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doi:10.2204/iodp.proc.343343T.101.2013 Scientific objectives and operational strategyThe main goal of Expedition 343 is to understand the stress conditions and physical characteristics of the fault that allow very large slip to occur near the trench. The following specific science objectives reflect the unique possibilities provided by rapid response drilling into a fault following a large earthquake. The shallow distribution of large slip for the Tohoku-oki earthquake provides an unprecedented opportunity to directly access a fault that has recently moved tens of meters. As outlined in the report from the International Continental Scientific Drilling Program/Southern California Earthquake Center international workshop on rapid response drilling (Brodsky et al., 2009), fundamental questions regarding stress, faulting-related fluid flow, and the structural and mechanical characteristics of the earthquake rupture zone can be addressed uniquely through rapid response drilling. The science questions and strategies for addressing them are as follows:
Secondary science objectives include carrying out other geological, geochemical, and microbiological observations to the greatest extent possible during drilling in accordance with the IODP Measurements guidelines (www.iodp.org/program-policies/). As a specific example, there is some evidence that great amounts of hydrogen may be released at the time of large faulting (e.g., Kita et al., 1982). The production of hydrogen may stimulate microbiological activity; thus, samples of the fault may contain records of biogeochemical and microbiological processes. The primary science objectives are closely aligned with the Initiative: Seismogenic Zone of the IODP Initial Science Plan. This initiative advocates subduction zone studies that include investigating the behavior of rocks and sediments to better understand the fault zone and integration with studies of earthquake mechanics. Furthermore, this project directly addresses Challenge 12 of the IODP Science Plan for 2013–2023: “What mechanisms control the occurrence of destructive earthquakes, landslides, and tsunami?” |