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

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Publication date 2015
Author Kremer Katrina, Hilbe Michael, Simpson Guy, Decrouy Laurent, Wildi Walter, Girardclos Stéphanie,
Project Quantifying human impact and recent climate change using clastic sediments from lacustrine records in Western Switzerland (Phase 2)
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Original article (peer-reviewed)

Journal Sedimentology
Volume (Issue) 62(5)
Page(s) 1305 - 1327
Title of proceedings Sedimentology
DOI doi: 10.1111/sed.12190

Open Access

URL https://archive-ouverte.unige.ch/unige:55598
Type of Open Access Repository (Green Open Access)

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.
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