Probability Maps of Landslide Reactivation Derived from Tree-Ring Records

Probability maps of landslide reactivation are presented for the Aiguettes landslide located in the southern French Alps based on results obtained with dendrogeomorphic analysis. Spatio-temporal activity was derived from tree-ring series of 223 disturbed trees. 355 growth disturbances were identified in the samples indicating 14 reactivation phases of the landslide body between 1898 and 2011. Probabilities of landslide reactivation were computed and illustrated using a Poisson distribution model. For example, in the toe, the probability increases from 0.28 for a 5-year period to 0.99 for a 100-year period. This method differs from conventional approaches, which have demonstrated to have limitations in the prediction of spatiotemporal reactivation of landslides. Based on extensive data and therefore allowing determination of quantitative probability maps of reactivation, this approach is considered a valuable tool for land managers in charge of protecting and forecasting people as well as for those responsible for land-use planning and management.