| Institution: | 1. Renard Centre of Marine Geology, Department of Geology, Ghent University, Krijgslaan 281 S8, 9000 Gent, Belgium;2. Renard Centre of Marine Geology, Department of Geology, Ghent University, Krijgslaan 281 S8, 9000 Gent, Belgium
MARUM, University of Bremen, Leobener Strasse 8, 28359 Bremen, Germany;3. Centre of X-ray Tomography-PProGRess, Department of Geology, Ghent University, Krijgslaan 281 S8, 9000 Gent, Belgium;4. USGS – Alaska Science Center, 4210 University Dr, Anchorage, AK, USA |
| 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. |
