IGPP is pleased to invite you to join its Winter 2023 Seminar Series presentation featuring University of Durham's Benjamin Idini. Dr. Idini's talk, "Turbidity currents: major new advances from directly measuring flows in action, and a rally call for more work in La Jolla Canyon?" will be available WEDNESDAY, March 1, 2023 via Zoom: https://ucsd.zoom.us/j/93116538488?pwd=dU1zRmd1bDljUHp6VCtYVW5yY3J5QT09 Password: igpp
Time: 12:00 pm, Pacific Time
Location: Revelle conference room and Zoom
Abstract: Turbidity currents form the largest sediment accumulations, deepest canyons, and longest channels on Earth, and one turbidity current can transport more sediment than the annual flux from all rivers. Turbidity currents break seabed cables that carry >99% of global data on which daily lives depend. They play a critical role in global organic carbon cycles that affects drawdown of atmospheric CO2 and global climate. They also transfer microplastic and other pollutants to the deep-sea, and may produce valuable long-term records of other major geohazards.
It was once thought by many that turbidity currents were almost impractical to measure in action, but turbidity currents have recently been measured in detail at ~10 sites worldwide. Detailed monitoring initially involved smaller flows in shallower water, in locations such as Canadian fjords and then Monterey Canyon. However, in 2020, a turbidity current was measured that accelerated from 5 to 8 m/s whilst travelling > 1,150 km offshore from the Congo River. This flow eroded ~2.65 km3 of sediment, equivalent to ~19-35% of global river sediment flux, which was flushed down one submarine canyon in a single year. The amount of terrestrial organic carbon carries by this turbidity current was comparable to the global annual flux buried in marine sediments. Excitingly, this flow was also remotely sensed using ocean bottom seismometers (OBS), potentially opening the way for remote sensing of turbidity currents, using instruments located outside the flow, and thus out of harm's way.
Direct monitoring is now leading to some major advances in understanding. Turbidity currents are more active than once thought and triggered in newly understood ways. They play a globally important role in organic carbon cycling, and new sensors show fast flows are driven by dense near-bed layers, and flows evolve in unexpected ways. Time-lapse surveys show how flows sculpt canyon and channels, including via fast-moving knickpoints, and how flow processes link to deposits. This presentation is a rally call both flow monitoring at a wider range of locations, using novel sensors, and emphasises how monitoring data must be combined with other approaches to tell the full story of turbidity currents.
Previous seminal work led by Scripps in La Jolla Canyon has indeed provided some of the more detailed information on turbidity currents. This talk thus also seeks to develop further flow monitoring and time lapse mapping efforts at this classic location.