“Late Quaternary lacustrine paleo-seismic archives in north-western Alps: Examples of earthquake-origin assessment of sedimentary disturbances”

The late Quaternary sedimentary fills of several lakes of the north-western Alps are revealed to be possible paleo-seismological “archives” in a moderately active seismo-tectonic region. The strongest historically reported events can be correlated with specific layers, whose textures result from different processes: i) mass failures of sub-aqueous slope deposits (especially delta foresets) evolving into hyperpycnal currents influenced by seiche effects and/or multiple reflections on lake basin slopes; ii) in situ liquefaction and flowage; and iii) micro-fracturing. Based on identification of the sedimentary signature of a well-documented historical earthquake, the paleoseismic interpretation can be extrapolated back to 16,000 yrs BP with a reconstruction of a time series and textural identification of slope failure-related turbidites (the most frequent earthquake signature). The obtained time series are compatible with historical seismicity in terms of recurrence interval.