Seagoing Instrumentation
	Mike Tryon, Alison LaBonte, and Kevin Brown Scripps Institution of Oceanography, UCSD

We have developed instrumentation for sampling fluid and measuring flow rate through the sediment-water interface at the seafloor. This general class of instrumentation, has applications in the geodynamic, geochemical, biogeochemical and hydrologic fields. Recent studies with this instrumentation enabled us to understand hydrogeologic issues associated with unstable and transient flow around methane hydrates and gas seeps, and to discover regional hydrotectonic events that appear to be associated with plate boundary creep events (ultra-slow earthquakes). Improved geodynamic observations are being made with the new electronic instrumentation and associated methodologies are being developed for real-time observation in the hunt for slow earthquakes in subduction zones.

1) The Chemical and Aqueous Transport meter program utilizes osmotically driven seafloor instrumentation to determine the flux rates of fluids and associated dissolved chemical components through the sea floor. These relatively inexpensive instruments are also used in the study of transient processes relating to longer-term tectonic and hydrologic instabilities. Their geochemical sampling abilities have recently been extended to simultaneously collect both pressurized gas and aqueous samples.

2) The Optical Tracer Injection System was developed to monitor higher flow rates and has the ability to investigate the relationship between fluid flow and tectonics, i.e. transient events, at a higher level of temporal resolution that the CAT meters. As an electronically based system, the OTIS meter is equipped for real time data acquisition through satellite or cable linkup.

3) We also deploy commercially available ocean going instrumentation in conjuntion with CAT and OTIS meters such as: temperature and pressure sensors current meters acoustic release systems

Images from our seagoing programs