Landslide: Extent and economic significance in Norway

The landslide problem in Norway is dominated by quick-clay slides. The largest of these occurred in Gauldalen in 1345 and killed 500 people. In 1983, a quick-clay landslide killed 112 people at Verdalen, and another at Rissa in 1978 destroyed 7 farms and 5 houses. On average, 15 people are killed by landslides each year, but a few catastrophes account for most fatalities. Rockfalls and rock slides are common in western Norway where ice-eroded valleys and fjords expose bedrock on very steep slopes. Waves generated by some of these rockfalls and slides have killed as many as 73 people in a single event. Debris slides and debris flow are most common in the western coastal region. Measures for mitigating landslides disasters in Norway including building structures to protect existing buildings, evacuating structures at risk, and preparing maps showing “safe” areas and areas at risk. The mapping program will cost 6 to 7 million US$ over a 12 year period. The annual cost of landsliding in Norway is estimated to be about 6 million US$ in average.