Reconstructing 4000 years of mass movement and tsunami history in a deep peri‐Alpine lake (Lake Geneva, France‐Switzerland)

Abstract

The study of mass movements in lake sediments provides insights into past natural hazards at historic and prehistoric timescales. Sediments from the deep basin of Lake Geneva reveal a succession of six large-scale (volumes of 22 x 10^6 to 250 x 10^6 m^3) mass-transport deposits, associated with five mass movement events within 2600 years (4000 cal BP to 563 AD). The mass-transport deposits result from: (i) lateral slope failures (mass-transport deposit B at 3895 ± 225 cal BP and mass-transport deposits A and C at 3683 ± 128 cal BP); and (ii) Rhône delta collapses (mass-transport deposits D to G dated at 2650 ± 150 cal BP, 2185 ± 85 cal BP, 1920 ± 120 cal BP and 563 AD, respectively). Mass-transport deposits A and C were most probably triggered by an earthquake, whereas the Rhône delta collapses were likely to be due to sediment overload with a rockfall as the external trigger (mass-transport deposit G, the Tauredunum event in 563 AD known from historical records), an earthquake(mass-transport deposit E) or unknown external triggers (mass-transport deposits D and F). Independent of their origin and trigger mechanisms, numerical simulations show that all of these recorded mass-transport deposits are large enough to have generated at least metre-scale tsunamis during mass movement initiation. Since the Tauredunum event in 563 AD, two small-scale (volumes of 1 to 2x10^6 m^3) mass-transport deposits (H and I) are present in the seismic record, both of which are associated with small lateral slope failures. Mass-transport deposits H and I might be related to earthquakes in Lausanne/Geneva (possibly) 1322 AD and Aigle 1584 AD, respectively. The sedimentary record of the deep basin of Lake Geneva, in combination with the historical record, show that during the past 3695 years, at least six tsunamis were generated by mass movements, indicating that the tsunami hazard in the Lake Geneva region should not be neglected, although such events are not frequent with a recurrence time of 0.0016 yr-1

Sediment dynamics in paired High Arctic lakes revealed from high‐resolution swath bathymetry and acoustic stratigraphy surveys

“…Known turbidite thickness in East Lake (millimeter scale) and the runoff of the river which attains peaks of 1–2 m 3 /s during snowmelt (peak discharge) also suggest that the hyperpycnal flows are rather dilute. These low‐energy hyperpycnal flows are not erosive enough to produce large canyon‐channel systems that can concentrate flows downslope [e.g., Kremer et al ., , ; Normandeau et al ., ]. Instead, the flows being triggered at the delta front remain largely unconfined.…”

The role of mass-transport deposits and turbidites in shaping modern lacustrine deepwater channels

“…The various types of MTDs that were described in the sedimentary record of the distal basin of Lake Geneva significantly contributed to the sediment budget of the deep lake basin with volumes ranging from 22 Â 10 6 to 250 Â 10 6 m 3 (Kremer et al, 2015c). The mobilized volumes are in the same order of magnitude than similar events in the marine realm (Hampton et al, 1996;Talling, 2014).…”

“…As an example, the Nice airport scarp failure in 1979 evolved into a hybrid flow that mobilized 8 Â 10 6 m 3 -similar to the volume displaced by the 1998e2000 CE MTD event -and triggered a tsunami wave 2e3 m height (Mulder et al, 1997). A simplified tsunami wave numerical model of Lake Geneva (Kremer et al, 2015c) has recently shown that mass movements involving sediment volumes of 10 6 e10 7 m 3 could lead to 1e3 m high waves, reaching the adjacent lakeshore in only a few minutes. In the present case, no significant sudden lake level change was recorded in Lake Geneva limnological stations between 1998 CEe2000, a priori indicating that the 1998e2000 CE event did not trigger a tsunami wave.…”

Morphological signatures of mass wasting and delta processes in a fjord-lake system: insights from Lovatnet, western Norway

“…At Hellsete, onshore landslide debris confining the delta plain, major irregular debris at the delta toe, and a distinct debris lobe laterally to the delta slope, also indicate a significant influence of landslide and avalanche activity. Deltaic protuberances and other special features associated with delta collapse have been reported from other fjord-type lakes (e.g., Hilbe & Anselmetti, 2014;Kremer et al, 2015). These authors have assigned such features to seismic events or overloading due to rock falls, respectively.…”

“…This includes the information on depositional products as well as the behaviour and causal relationships between sedimentary processes. Such information is especially crucial for the understanding of hazardous events in the basins (e.g., Bøe et al, 2003;Longva et al, 2003;Blikra et al, 2006;L'Heureux et al, 2009L'Heureux et al, , 2012Ledoux et al, 2010;Hilbe et al, 2011Hilbe et al, , 2014Van Daele et al, 2013;Haeussler et al, 2014;Kremer et al, 2015;Wiemer et al, 2015). In Figure 1 this context, the linkage of offshore-onshore datasets is crucial as it provides clues to the many processes that occur in both environments (e.g., Bozzano et al, 2009;Couchon-Voyer et al, 2011).…”