Interaction between weather variations and large scale displacements along the Siglufjarðarvegur road in the Almenningar area, in central North Iceland

In 1968 a road was constructed along the coast on the western side of the Tröllaskagi peninsula in central north Iceland. The road, which until 2010 was the only whole year road to the town of Siglufjörður, crosses three large landslides, the Hraun landslide in the south, the Þúfnavellir landslide and the Tjarnardalir landslide in the north, in an area named Almenningar. Since its construction extensive damages have occurred on the road often causing hazardous conditions.

In 1977 the Icelandic Road and Coastal Administration began to monitor the deformation. In the beginning the measurements were achieved with several years intervals, but over the last decades yearly measurements have been carried out. In the year 2022, nine GNSS stations were installed along the road and a rain gauge, giving us for the first time the possibility of 24/7 monitoring on the displacements and connect the movement to weather variations, such as temperature variation and precipitation.

The dataset, which spans now over 47 years, gives us a unique opportunity to correlate the displacements on the road to external factors. Written source of deformation in the Almenningar area dates back to 1916 and since then more than 50 movement events have been listed affecting the road.

These measurements show the deformation along the road, but recent studies using “feature tracking” and InSAR show us that the whole landslide masses show signs of movement.

Our studies show that the highest movement rate takes place along the frontal parts of the landslide masses and that the movement is strongly related to both weather variations, e.g. precipitation, snowmelt and coastal erosion.