HR: 0800h
AN: OS41D-0510    [Abstracts]
TI: In-Situ Measurements of Turbidity Currents in Monterey Submarine Canyon
AU: * Xu, J
EM: jpx@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Rd., Menlo Park, CA 94025 United States
AU: Noble, M
EM: mnoble@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Rd., Menlo Park, CA 94025 United States
AU: Rosenfeld, L
EM: lkrosenf@nps.navy.mil
AF: Naval Postgraduate School, 833 Dyer Rd, Monterey, CA 93943 United States
AB: Turbidity currents are thought to be the main mechanism to move ~500,000 m${^3}$ of sediments annually from the head of the Monterey submarine canyon to the deep-sea fan. Indirect evidence has shown frequent occurrences of such turbidity currents in the canyon, but the dynamic properties of the turbidity currents such as maximum speed, duration, and dimensions are still unknown. Here we present the first-ever in-situ measurements of velocity profiles and sediment transport of four distinct turbidity currents observed during a year-long deployment of three deep-sea moorings December 2002 - November 2003. Each turbidity current started abruptly and gradually dissipated within 5 - 8 hours. The body of the turbidity currents, whose maximum along-canyon velocity reached 190 cm/s, were mostly confined to the bottom 50 m of water, but the turbid cloud that followed occluded instruments as much as 170 m above the canyon floor. Triggering mechanisms of these turbidity currents will also be discussed.
DE: 4558 Sediment transport
DE: 4594 Instruments and techniques
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting