, F-29280 Plouzané, France Search for other works by this author on: GSW Google Scholar D. Graindorge; D. Graindorge 3Institut Universitaire Européen de la Mer (UBO), Technopôle Brest-Iroise, Place Nicolas Copernic, F-29280 Plouzané, France Search for other works by this author on: GSW Google Scholar C. André; C. André 3Institut Universitaire Européen de la Mer (UBO), Technopôle Brest-Iroise, Place Nicolas Copernic, F-29280 Plouzané, France Search for other works by this author on: GSW Google Scholar H. Permana; H. Permana 4Research Center for Geotechnology-LIPI, Bandung, 40135, Indonesia Search for other works by this author on: GSW Google Scholar M.-A. Gutscher; M.-A. Gutscher 3Institut Universitaire Européen de la Mer (UBO), Technopôle Brest-Iroise, Place Nicolas Copernic, F-29280 Plouzané, France Search for other works by this author on: GSW Google Scholar A. Chauhan; A. Chauhan 5Institut de Physique du Globe de Paris, 4 place Jussieu, F-75252, Paris, France Search for other works by this author on: GSW Google Scholar S. C. Singh; S. C. Singh 5Institut de Physique du Globe de Paris, 4 place Jussieu, F-75252, Paris, France Search for other works by this author on: GSW Google Scholar the SUMATRA-OBS Scientific Team the SUMATRA-OBS Scientific Team Search for other works by this author on: GSW Google Scholar Geology (2009) 37 (7): 659–662. https://doi.org/10.1130/G25653A.1 Article history received: 07 Nov 2008 rev-recd: 06 Feb 2009 accepted: 05 Mar 2009 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation J.-X. Dessa, F. Klingelhoefer, D. Graindorge, C. André, H. Permana, M.-A. Gutscher, A. Chauhan, S. C. Singh, the SUMATRA-OBS Scientific Team; Megathrust earthquakes can nucleate in the forearc mantle: Evidence from the 2004 Sumatra event. Geology 2009;; 37 (7): 659–662. doi: https://doi.org/10.1130/G25653A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Current models predict that the seismogenic zone along subduction thrusts, where the largest earthquakes nucleate and propagate, does not extend to the forearc mantle below the crust of the upper plate. Stable sliding conditions have been shown to prevail there, particularly along several circum-Pacific margins that underwent great megathrust earthquakes (Mw > 8.5) during the twentieth century. Based on geophysical investigation, we show that the great 2004 Sumatra-Andaman earthquake (Mw = 9–9.3) contradicts these models: not only did it propagate downdip along the interface between the forearc mantle and the subducting plate, but it actually nucleated along this reportedly aseismic part of the interplate contact. Petrological models can therefore underestimate the downdip extent of rupture zones to be expected in megathrust earthquakes, and need to be revised to account for this observation, albeit unusual. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.