Iceland Mag

13 Reykjavik

Iceland Mag

Geology

Massive rockslide in W. Iceland: Unusually heavy rain of recent weeks, months likely causes

By Staff

  • The forces of nature Relentless rains weakened the mountain. Photo/Sumarliði Ásgeirsson

  • Blocking the river The river Hítará formed a new lake before it found a new path around the rockfall. Photo/Sumarliði Ásgeirsson

  • The new lake The river is considered one of the best salmon fishing rivers in West Iceland. Photo/Jón G. Guðbrandsson

  • Finding a new route The river Hítará has found a new route around the rockslide. Photo/Sigtryggur Ari

A massive rockfall in West Iceland on Saturday morning is believed to be one of the largest rock slides since Iceland was settled in the 9th century. A large part of the south-east slope of Fagraskógarfjall mountain collapsed into Hítardalur valley where it blocked Hítará river, one of the best salmon fishing rivers in Iceland. Fortunately nobody was injured in the rockfall, but local farmers and fishermen fear that the rockfall has destroyed important spawning grounds for salmon, potentially threatening the future of salmon fishing in the river.

Geologists believe that the relentless rainfall in recent weeks and months created the conditions for the rockfall. The rain hammered water down into deep cracks and fractures in the mountain, creating outward pressure and reducing the integrity of the rock, allowing a large part of the mountain side slide off down into the valley below. Saturday's rock slide has been followed by numerous smaller mud- and rock slides in Fagraskógarfjall. According to experts at the Icelandic Meteorological Office the event in Hítardalur should not be interpreted as a sign other similar disasters will take place in coming days.

People are asked to stay away from the mountain side of Fagraskógarfjall in coming days. 

The size of the rockfall has not been determined, but a geologist who spoke to the National Broadcasting Service RÚV that it is most likely one of the largest, if not the single largest rockfall since the ninth century. The rock slide fell 1.5 km (0.9 mi) from the hillside, covering an area more than 1 km (0.6 mi) wide, completely blocking the riverbed of the river Hítará. RÚV reports that a 5 km (3.1 mi) long stretch of the river was left completely dry by the rockfall.

The IMO estimates that the rockfall delivered 10-20 million square meters of material into the valley. A second 20 million square meter rock fall took place by Öskjuvatn crater lake in the Central Highlands in 2014.

A large lagoon formed above the rock slide, but by Sunday the river had found a new route around the rockfall, raising hopes that the disaster will not have permanent affects on the wild salmon in the river.

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