Snow avalanche synchronicity derived from a multi-path tree-ring reconstruction in the Fagaras Mountains (Southern Carpathians, Romania)

Snow avalanches pose a constant threat to human lives, property, and infrastructure in mountainous regions worldwide. To efficiently manage avalanche-related hazards and risks, knowledge of past occurrences is crucial. In many mountain regions, archival records on past events are scarce or even completely missing. Therefore, natural archives, such as tree-rings, are widely used as proxies to build century-long snow avalanche chronologies. However, most dendrogeomorphic studies focus on a small number of sites, providing only path-scale reconstructions with limited significance for a larger area. To overcome this problem, in the present study, we analyzed 17 avalanche paths in a small and relatively homogeneous region located in the Fagaras Mountains, Southern Carpathians, and documented past snow avalanche activity with dendrogeomorphic techniques. Increment cores extracted from 933 Picea abies trees allowed the reconstruction of a total of 174 snow avalanche years across all investigated paths. At the same time, widespread snow avalanche occurrence was identified in the study area. In years such as 1923, 1929, 1988, 1992, 1995, 1997, 2002, and 2005, more than half of the investigated paths experienced at least a major snow avalanche event. Regarding the frequency of event years, we conclude that the mean recurrence interval of widespread/extreme events is 4.1 years. Finally, this study highlights the importance of investigating multiple avalanche paths in a small, homogeneous area to create a better understanding of snow avalanche activity at path-and mountain range-scale.