Tree rings as an early warning against catastrophic landslides: Assessing the potential of dendrochronology for determining slope stability

• Published in: Dendrochronologia (Verona) Vol. 53; pp. 82 - 94
• Main Authors: Wistuba, Małgorzata, Malik, Ireneusz, Badura, Janusz
• Format: Journal Article
• Language: English
• Published: Elsevier GmbH 01.02.2019
• Subjects: Catastrophic landslides; dendrochronology; Early warning; engineering; growth rings; landslides; Landsliding; Picea abies; Poland; risk; Slope stability; stems; temporal variation; Tree-ring eccentricity; trees; Poland; Catastrophic landslides; Early warning; Slope stability; Tree-ring eccentricity; Landsliding
• ISSN: 1125-7865; 1612-0051
• DOI: 10.1016/j.dendro.2018.12.002

•activity of landslides is precisely recorded in seasonal rings of trees.•dendrochronology allows detecting slopes with high level of landslide hazard.•increasing slope instability is recorded as increasing level of tree-ring eccentricity.•analysis of eccentricity allows early warning against catastrophic landslides.•dendrochronology can be a useful tool for spatial management in landslide areas. We investigated three slopes (in southern Poland, the Carpathian Mts, and the Sudeten Mts) subject to catastrophic, sudden landslides. To reconstruct past landslide activity, we analysed the eccentricity of tree rings in the stems of Norway spruce (Picea abies) using a per cent eccentricity index method. We obtained data on year-by-year changes in eccentricity patterns of single specimens, as well as data on landslide events dated from the whole population of trees sampled on each slope (13–30 spruce trees). These data supplied indirect information on the temporal variability of landslide activity on the three slopes revealing that all three slopes were subject to frequent landslide activity (recurrence intervals 2.0–2.7 years) well before catastrophic events that occurred in 1997 and 2010. The study also showed that 3–5 years before a catastrophic event the sample trees started to record increasing ground instability demonstrated as an uninterrupted, sudden increase in the eccentricity of single trees. Our results suggest that the application of dendrochronological methods can reveal slopes at an increased risk of catastrophic landsliding well in advance. The methods we applied show great promise for forecasting catastrophic landslides and assessing landslide hazard, slope stability and the effectiveness of engineering works undertaken to stabilise landslides.