Multidisciplinary Observatory Development in Monterey Bay

Institute has several ongoing, parallel development efforts that have a common goal of providing long-term multi-sensor measurements of ground motion and fluid flow on the seafloor. Instrument packages are being designed to operate in a low-power, autonomous mode, but a planned logger/controller will provide Ethernet connection to available cables to either a shore-based laboratory or a telemetered mooring. We describe here instrument deployments that have taken place in the last four years (corehole and broadband seismometers and chemical sensors) as well as plans for the immediate future. Corehole seismometers Seismometer development was initiated at MBARI in 1996 with the development of a short-period corehole seismometer, designed and fabricated by the JPL Microdevice laboratory (Stakes et al., 1998). This sensor package uses three standard 4.5-Hz geophones with an extended flat response to about 0.8 Hz. The sensor package is placed into 2.5 inch diameter boreholes drilled into basement outcrops to provide superior coupling and greatly reduced noise. A new low-power datalogger, the GeoSense LP1, developed in 1997, can provide more than 24 GB of storage using less than 0.3 watt of power, easily supporting a 12-month deployment