Journal cover Journal topic
Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Nat. Hazards Earth Syst. Sci., 17, 613-625, 2017
http://www.nat-hazards-earth-syst-sci.net/17/613/2017/
doi:10.5194/nhess-17-613-2017
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
08 May 2017
A multi-centennial record of past floods and earthquakes in Valle d'Aosta, Mediterranean Italian Alps
Bruno Wilhelm1, Hendrik Vogel2, and Flavio S. Anselmetti2 1University Grenoble Alpes, CNRS, IRD, INP-G, Institut des Géosciences de l'Environnement, 38000 Grenoble, France
2Institute of Geological Sciences and Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
Abstract. Mediterranean Alpine populations are particularly exposed to natural hazards like floods and earthquakes because of both the close Mediterranean humidity source and the seismically active Alpine region. Knowledge of long-term variability in flood and earthquake occurrences is of high value since it can be useful to improve risk assessment and mitigation. In this context, we explore the potential of a lake-sediment sequence from Lago Inferiore de Laures in Valle d'Aosta (Northern Italy) as a long-term record of past floods and earthquakes. The high-resolution sedimentological study revealed 76 event layers over the last ca. 270 years; 8 are interpreted as most probably induced by earthquakes and 68 by flood events. Comparison to historical seismic data suggests that the recorded earthquakes are strong (epicentral Medvedev–Sponheuer–Kárník (MSK) intensity of VI–IX) and/or close to the lake (distance of 25–120 km). Compared to other lake-sediment sequences, Lago Inferiore de Laures sediments appear to be regionally the most sensitive to earthquake shaking, offering a great potential to reconstruct the past regional seismicity further back in time. Comparison to historical and palaeoflood records suggests that the flood signal reconstructed from Lago Inferiore de Laures sediments represents the regional and (multi-)decadal variability of summer–autumn floods well, in connection to Mediterranean mesoscale precipitation events. Overall, our results reveal the high potential of Lago Inferiore de Laures sediments to extend the regional earthquake and flood catalogues far back in time.

Citation: Wilhelm, B., Vogel, H., and Anselmetti, F. S.: A multi-centennial record of past floods and earthquakes in Valle d'Aosta, Mediterranean Italian Alps, Nat. Hazards Earth Syst. Sci., 17, 613-625, doi:10.5194/nhess-17-613-2017, 2017.
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Short summary
We explored the potential of a sedimentary sequence in Valle d'Aosta (Northern Italy) as a natural archive of hazards. Our results suggest that this sequence is regionally the most sensitive to earthquake shaking with the record of 8 earthquakes over the last ~270 years and that it well represents the regional and (multi-)decennial variability of Mediterranean summer–autumn floods. Hence, this sequence offers a great potential to extend chronicles of regional floods and earthquakes back in time.
We explored the potential of a sedimentary sequence in Valle d'Aosta (Northern Italy) as a...
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