The Republic of North Ossetia, in the northern Caucasus, is home to the Kolka Glacier, famous for its surges. The glacier lies at the head of the Genaldon River basin, in close proximity to Maili, another, larger glacier. Kolka is a cirque glacier, formed in a basin on the side of the mountains. Fed throughout the year by avalanches from above, it accumulates both ice and sub-glacial meltwater. These characteristics have, historically, led to instability and sudden surges. In the past villages were built only on the slopes but, more recently, settlements have unwisely been built on the valley floor.
During the evening of September 20 2002, a terrible disaster occurred when vast amounts of ice, water and rock broke free and plunged down into the Genaldon river valley. The avalanche devastated everything in its path, finally bursting into the Karmadon Depression – at the northern end of which a narrow entry way leads into a gorge. Here the avalanche should have been halted. Instead, the gap was blocked by huge chunks of rock and ice that still allowed mud and icy water to surge through and destroy everything for the next 17 km (11 mi). The ice within the debris quickly melted, flooding settlements and forming new lakes. Some 125 people were killed and the village of Nizhnii Karmadon, along with several rest houses beside the river below (the area was popular with trekkers), were totally obliterated.
This was the most powerful surge ever recorded here. The tongue of the glacier, which lies at about 3,000 m (9,842 ft), was ripped away, leaving the cirque completely empty. The vast amount of sub-glacial water that had accumulated produced so powerful a surge that the glacier was virtually thrown from its basin – the first time such a phenomenon has been observed.
When: September 20 2002
Where: North Ossetia
Death toll: 125 people were killed and many others injured.
You should know: Among those who lost their lives in the Kolka Glacier surge were Russian actor and director Sergei Bodrov and a film crew of 27. The glacier itself was visible again a mere two years later and currently continues to grow.