The GeoExtreme project, Module A: Historical landslide and avalanche events

Category Environmetal Geology
Group GSI.IR
Location International Geological Congress,oslo 2008
Author Jaedicke, Christian۱; Kronholm, Kalle۱; Isaksen, Ketil۲; Vikhamar-Schuler, Dagrun۲
Holding Date 11 October 2008

The objective of Module A in the GeoExtreme project is the establishment of statistical relationships between landslide and avalanche events and distinct meteorological elements. Each slide event is preceded by a complex interaction of various processes acting at both short and long time scales. The complexity is enhanced by local variations in parent material and makes it difficult to predict deterministically the time and location of a new event. Short- and long-term meteorological variables such as precipitation and temperature exhibit a strong control on the timing of geohazard events in a given location and can be used to predict the probability of a geohazard event in a certain area. A database with more than 20.000 recorded geohazard events was coupled to a climate database to evaluate the predictability of event triggering from meteorological elements. Events from all parts of Norway and a time span from 1961 to 2005 are included. The database is divided into snow avalanches, clay-, debris-, and rock slides, and mainly includes events that have in some way interfered with humans or infrastructure such as roads, railway lines or houses. The climate database contains daily maps of a number of meteorological variables for Norway with 1 km resolution. For each landslide and avalanche event values of meteorological elements have been extracted based on its location and date. These values are used as independent variables to predict days with slide events on the local, regional and national scale using classification trees. The analysis shows a high degree of predictability of event days at the local scale, but a decrease in predictability with increasing scales. The most important meteorological triggering elements are generally related to precipitation but these show spatial variations, reflecting the varying climates in the country. A frequency analysis on the results shows that the number of days with meteorological conditions that can lead to landslides and avalanches is strongly dependent on seasons and climate zones in Norway. The results from this work build the basis for the analysis of future changes to event probabilities in a changing climate.