Distribution and spatial analysis of rockslides failures in the Icelandic Westfjords: first results
Résumé
Rockslides are numerous in the Icelandic Westfjords. In this study, the large visible rockslides have been inventoried
in a first stage, by observation of aerial images and subsequent photo-interpretation. A total of 186 rockslides has
been recorded and in a second stage, their distribution has been studied, using Geographic Information Systems
and statistical methods like Kernel Density Estimator (KDE). The relief of the studied area is closely related with the
glacial and interglacial periods. Rockslides are mostly concentrated close to the coast, where the relief is dominantly
shaped by glaciers exposing high slopes, while the inner part mainly constituted of plateaux is not prone to mass
movements. Nevertheless, the statistical analysis does not show a strong correlation between slope gradient and
rockslides concentration, as the null hypothesis is not rejected. Other causes already mentioned by several authors
are consistent with the location of rockslides, such as favourable dip or mass movement occurrence in the Tertiary
basalts. These elements cannot explain the spatial distribution of rockslides in the West! ords by themselves, at a
regional scale. The deglaciation pattern might provide an explanation for this spatial distribution, even without
precise dating. This work provides a new database where commonly claimed triggers do not provide a satisfactory
explanation to the spatial distribution of rockslides in the Icelandic Westfjords.