This RAPID proposal seeks funding to develop, build and deploy a proto-type full ocean depth Ocean Bottom Seismograph (OBS) in the Mariana Trench in January 2013. Current OBSs are limited to deployment depths of 5000-6000m, and the few experiments that have deployed at or near those depths have had poorer instrument and data return rates. The scientific need for full ocean depth instruments is increasingly being recognized with recent large tsunamigenic subduction zone earthquakes, as well as broader interest in full global coverage of seismic monitoring for understanding deep earth processes.
The PIs have been offered the opportunity to utilize full-ocean depth technology developed for the recent manned dive by James Cameron to Challenger Deep in the Mariana Trench. In addition, a cruise of opportunity exists in January 2013, in which the instrument will be deployed at about 8600 m and collect approximately a week of seismic data at depth.
Broader Impacts:
This development project has the long term potential for using full ocean depth OBSs to monitor and perhaps forecast areas at risk for large destructive submarine earthquakes. Large submarine earthquakes in the last decade alone have taken hundreds of thousands of lives globally, cost hundreds of billions of dollars and resulted in catastrophic environmental damage such as the Fukushima nuclear power plant disaster.
We have developed a prototype full ocean depth ocean bottom seismometer that was tested in the Mariana Trench in February 2013. We demonstrated that the components of the full ocean depth ocean bottom seismometer worked at ~8000m (the deepest available site during the cruise of opportunity). The deployment demonstrated not only the reliability of the major components at depth, but also that we met our design criteria to have the instrument ascend and descend more rapidly than regular OBSs – a twofold improvement on existing LDEO designs. Additionally, our design proved the viability of a low cost, reliable seafloor seismometer, utilizing significantly lower cost sensors, single chip data loggers, and rechargeable conventional batteries rather than expensive one-time use lithium batteries. The project took advantage of technology transfer from James Cameron’s historic dive to the Mariana Trench. Collaborating with his engineering team, we were able to utilize their unique syntactic foam design for full ocean depth. This instrument if developed beyond the prototype has the potential to make critical geophysical measurements at deep subduction zones where many of the devastating tsunamis are generated. Many of the critically locked sections of these subduction zone faults make up the deepest sections of our global oceans. Present day instrument fleets are not designed to reach these depths, but this project demonstrates a low-cost, viable option. See for instance, TedX talk by M. Tolstoy: http://tedxtalks.ted.com/video/Seafloor-Earthquakes-Maya-Tolst
