METEOROLOGICAL TRIGGERING FACTORS AND THRESHOLD CONDITIONS FOR SHALLOW LANDSLIDING AND DEBRIS-FLOW ACTIVITY IN ICELAND

• Main Authors: V. R. Schaefer, R. L. Schuster, A. K. Turner, Saemundsson Th, Decaulne A
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1475
• Subjects: Iceland
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.554.2493; http://geolab.univ-bpclermont.fr/armelle/publi/Colorado-meteo_1475-1485.pdf

Abstract: Shallow landslide and debris-flow activity in Iceland is frequent, often causing significant threats to many small towns and villages around the island. The main threatened areas are located in the eastern, central north and northwestern parts of Iceland. The landscape in these areas is characterized by narrow glacially eroded fjords and steep mountain slopes, often covered by debris talus. The triggering factors and threshold conditions for shallow landslides and debris flows vary in these three areas, mainly due to precipitation distribution. In eastern Iceland, shallow landslides and debris flows occur after long-lasting rainfall or intense rainfall. In central northern Iceland, snowmelt is the main triggering factor, then rain-on-snow, and long-lasting rainfall. In the northwestern part of the island long-lasting rainfall and rain-on-snow are the dominant triggering factors. Measurements of the amount of precipitation needed to trigger a shallow landslide or a debris flow has been documented in northwestern, northern and eastern Iceland to define the threshold conditions. These measurements show, for example, that in the eastern part of the island approximately 100 mm of rain falling over 24 hours is needed, while precipitation lower than 50 mm and/or rapid snowmelt are more suitable triggering factors in the northern and northwestern parts of the country.