Graziella Devoli

Large-Scale Synoptic Weather Types and Precipitation Responsible for Landslides in Southern Norway

Open image in new window The contribution of large-scale synoptic weather types to the occurrence of weather-induced landslides was investigated for southern Norway. Landslides from the period 2000–2014 were analyzed on a regional scale, using existing climatic and landslide regionalizations. The classification provides a time series of landslide classes and Kruskal-Wallis tests and chi-tests were conducted to analyze how well the classification performs for each landslide region. The synoptic classification (SynopVis Grosswetterlagen, SVG) of daily weather types was later compared with the precipitation classification. In order to predict the occurrence of landslides within a region, a logistic regression analysis was used where the independent variables were the SVG classes, mean daily rainfall and snowmelt. The results showed that in seven of the twelve landslide regions in southern Norway the SVGs have the highest predictive power in terms of landslide occurrence. In these regions, with the exception of one, the models are significantly better than a null model, and the models are good in predicting weather-induced landslide occurrence. The highest predictive probability of weather-induced landslide occurrence is given by the weather type Zonal Ridge across Central Europe (BM), which yields a 90% probability of weather-induced landslides on the west coast.

The Norwegian forecasting and warning service for rainfall- and snowmelt-induced landslides

The Norwegian Water Resources and Energy Directorate (NVE) has run a national flood forecasting and warning service since 1

Collection of Data on Historical Landslides in Nicaragua

Systematic studies of landslides in Nicaragua started only after the disastrous impact of Hurricane Mitch at the end of October 1998, which caused widespread and devastating slope failures. An attempt to collect, integrate and analyze historical data is made in order to improve the current information on landslides. In the period between 1570 and 1988, 135 historical landslides were found through the review of catalogues, newspapers, monographs, technical reports, bulletins and scientific papers. The type and quality of information collected, and the methodologies and techniques used to analyze the data are described. The analysis has allowed verifying that debris flows and rock falls have been the most common types of movement. Historical landslides have been triggered by high-intensity or long-duration rainfalls, earthquakes, hurricanes and volcanic eruptions confirming that landslides are not isolated phenomena but usually a consequence of other events. Besides hurricane Mitch, also other hurricanes have triggered landslides in the past. Data on damage and casualties are collected and integrated in a database. The spatial distribution of historical landslides shows that they have occurred mainly along the Pacific Volcanic Chain and few events were found within the Interior Highlands, the hilly relief of the Pacific Coastal Plain and the Atlantic Coastal Plain. The historical data help in improved understanding of landslide processes, their spatial and temporal distribution, as well as the economical and human losses caused by them, all of which are necessary for future landslide hazard and risk assessment in Nicaragua.