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Titre du document / Document title

Late Pleistocene earthquake-triggered moraine dam failure and outburst of Lake Zurich, Switzerland

Auteur(s) / Author(s)

STRASSER M. (1) ; SCHINDLER C. ; ANSELMETTI F. S. (2) ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

(1) Geological Institute, Swiss Federal Institute of Technology Zurich, Zurich, SUISSE
(2) Sedirnentology Group, Department of Surface Waters, Swiss Federal Instiute of Aquatic Science and Technology, Dubendorf, SUISSE

Résumé / Abstract

[1] Lakes impounded by moraines may be considered hazardous in glaciated areas throughout the world because dams can fail suddenly producing destructive floods with peak discharges far in excess of normal flows. Here we present a comprehensive case study in the Zurich, Switzerland, area that reveals several independent lines of evidences for the occurrence of a Late Pleistocene (∼13,760 calibrated years B.P.) moraine breach and subsequent Lake Zurich outburst (discharge volume ∼2.5 km3). We use seismic and core data in order to track and date the geological fingerprint of this event. Data from areas downstream of the lake show coarse-grained massive (>25 m thick) reworked morainic deposits behind four breached zones. In Lake Zurich, sedimentary structures recorded in a paleowater depth of ∼36 m indicate strong outburst-induced currents. Hydrodynamic calculations reconstructing the sediment transport capacity explaining the observed bed forms allow estimating averaged outburst discharge to exceed minimum values of ∼2400 m3s-1. The potential maximal magnitude of the outburst is inferred from calculations considering critical flow conditions through the breaches revealing estimated peak discharge of ∼20,600 m3s-1. We also discuss long-term causes and short-term trigger mechanisms of the dam failure that occurred several thousand years after moraine formation and show that it coincides with a reconstructed strong northern alpine earthquake (magnitude >6.5). Our data thus suggest that catastrophic drainage of Lake Zurich was initiated as a consequence of the moraine dam failure that either was triggered by primary earthquake shaking or by secondary effects, such as overtopping by landslide-generated waves.

Revue / Journal Title

Journal of geophysical research    ISSN  0148-0227 

Source / Source

2008, vol. 113, noF2, [Note(s): F02003.1-F02003.16] (1 p.1/4)

Langue / Language

Anglais

Editeur / Publisher

American Geophysical Union, Washington, DC, ETATS-UNIS  (1949-2012) (Revue)

Mots-clés anglais / English Keywords

Europe

;

Central Europe

;

Switzerland

;

Phanerozoic

;

Cenozoic

;

Quaternary

;

Zurich Switzerland

;

Lake of Zurich

;

waves

;

landslides

;

drainage

;

Short term

;

Long term

;

bedforms

;

sediment transport

;

hydrodynamics

;

currents

;

depth

;

sedimentary structures

;

grains

;

trajectory

;

drill cores

;

case studies

;

critical flow

;

discharge

;

inundations

;

floods

;

rupture

;

dams

;

moraines

;

earthquakes

;

Pleistocene

;

Mots-clés français / French Keywords

Europe

;

Europe Centrale

;

Suisse

;

Phanérozoïque

;

Cénozoïque

;

Quaternaire

;

Zurich

;

Lac Zurich

;

Onde

;

Glissement terrain

;

Drainage

;

Court terme

;

Long terme

;

Configuration lit

;

Transport sédiment

;

Hydrodynamique

;

Courant

;

Profondeur

;

Structure sédimentaire

;

Grain

;

Trajectoire

;

Carotte

;

Etude cas

;

Ecoulement critique

;

Débit

;

Inondation

;

Crue

;

Rupture

;

Barrage

;

Moraine

;

Séisme

;

Pléistocène

;

Mots-clés espagnols / Spanish Keywords

Europa

;

Europa central

;

Suiza

;

Fanerozoico

;

Cenozoico

;

Cuaternario

;

Lago Zurich

;

Desmoronamiento tierra

;

Corto plazo

;

Largo plazo

;

Configuración lecho (río)

;

Hidrodinámica

;

Profundidad

;

Estructura sedimentaria

;

Grano

;

Testigo

;

Estudio caso

;

Gasto

;

Crecida

;

Ruptura

;

Presa

;

Morrena

;

Sismo

;

Localisation / Location

INIST-CNRS, Cote INIST : 3144, 35400019738427.0030

Nº notice refdoc (ud4) : 20566697



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