High-Resolution Multibeam and Subbottom Surveys of Submarine Canyons, Deep-Sea Fan Channels, and Gas Seeps Using the MBARI Mapping AUV

The Monterey Bay Aquarium Research Institute (MBARI) has developed an autonomous seafloor mapping capability for high resolution mapping of the deep ocean seafloor. The MBARI Mapping AUV is a 21" diameter, Dorado class autonomous underwater vehicle (AUV) equipped with a 200 kHz multibeam sonar, 110 kHz and 410 kHz sidescan sonars, and a 2-16 kHz subbottom profiler. All components of the vehicle are rated to 6000 m depth. Using precise navigation and attitude data from an laser-ring-gyro-based inertial navigation system (INS) integrated with a Doppler velocity log sonar (DVL), the Mapping AUV can image the deep-ocean seafloor and shallow subsurface structure with much greater resolution than is possible with hull-mounted sonars. The system can also be operated in an ROV-mounted configuration, allowing near-bottom surveys in very restricted terrain. The Mapping AUV has conducted several autonomous surveys of Monterey Canyon and Smooth Ridge in Monterey Bay, and ROV-mounted surveys of five sites along the Monterey Canyon axis during 2005 and 2006. During June 2006, the Mapping AUV surveyed mounds and channel deposits in the Santa Monica Basin. The bathymetric surveys have achieved a vertical precision of 0.3 m; surveys from a 20 m altitude achieve sub-meter lateral resolution and surveys from 50-100 m altitudes achieve lateral resolutions less than 2 m. The subbottom profile data provides resolution of ~0.1 m with penetrations up to 50 m in soft sediments. The combination of high-resolution bathymetry with closely spaced subbottom profiles allow us to Additional Mapping AUV expeditions are planned for 2006, including surveys of Barclay submarine canyon and the summits of Davidson and Axial seamounts