EAGER:Field Testing Two New Portable Geothermal Gradient Probe Prototypes

Southern Methodist University, Dallas TX

Investigators

Abstract

For the past sixty years or so, scientists have been collecting heat flow data from the seafloor using large, heavy instruments that are inserted into the sediment and measure temperature versus depth below the seafloor. Heat flow data provide fundamental information on the physical, chemical and biological processes that are occurring near and below the seafloor and ultimately, information on the thermal and chemical evolution of Earth. The goal of this study is to advance the development of two prototype heat probes beyond the testing/development stage so that they can be used by the broad scientific community. The new heat-flow probes will be lighter and provide near-real-time temperature data; both of which will streamline how heat flow data currently are collected. The project incorporates new technology into the prototypes compared to conventional heat flow probes. The project includes international collaboration and provides training for an undergraduate student. This project aims to provide either real-time or near-real time temperature data at higher sample rates and with longer endurance time than standard heat flow probes. The prototypes have the potential to transform our understanding of complex submarine fluid flow near faults, seeps, vent sites, or caldera lakes. The two prototype probes are designed to operate in water depths of 500 m (Prototype-1) and 2000 m (Prototype-2); individual components for each probe have been pressure tested. Currently, however, the fully constructed probes are untested at pressures greater than 1 MPa (100 m water depth). Prototype-1 is designed to include real-time heat flow data and sea-bottom imaging for site characterization and selection; Prototype-2 is designed with Bluetooth data transmission. Both prototypes will increase heat flow data collection by a factor of two compared to conventional methods. Until pressure tests and geothermal gradient field tests are completed, however, the probes cannot be scheduled for scientific use without high risk of failure. This study has the potential to transform how marine heat flow and fluid fluxes are collected and analyzed, especially in high heat flow environments. Work involves full pressure testing and potential thermal gradient testing for prototype-2. Specifically, the pressure tests will go to 20 MPa (up to 2000 m water depth), and the thermistors will be tested offshore Montserrat. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.