Dendrogeomorphology and high-magnitude snow avalanches: a review and case study

Abstract

Abstract. The application of the principles of dendrogeomorphology for the dating of high-magnitude snow avalanches is well established in the natural hazards literature. A variety of methodologies are employed by different authors, however, and no standardization currently exists for appropriate sample sizes, the issue of "weighting" certain tree-ring responses as more important than others, or the minimum number of responding trees required in order to infer an avalanche event. We review the literature of dendrogeomorphology as it applies to snow avalanches, and examine the questions of sample size, type of ring reactions dated and weighted, and minimum responses. We present tree-ring data from two avalanche paths in the Rocky Mountains of Montana, USA, from trees uprooted by major snow avalanches in the winter of 2002. These data provide distinct chronologies of past avalanche events, and also illustrate how the critical choice of a minimum Index Number can affect the number of avalanche events in a final chronology based on tree-ring analysis.

Wind contribution to yearly silver fir (Abies alba Mill.) compression wood development in the Romanian Carpathians

“…Dendrochronological analyses have demonstrated the utility of compression wood in reconstructing the wind-load history of trees (Pillow 1931, Schweingruber 2007 and dating geomorphological events such as snow avalanches, landslides and earthquakes (Butler & Sawyer 2008, Stoffel & Bollschweiler 2008, as well as major windstorms and snowfall (Cherubini et al 1996). Previous studies (e.g., Panayotov & Yurukov 2005) analysed the incidence of compression wood as time series, but they did not detrend and did not calibrate them in relation to wind climate.…”

Implications of spatial distribution of rockfall reconstructed by dendrogeomorphological methods

“…This technique has successfully been applied to the spatio-temporal analysis of debris-flow activity (Bollschweiler et al, 2007;Pelfini and Santilli, 2008;Šilhán and Pánek, 2010;Stoffel, 2010), snow avalanches (Butler and Sawyer, 2008;Casteller et al, 2008), landslides (Fantucci and Sorriso-Valvo, 1999;Stefanini, 2004;Lopez-Saez et al, 2012a, b;Šilhán et al, 2013) and gully erosion (Corona et al, 2011;Stoffel et al, 2012). The great advantage of dendrogeomorphic methods is that they allow rapid acquisition of data, which is otherwise accessible only by means of long-term field monitoring.…”

Meta-analysis of dendrochronological dating of mass movements

“…Early studies regarding snow avalanches have been performed in the northern U.S., particularly in Wyoming, Colorado and especially Glacier National Park (Montana) (Butler and Malanson, 1985), which still attractive for researchers (Reardon et al, 2008;Butler and Sawyer, 2008). However, since the turn of the millennium, attention has also been aimed at other mountains, e.g., the Alps (Casteller et al, 2007;Corona et al, 2010), the Pyrenees (Muntán et al, 2009) and the Andes (Mundo et al, 2007;Casteller et al, 2011).…”

“…Shroder's (1978) procedure can also be used to study landslides (Stefanini, 2004) or debris floods (Mayer et al, 2010). The threshold value should usually be set, in the case of avalanches, between 10 and 40% (Butler and Sawyer, 2008); traditionally, it has been set at 10% (Reardon et al, 2008). Very detailed methodological research on the problem of setting the appropriate level of this index performed by Corona et al (2012) pointed to the need to increase the threshold with decreasing sample size; otherwise, many past avalanches can be omitted and potential noise (identification of "false" events) can occur.…”