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Preconditioning by sediment accumulation can produce powerful turbidity currents without major external triggers

Bailey, Lewis P.; Clare, Michael A.; Rosenberger, Kurt J.; Cartigny, Matthieu J.B.; Talling, Peter J.; Paull, Charles K.; Gwiazda, Roberto; Parsons, Daniel R.; Simmons, Stephen M.; Xu, Jingping; Haigh, Ivan D.; Maier, Katherine L.; McGann, Mary; Lundsten, Eve; Monterey CCE Team

Authors

Lewis P. Bailey

Michael A. Clare

Kurt J. Rosenberger

Matthieu J.B. Cartigny

Peter J. Talling

Charles K. Paull

Roberto Gwiazda

Jingping Xu

Ivan D. Haigh

Katherine L. Maier

Mary McGann

Eve Lundsten

Monterey CCE Team



Abstract

Turbidity currents dominate sediment transfer into the deep ocean, and can damage critical seabed infrastructure. It is commonly inferred that powerful turbidity currents are triggered by major external events, such as storms, river floods, or earthquakes. However, basic models for turbidity current triggering remain poorly tested, with few studies accurately recording precise flow timing. Here, we analyse the most detailed series of measurements yet made of powerful (up to 7.2 m s−1) turbidity currents, within Monterey Canyon, offshore California. During 18-months of instrument deployment, fourteen turbidity currents were directly monitored. No consistent triggering mechanism was observed, though flows did cluster around enhanced seasonal sediment supply. We compare turbidity current timing at Monterey Canyon (a sandy canyon-head fed by longshore drift) to the only other systems where numerous (>10-100) flows have been measured precisely via direct monitoring; the Squamish Delta (a sandy fjord-head delta), and the Congo Canyon (connected to the mud-dominated mouth of the Congo River). A common seasonal pattern emerges, leading to a new model for preconditioning and triggering of turbidity currents initiating through slope failure in areas of sediment accumulation, such as canyon heads or river mouths. In this model, rapid or sustained sediment supply alone can produce elevated pore pressures, which may persist, thereby predisposing slopes to fail. Once preconditioned, a range of minor external perturbations, such as moderate storm-waves, result in local pore pressure variation, and thus become effective triggers. Major external triggers are therefore not always a prerequisite for triggering of powerful turbidity currents.

Citation

Bailey, L. P., Clare, M. A., Rosenberger, K. J., Cartigny, M. J., Talling, P. J., Paull, C. K., …Monterey CCE Team, . (2021). Preconditioning by sediment accumulation can produce powerful turbidity currents without major external triggers. Earth and planetary science letters, 562, https://doi.org/10.1016/j.epsl.2021.116845

Journal Article Type Article
Acceptance Date Feb 17, 2021
Online Publication Date Mar 3, 2021
Publication Date May 15, 2021
Deposit Date Mar 9, 2021
Publicly Available Date Mar 4, 2022
Journal Earth and Planetary Science Letters
Print ISSN 0012-821X
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 562
Article Number 116845
DOI https://doi.org/10.1016/j.epsl.2021.116845
Keywords Submarine canyon; Turbidity current; Geohazard; Direct monitoring; Preconditioning; Triggering
Public URL https://hull-repository.worktribe.com/output/3738131
Additional Information This article is maintained by: Elsevier; Article Title: Preconditioning by sediment accumulation can produce powerful turbidity currents without major external triggers; Journal Title: Earth and Planetary Science Letters; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.epsl.2021.116845; Content Type: article; Copyright: © 2021 Published by Elsevier B.V.