Project Leader:
Dr. Spahr Webb
Earth Institute Contact: Dr. Spahr Webb
Additional External Researchers:
Dan Frye, Robert Reves-Sohn - WHOI
Locations: Pacific Ocean
Special Locations:
Southern California Borderlands, Marmara Sea, the Aleutians Islands
Description:
The researchers propose to develop and test a mooring system for collecting real time, high bandwidth seismic information from the coastal ocean. The coastal region at active margins present a variety of fundamental scientific questions related to tectonics and earthquake mechanics whose study could be greatly advanced by the ability to extend seismic networks offshore. These regions (eg. Southern California Borderlands, Marmara Sea, the Aleutians Islands) also present very significant seismic and volcanic hazards that can be better monitored using offshore stations. The Real Time Offshore Seismic Station (RTOSS) consists of three elements: a buried seismometer with realtime output, a hardwired compliant connection from the seismometer to a surface buoy, and a solar powered RF telemetry link from the surface buoy to a shore station. LDEO will develop the seismic instrumentation and the deployment/burial mechanism for the sensor and the USGS will implement the data archiving and web-based data dissemination system. WHOI will develop the mooring system, RF telemetry system and lead the mooring operations field efforts. The key element in the mooring design is a 30-meter long compliant hose that connects the anchor to the vertical part of the mooring. This hose is capable of stretching to 2.4 times its unstretched length under normal mooring tensions giving the mooring the compliance it needs to respond to waves, tides and currents while maintaining tension in the mooring cable at all times. Electrical conductors are spiraled in the hose interior to transfer signals to the E/M mooring cable and then to the surface buoy. The seismometer, which is deployed some distance from the mooring anchor and connected to it by armored cable will be installed into the sediments to shield it from ocean currents and provide for better coupling to the ground. Full rate data from the seismometer will be sent to the surface via the mooring cables and compliant hose and telemetered to shore using an RF modem. The system will also collect seafloor pressure and pressure gradient data that will be used to suppress noise from ocean waves. Power for the sensor and RF link are generated by solar panels on the surface buoy. System development and prototype fabrication is scheduled for Year 1. During Year 2, a long term test of the system will be conducted at a site near Woods Hole (the buoy farm). In Year 3, we will operate the prototype near Kick'em Jenny, an underwater volcano with high levels of seismic activity located offshore of Grenada.
EI Unit:
Lamont-Doherty Earth Observatory (LDEO)
Cross Cutting Themes:
Hazards and Risk
Core Disciplines:
Earth Sciences
Collaborating Institutions:
Woods Hole Oceanographic Institution (WHOI)
Funding Agency:
National Science Foundation
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