Flood-triggered versus earthquake-triggered turbidites: A sedimentological study in clastic lake sediments (Eklutna Lake, Alaska)

Elke Vandekerkhove; Maarten Van Daele; Nore Praet; Veerle Cnudde; Peter J. Haeussler; Marc De Batist

doi:10.1111/sed.12646

Flood-triggered versus earthquake-triggered turbidites: A sedimentological study in clastic lake sediments (Eklutna Lake, Alaska)

Elke Vandekerkhove^*, Maarten Van Daele, Nore Praet, Veerle Cnudde, Peter J. Haeussler, Marc De Batist

^*Corresponding author for this work

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

Lake sediments in Eklutna Lake, Alaska, reveal the presence of turbidites within varved sequences. These turbidites, which result from flood events and earthquakes, show a similar macroscopic appearance. In order to use turbidites to reconstruct flood variability and/or seismic history in the lake basin, it is crucial to determine the trigger of the turbidity currents. This study examined the turbidite caused by the ad 1964 Great Alaska earthquake as well as turbidites linked to historical flood events in order to differentiate between these earthquake-triggered and flood-triggered turbidites. In a suite of samples from throughout the lake, distinctive proxies are identified that can be associated with event-specific flow characteristics. The study presents straightforward discrimination methods related to the sedimentology and geochemical components of the turbidites. These methods are also applicable to other lakes, particularly proglacial lakes where the sediment composition of onshore and offshore sources is similar. Finally, the discrimination of the turbidite trigger can be used to reconstruct the palaeoflood and seismic history.

Original language	English
Pages (from-to)	364-389
Number of pages	26
Journal	Sedimentology
Volume	67
Issue number	1
DOIs	https://doi.org/10.1111/sed.12646
Publication status	Published - Jan 2020
Externally published	Yes

Funding

This research was funded by the Research Foundation ? Flanders (FWO). We would like to thank Koen De Rycker and Dr Philipp Kempf for their assistance on the field. We thank Dr Rik Achten for the use of the medical CT scanner at Ghent University Hospital and the UGent expertise centrum for X-ray Tomography (UGCT). Finally, we are grateful to Bruno Wilhelm, SeanPeal LaSalle (USGS) and an anonymous reviewer for the constructive comments, improving an earlier version of this paper. This research used data acquired at the XRF Core Scanner Laboratory at the MARUM ? Center for Marine Environmental Sciences, University of Bremen, Germany.

Keywords

Alaska
earthquake
flooding
lacustrine palaeoseismology
palaeoflood hydrology
turbidites
X-ray CT

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title = "Flood-triggered versus earthquake-triggered turbidites: A sedimentological study in clastic lake sediments (Eklutna Lake, Alaska)",

abstract = "Lake sediments in Eklutna Lake, Alaska, reveal the presence of turbidites within varved sequences. These turbidites, which result from flood events and earthquakes, show a similar macroscopic appearance. In order to use turbidites to reconstruct flood variability and/or seismic history in the lake basin, it is crucial to determine the trigger of the turbidity currents. This study examined the turbidite caused by the ad 1964 Great Alaska earthquake as well as turbidites linked to historical flood events in order to differentiate between these earthquake-triggered and flood-triggered turbidites. In a suite of samples from throughout the lake, distinctive proxies are identified that can be associated with event-specific flow characteristics. The study presents straightforward discrimination methods related to the sedimentology and geochemical components of the turbidites. These methods are also applicable to other lakes, particularly proglacial lakes where the sediment composition of onshore and offshore sources is similar. Finally, the discrimination of the turbidite trigger can be used to reconstruct the palaeoflood and seismic history.",

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AU - Haeussler, Peter J.

AU - De Batist, Marc

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N2 - Lake sediments in Eklutna Lake, Alaska, reveal the presence of turbidites within varved sequences. These turbidites, which result from flood events and earthquakes, show a similar macroscopic appearance. In order to use turbidites to reconstruct flood variability and/or seismic history in the lake basin, it is crucial to determine the trigger of the turbidity currents. This study examined the turbidite caused by the ad 1964 Great Alaska earthquake as well as turbidites linked to historical flood events in order to differentiate between these earthquake-triggered and flood-triggered turbidites. In a suite of samples from throughout the lake, distinctive proxies are identified that can be associated with event-specific flow characteristics. The study presents straightforward discrimination methods related to the sedimentology and geochemical components of the turbidites. These methods are also applicable to other lakes, particularly proglacial lakes where the sediment composition of onshore and offshore sources is similar. Finally, the discrimination of the turbidite trigger can be used to reconstruct the palaeoflood and seismic history.

AB - Lake sediments in Eklutna Lake, Alaska, reveal the presence of turbidites within varved sequences. These turbidites, which result from flood events and earthquakes, show a similar macroscopic appearance. In order to use turbidites to reconstruct flood variability and/or seismic history in the lake basin, it is crucial to determine the trigger of the turbidity currents. This study examined the turbidite caused by the ad 1964 Great Alaska earthquake as well as turbidites linked to historical flood events in order to differentiate between these earthquake-triggered and flood-triggered turbidites. In a suite of samples from throughout the lake, distinctive proxies are identified that can be associated with event-specific flow characteristics. The study presents straightforward discrimination methods related to the sedimentology and geochemical components of the turbidites. These methods are also applicable to other lakes, particularly proglacial lakes where the sediment composition of onshore and offshore sources is similar. Finally, the discrimination of the turbidite trigger can be used to reconstruct the palaeoflood and seismic history.

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KW - flooding

KW - lacustrine palaeoseismology

KW - palaeoflood hydrology

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KW - X-ray CT

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Flood-triggered versus earthquake-triggered turbidites: A sedimentological study in clastic lake sediments (Eklutna Lake, Alaska)

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