Field Activity Details for field activity Z107MB

AKA: none

Other ID: Z-1-07-MB,MBARI ID 295

Status: Completed

Organization(s): USGS, Pacific Coastal and Marine Science Center

Funding Program(s):

Principal Investigator(s):

Affiliate Investigator(s): David Caress (MBARI)

Information Specialist(s): Bill Normark

Data Type(s): Location-Elevation: Navigation, Seismics: Boomer, Sonar: Multibeam

Scientific Purpose/Goals: Three AUV dives were planned in the Little Lucia channel system, located offshore between Point Sur, CA and the offshore Santa Maria Basin. The primary target was the transition from highly channelized to unconfined sedimentation features. The areas mapped are in water depths of 975 to 1050 m. The primary objective of these dives is to obtain multibeam bathymetric data and subbottom profiles. Processing and analysis of this data will be used to study the sedimentary architecture of the area. Approximately 1.5-m-long vibracores were taken using the MBARI ROV Tiburon during cruise W-4-06-MB.

Vehicle(s):

Start Port/Location: Moss Landing

End Port/Location: Moss Landing

Start Date: 2007-03-12

End Date: 2007-03-14

Equipment Used: multibeam, GPS, Chirp

Information to be Derived: Very high-resolution bathymetry and subbottom structure of the Little Lucia channel and lobe system. Bathymetric maps are produced at a one-meter contour interval.

Summary of Activity and Data Gathered: ~1600/JD071 R/V Zephyr departs Moss Landing. ~1411/JD072 Begin first successful AUV dive over Little Lucia ~2311/JD072 Complete first successful AUV Dive over Little Lucia ~1000/JD073 R/V Zephyr arrives in Moss Landing A total of 2 AUV dives were completed. The first dive was unsuccessful because problems with the acoustic modem prevented accurate tracking of the AUVs location. Releasing the AUVs drop weight failed to cause the AUV to abort the dive, but the data collected cannot be used for analysis. A second dive covered the same area planned for the first dive and successfully collected multibeam bathymetry and subbottom data. The AUVs starting position was determined by GPS at the launch site. The vehicle then dives in a USBL-nav-aided spiral to 50 meters above the seafloor. The total survey trackline was 42.5 km with 150 m line spacing. The AUV can survey with the multibeam sounding system and chirp sonar for ~9 hours; it then returns to the sea surface to be picked by the R/V Zephyr. Only one-third of the objectives of the cruise were attained because of weather. A second cruise is planned to complete the two additional dives.

Staff:

Affiliate Staff:
Katie Maier (Stanford) - Scientist
Hans Thomas (MBARI) - AUV operations
Duane Thompson (MBARI) - AUV operations
Aaron Gregg (Master

MBARI) - Zephyr crew
Matthew Noyes (Engineer

MBARI) - Zephyr crew
Paul Ban (Mate

MBARI) - Zephyr crew
Perry Shoemake (Mate

MBARI) - Zephyr crew

Notes: Used seafloor mapping AUV; MBARIs automated underwater vehicle (AUV) for sea-floor mapping and subbottom profiles. The AUV has a high-resolution Edgetech chirp sonar profiling system and a multibeam sounding system and uses both Doppler sonar tracking of the sea floor and an inertial guidance system for position control. The AUV descends to 50 m above the seafloor with USBL-nav-aided spiral descent. Organization listed Chevron Energy Technology Company; changed to Chevron

Location:

Little Lucia Canyon and lobe area

Platform(s):

Publications

Portals/Viewers

Data Acquired