OPP-99-06674 Sohn This is a collaborative project by Principal Investigators from Scripps Institution of Oceanography and Woods Hole Oceanographic Institution. The Principal Investigators will combine autonomous underwater vehicle (AUV) and ocean bottom seismometer (OBS) technologies to develop an instrument (AUVOBS) capable of making broadband seismic measurements on the seafloor beneath the Arctic Ocean ice cap. The structure of the instrument will be based on the Odyssey 11 AUV design and the seismometer package will be based on the "Webb" OBS developed by Spahr Webb at Scripps. These technologies will be integrated into a single instrument capable of being deployed and recovered from an icebreaker, and capable of making broadband seismic measurements over periods of up to one year on the seafloor.
The motivation for developing this instrument arises from the pressing need for seismic observations to constrain the nature of melt production in the mantle, crustal structure, and tectonism associated with the ultra-slow spreading Gakkel Ridge. The Gakkel Ridge is essentially unsampled because it lies beneath the Arctic Ocean permanent ice cap. This key piece of the global spreading system puzzle provides an opportunity to image crustal accretion and mantle processes that are masked or hidden in other spreading environments. The logistics and priorities for an international field program to study the Gakkel Ridge have been developed through a series of InterRidge workshops. One of the highest priorities is the acquisition of passive and active source seismic data. It has been impossible to make seismic measurements on the seafloor at the Gakkel Ridge, but with the development of an AUVOBS instrument, the Arctic Ocean Basin could be opened to seismic investigation. The Principal Investigators will solve the first order problems associated with deploying and recovering AUVs from icebreakers in the ice pack and modifying AUVs to make in situ seafloor measurements over long periods of time. In addition to developing an AUVOBS prototype, they will also develop techniques and hardware that will allow the routine deployment of AUVs for a variety of Arctic (and Antarctic) science missions in the future.
