Spatial and time variations in stress state in the Costa Rica subduction margin, IODP Expedition 334

Author(s): Yamamoto, Yuzuru; Lin, Weiren; Usui, Yoichi; Kanamatsu, Toshiya; Saito, Saneatsu; Zhao, Xixi; Hashimoto, Yoshitaka; Stipp, Michael; Ujiie, Kohtaro; Vannucchi, Paola
Integrated Ocean Drilling Program, Expedition 334 Scientific Party
Author Affiliation(s): Primary:
Japan Agency for Marine-Earth Science and Technology, Japan
University of California, United States
Kochi University, Japan
Leibniz-Institut für Meereswissenschaften, Germany
University of Tsukuba, Japan
University of Florence, Italy
Volume Title: 34th international geological congress; abstracts
Source: International Geological Congress [International Geological Congress, Abstracts = Congrès Géologique International, Résumés, Vol.34, p.304; 34th international geological congress, Brisbane, Queensl., Australia, Aug. 5-10, 2012. Publisher:], [location varies], International CODEN: IGABBY
Note: In English. Accessed on June 17, 2014
Summary: The Costa Rica Seismogenesis Project (CRISP) is designed to understand the processes that control nucleation and seismic rupture of large earthquakes at erosional subduction zones. Integrated Ocean Drilling Program (IODP) Expedition 334 drilled and cored at the middle slope (Sites U1378 and U1380), upper slope (Site U1379), and input site (Site U1381). Stress and strain analyses using anelastic strain recovery (ASR), fault kinematics, and anisotropy of magnetic susceptibility (AMS) have been conducted in the middle and the upper slope. Based on ASR analyses, clear difference in present-days stress state between the slope sediments and the basement was identified in the Site U1379: A normal-fault stress regime characterizes the slope sediments, whereas a strike-slip regime corresponds to the basement. On the other hand, the stress-states in the slope sediments in the Sites U1378 and U1380 are characterized by a strike-slip regime that σ2 has oriented vertically. The σ1 direction oriented NNW-SSE, which is corresponding to the σHmax direction identified in the LWD, parallel to the present GPS direction. In contrast to the present-day stress state, the ancient stress and strain based on kinematics of faults and AMS were controlled by direction of plate subduction. The spatial and time variations in stress state along the CRISP transect is a key to examining the onset of subduction erosion along the subduction channel.
Year of Publication: 2012
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 19 Geophysics, Seismology; Basement; Central America; Costa Rica; Costa Rica Seismogenesis Project; Earthquakes; East Pacific; Expedition 334; Faults; IODP Site U1378; IODP Site U1379; IODP Site U1380; IODP Site U1381; Integrated Ocean Drilling Program; Magnetic susceptibility; Normal faults; North Pacific; Northeast Pacific; Pacific Ocean; Plate tectonics; Seismicity; Spatial variations; Strain; Stress fields; Strike-slip faults; Subduction; Subduction zones; Temporal distribution
Coordinates: N083532 N083532 W0840438 W0840438
N083600 N083600 W0840424 W0840424
Record ID: 2014083198
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