Natural Hazards and Earth System Science www.nat-hazards-earth-syst-sci.net 1561-8633 1684-9981 9 5 2009 10.5194/nhess-9-1599-2009 http://www.nat-hazards-earth-syst-sci.net/9/1599/2009/ http://www.nat-hazards-earth-syst-sci.net/9/1599/2009/nhess-9-1599-2009.html http://www.nat-hazards-earth-syst-sci.net/9/1599/2009/nhess-9-1599-2009.pdf 1599 1612 2009-09-28 Reconstructing snow avalanches in the Southeastern Pyrenees E. Muntán emuntan@ub.edu C. García P. Oller G. Martí A. García E. Gutiérrez Dendroecology, Department of Ecology, University of Barcelona, Diagonal 645, 08028 Barcelona, Spain Geological Hazards Unit, Geological Institute of Catalonia, Balmes 209–211, 08006 Barcelona, Spain Group of Climatology, Department of Physical Geography and Regional Geographical Analysis, University of Barcelona, Montalegre 6, 08001 Barcelona, Spain A regional study of snow avalanche processes was undertaken in the SE Pyrenees. Dendrogeomorphology was used to date and reconstruct large-scale snow avalanche events that occurred in the last four decades. Dendrochronological analyses yielded the dates of nine winters when avalanches occurred in the recent past in six studied avalanche paths. Some of these avalanches were already known, but others had not been documented. In one case, the existing avalanche path map was improved with the dendrogeomorphological information of a larger past event. As a result of the dendrogeomorphological analyses, evidence for three regional-scale major avalanche years was identified in the SE Pyrenees from 1971 to 2004: 1971–1972, 1995–1996 and 2002–2003. The specific synoptic atmospheric situations and the most likely nivometeorological and snowpack conditions that released these major avalanches were determined using weather data for the seasons of major avalanche releases. In 1971–1972 the snow avalanche episode was characterized by a deep trough crossing the Pyrenees. 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