Giuseppe
Emeritus
[Source: Science, full page: (LINK). Abstract, edited.]
<CITE><ABBR>Science</ABBR> 6 December 2013: Vol. 342 no. 6163 pp. 1208-1211 / DOI: 10.1126/science.1243719 </CITE>
<CITE></CITE>
<CITE></CITE>Report
Structure and Composition of the Plate-Boundary Slip Zone for the 2011 Tohoku-Oki Earthquake
Frederick M. Chester<SUP>1</SUP>,*, Christie Rowe<SUP>2</SUP>, Kohtaro Ujiie<SUP>3</SUP>, James Kirkpatrick<SUP>4</SUP>, Christine Regalla<SUP>5</SUP>, Francesca Remitti<SUP>6</SUP>, J. Casey Moore<SUP>7</SUP>, Virginia Toy<SUP>8</SUP>, Monica Wolfson-Schwehr<SUP>9</SUP>, Santanu Bose<SUP>10</SUP>, Jun Kameda<SUP>11</SUP>,?, James J. Mori<SUP>12</SUP>, Emily E. Brodsky<SUP>7</SUP>, Nobuhisa Eguchi<SUP>13</SUP>, Sean Toczko<SUP>13</SUP>, Expedition 343 and 343T Scientists?
Author Affiliations: <SUP>1</SUP>Center for Tectonophysics, Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843, USA. <SUP>2</SUP>Earth and Planetary Sciences Department, McGill University, Montreal, Canada. <SUP>3</SUP>Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan; Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan. <SUP>4</SUP>Department of Geosciences, Colorado State University, Fort Collins, CO 80523, USA. <SUP>5</SUP>Department of Geosciences, Pennsylvania State University, University Park, PA 16802, USA. <SUP>6</SUP>Dipartimento di Scienze della Terra, Universit? di Modena e Reggio Emilia largo, Modena, Italy. <SUP>7</SUP>Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, USA. <SUP>8</SUP>Department of Geology, University of Otago, Dunedin, New Zealand. <SUP>9</SUP>Center for Coastal and Ocean Mapping/Joint Hydrographic Center, University of New Hampshire, Durham, NH 03824, USA. <SUP>10</SUP>Department of Geology, University of Calcutta, Kolkata, India. <SUP>11</SUP>Department of Earth and Planetary Science, The University of Tokyo, Tokyo, Japan. <SUP>12</SUP>Earthquake Hazards Division, Disaster Prevention Research Institute, Kyoto University, Kyoto, Japan. <SUP>13</SUP>Center for Deep Earth Exploration, Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan.
*Corresponding author. E-mail: chesterf@tamu.edu
Abstract
The mechanics of great subduction earthquakes are influenced by the frictional properties, structure, and composition of the plate-boundary fault. We present observations of the structure and composition of the shallow source fault of the 2011 Tohoku-Oki earthquake and tsunami from boreholes drilled by the Integrated Ocean Drilling Program Expedition 343 and 343T. Logging-while-drilling and core-sample observations show a single major plate-boundary fault accommodated the large slip of the Tohoku-Oki earthquake rupture, as well as nearly all the cumulative interplate motion at the drill site. The localization of deformation onto a limited thickness (less than 5 meters) of pelagic clay is the defining characteristic of the shallow earthquake fault, suggesting that the pelagic clay may be a regionally important control on tsunamigenic earthquakes.
Deep Drilling for Earthquake Clues
The 2011 M<SUB>w</SUB> 9.0 Tohoku-Oki earthquake and tsunami were remarkable in many regards, including the rupturing of shallow trench sediments with huge associated slip (see the Perspective by Wang and Kinoshita). The Japan Trench Fast Drilling Project rapid response drilling expedition sought to sample and monitor the fault zone directly through a series of boreholes. Chester et al. (p. 1208) describe the structure and composition of the thin fault zone, which is predominately comprised of weak clay-rich sediments. Using these same fault-zone materials, Ujiie et al. (p. 1211) performed high-velocity frictional experiments to determine the physical controls on the large slip that occurred during the earthquake. Finally, Fulton et al. (p. 1214) measured in situ temperature anomalies across the fault zone for 9 months, establishing a baseline for frictional resistance and stress during and following the earthquake.
? Present address: Earth and Planetary System Science, Department of Natural History Sciences, Hokkaido University, N10 W8, Sapporo 060-0810, Japan.
? Expedition 343 and 343 T Scientists authors and affiliations are listed in Supplementary Materials.
Received for publication 24 July 2013.
