Seismic slip propagation to the up-dip end of plate boundary subduction interface faults: Vitrinite reflectance geothermometry on IODP NanTroSEIZE cores

Arito Sakaguchi , Frederick Chester , Daniel Curewitz , Olivier Fabbri (1) , David Goldsby , Gaku Kimura , Chun-Feng Li , Yuka Masaki , Elizabeth Screaton (2) , A. Tsutsumi (3) , Kohtaro Ujiie (4) , Asuka Yamaguchi

1 LCE - Laboratoire Chrono-environnement (UMR 6249)
2 Department of Geology
3 Department of Geology and Mineralogy
4 Université de Tsukuba = University of Tsukuba

Seismic faulting along subduction-type plate boundaries plays a fundamental role in tsunami genesis. During the Integrated Ocean Drilling Program (IODP) Nankai Trough Seismogenic Zone Experiment (NanTro SEIZE) Stage 1, the updip ends of plate boundary subduction faults were drilled and cored in the Nankai Trough (offshore Japan), where repeated large earthquakes and tsunamis have occurred, including the A.D. 1944 Tonankai (Mw = 8.1) earthquake. Samples were obtained from the frontal thrust, which connects the deep plate boundary to the seafl oor at the toe of the accretionary wedge, and from a megasplay fault that branches from the plate boundary décollement. The toe of the accretionary wedge has classically been considered aseismic, but vitrinite refl ectance geothermometry reveals that the two examined fault zones underwent localized temperatures of more than 380 C. This suggests that frictional heating occurred along these two fault zones, and implies that coseismic slip must have propagated at least one time to the updip end of the megasplay fault and to the toe of the accretionary wedge

Domaines: Tectonique; Milieux et Changements globaux

Arito Sakaguchi, Frederick Chester, Daniel Curewitz, Olivier Fabbri, David Goldsby, et al.. Seismic slip propagation to the up-dip end of plate boundary subduction interface faults: Vitrinite reflectance geothermometry on IODP NanTroSEIZE cores. Geology, 2011, 39 (4), pp.395-398. ⟨10.1130/G31642.1⟩. ⟨hal-00657512⟩