IODP borehole observatories to monitor slow slip at the offshore Hikurangi subduction zone

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Author(s): Wallace, Laura M.; Solomon, Evan A.; Fulton, Patrick M.; Saffer, Demian M.; Petronotis, Katerina E.; Jannasch, Hans W.; Davis, Earl E.; Rhinehart, Bill; Van Hyfte, John; Grigar, Kevin; Barnes, Philip; Bell, Rebecca E.; Pecher, Ingo Andreas; LeVay, Leah J.
International Ocean Discovery Program, Expedition 372 Scientists
Author Affiliation(s): Primary:
University of Texas Austin, Institute for Geophysics, Austin, TX, United States
University of Washington, United States
Pennsylvania State University, United States
International Ocean Discovery Program, United States
Monterey Bay Aquarium Research Institute, United States
Pacific Geoscience Center, Canada
National Institute of Water & Atmospheric Research, New Zealand
Imperial College London, United Kingdom
University of Auckland, New Zealand
Volume Title: AGU 2018 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2018; American Geophysical Union 2018 fall meeting, Washington, DC, Dec. 10-14, 2018. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: The offshore northern Hikurangi subduction margin, New Zealand, is the site of some of the world's best-documented shallow slow slip events. Seafloor geodetic studies have suggested that SSEs there occur to within at least 2 km of the seafloor, and it is possible that they propagate all the way to the trench. IODP Expedition 375 recently completed installation of two subseafloor observatories at the offshore Hikurangi margin, aimed at monitoring slow slip event processes in the very near field. One of the observatories intersects a major active fault near the deformation front of the subduction zone. The fault zone observatory includes 3 levels of formation pressure monitoring (for volumetric strain), high-resolution temperature monitoring, and geochemical sampling and fluid flow monitoring within the fault zone. A second, simpler observatory was installed directly above the area of large slow slip on the offshore Hikurangi subduction zone, which involves two levels of formation pressure monitoring and high-resolution temperature monitoring. We will describe the installation of these observatories, and the types of instrumentation that was installed. We will discuss the scientific aims of the observatories, and the ability of the observatory configuration to resolve many outstanding questions about slow slip event processes. We will also address placement of the observatory monitoring intervals in the context of the coring and Logging-While-Drilling data that was acquired in advance of the observatory installation on Expeditions 372 and 375.
Year of Publication: 2018
Research Program: IODP2 International Ocean Discovery Program
Key Words: 16 Structural Geology; Active faults; Expedition 372; Expedition 375; Faults; Hikurangi Margin; International Ocean Discovery Program; Neotectonics; Pacific Ocean; Slip rates; South Pacific; Southwest Pacific; Subduction zones; Tectonics; West Pacific
Coordinates: S385830 S384330 E1790800 E1782830
S390300 S384100 E1791600 E1783500
Record ID: 2019050428
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