Collaborative Research: A Real-Time Nearshore Seafloor Seismic Station

Proposal Title: Collaborative Research: A Real-Time Nearshore Seafloor Seismic Station

Funds are requested to develop and test a mooring system to collect real time, high bandwidth seismic information from the coastal ocean, which at active margins presents a variety of fundamental scientific questions related to tectonics and earthquake mechanics. This region is also characterized by seismic and volcanic hazards that can be better monitored using offshore stations. The proposed Real Time Offshore Seismic Station (RTOSS) consists of three elements: a buried seismometer with real-time 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 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 capability to respond to waves, tides and currents while maintaining tension in the mooring cable. 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 damage 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 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 mooring will be deployed in Year 3, and operated near Kick'em Jenny, an underwater volcano with high levels of seismic activity located offshore of Grenada.