| Title | Foundational experiences and recent advances in long-term deep-ocean borehole observatories for hydrologic, geodetic, and seismic monitoring |
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| Author | Davis, E ; Becker,
K; Kyo, M; Kimura, T |
| Source | State of technology report 2018; Marine Technology Society, Journal vol. 52, no. 5, 2018 p. 74-86, https://doi.org/10.4031/MTSJ.52.5.4 |
| Image |  |
| Year | 2018 |
| Alt Series | Natural Resources Canada, Contribution Series 20190032 |
| Publisher | Marine Technology Society |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf (Adobe® Reader®) |
| Province | British Columbia; Western offshore region |
| NTS | 92B; 92C; 92E; 92F; 92G |
| Area | Vancouver Island; Washington State; Olympic Peninsula; Cape Murto; Kii Peninsula; Canada; United States of America; Japan |
| Lat/Long WENS | -131.0000 -122.0000 49.5000 47.0000 |
| Lat/Long WENS | 133.0000 138.0000 33.6667 32.0000 |
| Subjects | marine geology; tectonics; geophysics; hydrogeology; marine environments; deep sea drilling; cores, deepwater; boreholes; crustal studies; tectonic environments; tectonic interpretations; geodynamics;
geodesy; crustal movements; crustal structure; crustal evolution; oceanic crust; plate margins; subduction zones; sea floor spreading; mid-ocean ridges; deformation; seismic surveys; seismic interpretations; seismic data; seismic velocities;
seismology; hydrologic environment; hydrologic properties; permeability; drainage; history; in-field instrumentation; field methods; temperature; pressure; tectonic history; Cascadia Subduction Zone; Juan de Fuca Ridge; Nootka Fault; Nankai
Subduction Zone; Ocean Drilling Program (ODP); Integrated Ocean Drilling Program (IODP); Costa Rica Subduction Zone |
| Illustrations | schematic diagrams; geoscientific sketch maps; time series; spectra; plots; profiles |
| Program | Public Safety Geoscience Assessing Earthquake Geohazards |
| Program | Ocean Drilling Program |
| Program | Integrated Ocean Drilling Program |
| Released | 2018 09 01 |
| Abstract | For nearly three decades, various phases of the scientific Ocean Drilling Programs have deployed sealed-hole observatories in deep-ocean boreholes for long-term subseafloor monitoring to address a range
of hydrologic and geodynamic objectives. We summarize the scientific motivation for these observatories and review some important early results from those installed in young oceanic crust and subduction zones. We also summarize the evolution of the
borehole observatory designs and associated instrumentation, from simple single-interval installations with autonomous low-rate temperature and pressure monitoring to recent multiple-zone installations with sophisticated downhole instrument packages
connected to seafloor cabled networks that provide power and high-rate, real-time data access. We emphasize recent advances, illustrated with example data drawn mainly from transects of borehole observatories offshore Japan and Cascadia. These
examples illustrate the value of borehole observatory data in resolving a wide range of crustal geodynamic responses from long periods of gradual geodetic change and accumulation of stress to episodes of rapid deformation associated with both
seafloor spreading and subduction processes. |
| Summary | (Plain Language Summary, not published)
CORK borehole observatories were first developed by the first two authors to determine the thermal and pressure state of hydrothermal systems in the
oceanic crust. Since the first installation in 1991 (Davis et al., 1992), a total of 32 DSDP/ODP/IODP holes have been completed and instrumented for a wide range of objectives that involve geochemical and microbiological sampling long after drilling
perturbations have dissipated, and seismological and geodynamic measurements that help constrain aspects of both slow and seismogenic slip on local or distant faults. Several of these CORK observatories have been connected to fibre-optic cable
systems off Japan and Canada; the most recent installations were completed in the Hikurangi subduction zone off New Zealand; new installations are being planned for the Cascadia subduction zone as part of a comprehensive study of geodynamics of the
Juan de Fuca plate and its boundaries. |
| GEOSCAN ID | 314627 |
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