IODP Expedition 362; initial results from drilling the Sumatra subduction zone; the role of input materials in shallow seismogenic slip and forearc plateau development

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Author(s): McNeill, Lisa Claire; Dugan, Brandon; Petronotis, Katerina E.
International Ocean Discovery Program (IODP), Expedition 362 Scientists, College Station, TX
Author Affiliation(s): Primary:
University of Southampton, Ocean and Earth Science, Southampton, United Kingdom
Colorado School of Mines, United States
Texas A&M University, United States
Volume Title: AGU 2016 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2016; American Geophysical Union 2016 fall meeting, San Francisco, CA, Dec. 12-16, 2016. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: IODP Expedition 362, August-October, 2016, plans to drill two boreholes within the input section of the Indian oceanic plate entering the North Sumatran subduction zone. In 2004, a Mw 9.2 earthquake ruptured the Sunda subduction zone from North Sumatra to the Andaman Islands, a length of ∼1500 km. The earthquake and tsunami devastated coastal communities around the Indian Ocean. This earthquake and the 2011 Tohoku-Oki Mw 9.0 earthquake showed unexpectedly shallow megathrust slip. In the case of North Sumatra, this shallow slip was focused beneath a distinctive plateau of the accretionary prism. This intriguing seismogenic behavior and forearc structure are not explained by existing models or by observations at other margins where seismogenic slip typically occurs farther landward. Expedition 362 will use core and log data in conjunction with in situ temperature and pressure measurements to document the lithology, structures, and physical and chemical properties of the input sediments. The input materials of the North Sumatran subduction zone are a distinctive, thick (up to 4-5 km) sequence of primarily Bengal-Nicobar Fan-related sediments. This sequence geophysically shows strong evidence for induration and dewatering and has probably reached the temperatures required for sediment-strengthening diagenetic reactions, and input materials may be key to driving the distinctive slip behavior and long-term forearc structure. The plate boundary fault (décollement) originates within the lower pelagic and submarine fan sediments so sampling this interval will help determine what controls décollement development and how its properties evolve. Initial results from the Expedition and plans for post-expedition experiments and modeling will be presented. These methods will be used to predict physical, thermal, fluid, and mechanical properties and diagenetic evolution of the sediments as stresses and temperatures increase due to burial and subduction. Results will be used to test the role of sediment properties in shallow earthquake slip and in the unusual forearc structure. In addition, the results will contribute to our understanding of a) Bengal-Nicobar fan history and records of Himalayan uplift, erosion and monsoon development, and b) stress conditions in a complexly deforming region of the Indian plate.
Year of Publication: 2016
Research Program: IODP2 International Ocean Discovery Program
Key Words: 07 Marine Geology and Oceanography; Asia; Cores; Drilling; Earthquakes; Expedition 362; Far East; Indonesia; International Ocean Discovery Program; Marine sediments; Sediments; Seismotectonics; Slip rates; Sumatra; Sumatra-Andaman Islands earthquake 2004; Tectonics; Tsunamis
Record ID: 2017056129
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by, and/or abstract, Copyright, American Geophysical Union, Washington, DC, United States

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