Flateyri – Avalanche defenses

In October 1995, a large avalanche from Skollahvilft struck on part of the settlement, killing 20 people. Previously, avalanches from Inner-Bæjargil had struck houses in the village without causing any casualties.

The avalanche defenses consist of two levees, 15 to 20 metres high and 600 metres long, as well as a catching dam, which is 10 metres high and 350 metres long. The dams are built from soil fill, which is taken from the landslide on both sides of the dams. They have great external steepness in order to increase their effectiveness against avalanches and at the same time significantly reduce the amount of material. The total volume of fills is 650,000 square meters.

The dams proved their worth immediately in the first years after their construction. In February 1999, a considerable flood from Skollahvilft fell on the inner dam and flowed with it all the way to the sea. In March 2000, a flood from Inner-Bæjargil fell on the outer dam and likewise flowed with it all the way to the sea. It is believed that without the defenses, both of these avalanches would have reached the settlement as it was before 1995.

Two large avalanches fell on Flateyri by Önundarfjörður in the evening of January 14, 2020. One of them fell from Skollahvilft and the other from Inner-Bæjargil. The avalanche defenses on the hillside above Flateyri diverted both avalanches into the sea, but part of the avalanches were thrown over the dams. Subsequently, the Avalanche Committee asked Verkís to make an audit of possible improvements to the avalanche defenses at Flateyri, and that during that audit, potential defense options for the harbour will also be examined.

The aim is to start construction on the improved avalanche defenses in Flateyri in the summer of 2023.

Verkís’ proposals for improved avalanche defenses are as follows:

Three rows of cones will be built above the existing levees in order to reduce the flood speed in both the stauchwall and the dense core before the avalanche reaches the levee and to separate the stauchwall and dense core during an avalanche.

The catching dam between the levees will be raised and rebuilt steeply with a slightly changed position, in order to reduce the risk of overflow.

Designing flood channels at both levees, in order to increase the effective height of the levees and ensure the unhindered flow of avalanches along the dams and into the sea.

Build a low but steep levee above the harbour in order to direct avalanches away from the harbour.

Install about 2 km of snow collection grids on Eyrarfjall, in order to reduce the frequency of avalanches at the beginning of winter from the catchment areas and thus further reduce the risk to settlements due to stauchwalls.

Reinforce window and door openings that face uphill, in all houses in risk area B, focusing on houses at the top of the risk area.