Analyses of past and present rock slope instabilities in a fjord valley: Implications for hazard estimations

摘要

For quantitative hazard assessment it is necessary to define the magnitude-frequency distribution and a temporal model of the landslide frequency. This is often complicated for large rock slope failures due to the lack of significant numbers of large rock slope failures in inventories of a given homogeneous region or sparse information about the timing. An inventory of 108 rock slope failure deposits within the fjords of the Storfjord region including a relative rockslide chronostratigraphy was available for this study. The temporal distribution of rock slope failures is characterized by a rapid response with a high frequency of failures directly after deglaciation followed by a lower constant frequency since 9,000 years BP for the entire Storfjord region. The largest recorded volumes failed directly after deglaciation. Volumes larger than 5 x 10(6) m(3) have not been recorded within the last 9,000 years.