TY - JOUR
T1 - Extension of continental crust by anelastic deformation during the 2011 Tohoku-oki earthquake
T2 - The role of extensional faulting in the generation of a great tsunami
AU - Tsuji, Takeshi
AU - Kawamura, Kiichiro
AU - Kanamatsu, Toshiya
AU - Kasaya, Takafumi
AU - Fujikura, Katsunori
AU - Ito, Yoshihiro
AU - Tsuru, Tetsuro
AU - Kinoshita, Masataka
N1 - Funding Information:
We thank the shipboard scientists and technical staff of cruises YK08-06, YK11-04E, YK11-06E, and YK12-13 of R/V Yokosuka (JAMSTEC). We especially thank K. Arai (Chiba University), and Y. Masaki and W. Tanikawa (JAMSTEC) for their help during the research cruise. Seismic data were acquired by R/V Kairei (JAMSTEC). R. von Huene (University of California, Davis), D. Tappin (British Geological Survey) and anonymous reviewer gave us very helpful comments. This study was supported by a Grant-in-Aid for Scientific Research on Innovative Areas from the Japan Society for the Promotion of Science (JSPS) ( 21107003) . T. Tsuji gratefully acknowledges the support of the International Institute for Carbon Neutral Energy Research ( WPI-I2CNER ), sponsored by the World Premier International Research Center Initiative (WPI), MEXT, Japan.
Copyright:
Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2013/2/5
Y1 - 2013/2/5
N2 - Observations of seafloor morphologies and environments made before and after the 2011 Tohoku-oki earthquake reveal open fissures, generated during the earthquake, where the fault trace is interpreted on seismic profiles to intersect the seafloor. Anomalously high heat flow was observed at a landward-dipping normal fault in August 2011, five months after the earthquake, but by August 2012 heat flow measured at the same station had decreased to close to the background value, which suggests that the normal fault ruptured during the 2011 earthquake. These seafloor observations and measurements demonstrate deformation that was both extensional and anelastic within the overriding continental plate during the 2011 earthquake. Seismic profiles as well as seafloor bathymetry data in the tsunami source area further demonstrate that landward-dipping normal faults (extensional faults) collapse the continental framework and detach the seaward frontal crust from the landward crust at far landward from the trench. The extensional and anelastic deformation (i.e., normal faulting) observed in both seafloor observations and seismic profiles allows the smooth seaward movement of the continental crust. Seaward extension of the continental crust close to the trench axis in response to normal faulting is a characteristic structure of tsunami source areas, as similar landward-dipping normal faults have been observed at other convergent plate margins where tsunamigenic earthquakes have occurred. We propose that the existence of a normal fault that moves the continental crust close to the trench can be considered one indicator of a source area for a huge tsunami.
AB - Observations of seafloor morphologies and environments made before and after the 2011 Tohoku-oki earthquake reveal open fissures, generated during the earthquake, where the fault trace is interpreted on seismic profiles to intersect the seafloor. Anomalously high heat flow was observed at a landward-dipping normal fault in August 2011, five months after the earthquake, but by August 2012 heat flow measured at the same station had decreased to close to the background value, which suggests that the normal fault ruptured during the 2011 earthquake. These seafloor observations and measurements demonstrate deformation that was both extensional and anelastic within the overriding continental plate during the 2011 earthquake. Seismic profiles as well as seafloor bathymetry data in the tsunami source area further demonstrate that landward-dipping normal faults (extensional faults) collapse the continental framework and detach the seaward frontal crust from the landward crust at far landward from the trench. The extensional and anelastic deformation (i.e., normal faulting) observed in both seafloor observations and seismic profiles allows the smooth seaward movement of the continental crust. Seaward extension of the continental crust close to the trench axis in response to normal faulting is a characteristic structure of tsunami source areas, as similar landward-dipping normal faults have been observed at other convergent plate margins where tsunamigenic earthquakes have occurred. We propose that the existence of a normal fault that moves the continental crust close to the trench can be considered one indicator of a source area for a huge tsunami.
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U2 - 10.1016/j.epsl.2012.12.038
DO - 10.1016/j.epsl.2012.12.038
M3 - Article
AN - SCOPUS:84873472145
VL - 364
SP - 44
EP - 58
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
SN - 0012-821X
ER -