Accepted for publication 30 October 2013.
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<CITE><ABBR>Science</ABBR> 6 December 2013: Vol. 342 no. 6163 pp. 1208-1211 / DOI: 10.1126/science.1243719 </CITE>
<CITE></CITE>
<CITE></CITE>Report
Structure and Composition of the Plate-Boundary Slip Zone for the 2011 Tohoku-Oki Earthquake
Frederick M. Chester<SUP>1</SUP>,*, Christie Rowe<SUP>2</SUP>, Kohtaro Ujiie<SUP>3</SUP>, James Kirkpatrick<SUP>4</SUP>, Christine Regalla<SUP>5</SUP>, Francesca Remitti<SUP>6</SUP>, J. Casey Moore<SUP>7</SUP>, Virginia Toy<SUP>8</SUP>, Monica Wolfson-Schwehr<SUP>9</SUP>, Santanu Bose<SUP>10</SUP>, Jun Kameda<SUP>11</SUP>,?, James J. Mori<SUP>12</SUP>, Emily E. Brodsky<SUP>7</SUP>, Nobuhisa Eguchi<SUP>13</SUP>, Sean Toczko<SUP>13</SUP>, Expedition 343 and 343T Scientists?
Author Affiliations: <SUP>1</SUP>Center for Tectonophysics, Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843, USA. <SUP>2</SUP>Earth and Planetary Sciences Department, McGill University, Montreal, Canada. <SUP>3</SUP>Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan; Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan. <SUP>4</SUP>Department of Geosciences, Colorado State University, Fort Collins, CO 80523, USA. <SUP>5</SUP>Department of Geosciences, Pennsylvania State University, University Park, PA 16802, USA. <SUP>6</SUP>Dipartimento di Scienze della Terra, Universit? di Modena e Reggio Emilia largo, Modena, Italy. <SUP>7</SUP>Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, USA. <SUP>8</SUP>Department of Geology, University of Otago, Dunedin, New Zealand. <SUP>9</SUP>Center for Coastal and Ocean Mapping/Joint Hydrographic Center, University of New Hampshire, Durham, NH 03824, USA. <SUP>10</SUP>Department of Geology, University of Calcutta, Kolkata, India. <SUP>11</SUP>Department of Earth and Planetary Science, The University of Tokyo, Tokyo, Japan. <SUP>12</SUP>Earthquake Hazards Division, Disaster Prevention Research Institute, Kyoto University, Kyoto, Japan. <SUP>13</SUP>Center for Deep Earth Exploration, Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan.
*Corresponding author. E-mail: chesterf@tamu.edu
Abstract
The mechanics of great subduction earthquakes are influenced by the frictional properties, structure, and composition of the plate-boundary fault. We present observations of the structure and composition of the shallow source fault of the 2011 Tohoku-Oki earthquake and tsunami from boreholes drilled by the Integrated Ocean Drilling Program Expedition 343 and 343T. Logging-while-drilling and core-sample observations show a single major plate-boundary fault accommodated the large slip of the Tohoku-Oki earthquake rupture, as well as nearly all the cumulative interplate motion at the drill site. The localization of deformation onto a limited thickness (less than 5 meters) of pelagic clay is the defining characteristic of the shallow earthquake fault, suggesting that the pelagic clay may be a regionally important control on tsunamigenic earthquakes.
Deep Drilling for Earthquake Clues
The 2011 M<SUB>w</SUB> 9.0 Tohoku-Oki earthquake and tsunami were remarkable in many regards, including the rupturing of shallow trench sediments with huge associated slip (see the Perspective by Wang and Kinoshita). The Japan Trench Fast Drilling Project rapid response drilling expedition sought to sample and monitor the fault zone directly through a series of boreholes. Chester et al. (p. 1208) describe the structure and composition of the thin fault zone, which is predominately comprised of weak clay-rich sediments. Using these same fault-zone materials, Ujiie et al. (p. 1211) performed high-velocity frictional experiments to determine the physical controls on the large slip that occurred during the earthquake. Finally, Fulton et al. (p. 1214) measured in situ temperature anomalies across the fault zone for 9 months, establishing a baseline for frictional resistance and stress during and following the earthquake.
? Present address: Earth and Planetary System Science, Department of Natural History Sciences, Hokkaido University, N10 W8, Sapporo 060-0810, Japan.
? Expedition 343 and 343 T Scientists authors and affiliations are listed in Supplementary Materials.
Received for publication 24 July 2013.
Accepted for publication 30 October 2013.
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