A Real-time, Borehole, Geophysical Observatory Above The Cascadia Subduction Zone
Abstract
In July 2016, a team from WHOI and RSMAS installed a suite of seismic, geodetic and geothermal sensors in IODP borehole U1364A on the Cascadia Accretionary Prism offshore Vancouver Island. The borehole observatory was connected to the Clayoquot Slope node of the Ocean Networks Canada NEPTUNE Observatory in June 2017. The 3 km long extension cable provides power, timing, and internet connectivity. The borehole sits 4 km above the subduction zone thrust interface, and when drilled in 2010 was instrumented with an ACORK (Advanced Circulation Obviation Retrofit Kit) that allows monitoring and sampling of fluids from multiple zones within the 330 m drilled formation. The borehole ground-motion sensors consist of a broadband seismometer and two geodetic-quality (nano-radian resolution) two-axis tilt sensors clamped to the borehole casing wall at a depth of 277 m below the seafloor. The tilt sensors were selected to detect non-seismic, strain-related transients. A 24-thermistor cable extends from the seafloor to just above the seismometer and tilt-sensor package. The seismic and geodetic data have been flowing from the observatory (network code NV, station code CQS64, location codes B1, B2, and B3) since June and are available from the IRIS DMC. Initial inspection of the seismic and geodetic data shows that all sensors are operating well. We will report on station performance and detection thresholds using an anticipated 5 month duration data set.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.T51E0523C
- Keywords:
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- 1209 Tectonic deformation;
- GEODESY AND GRAVITY;
- 3006 Marine electromagnetics;
- MARINE GEOLOGY AND GEOPHYSICS;
- 3050 Ocean observatories and experiments;
- MARINE GEOLOGY AND GEOPHYSICS;
- 8170 Subduction zone processes;
- TECTONOPHYSICS