Glaciers as Natural Hazards

You may be surprised to discover that glaciers represent a very serious hazard to people...but only in certain places. Unlike hurricanes, earthquakes or tsunami waves that can strike highly populated areas, glaciers are usually found in remote and mountainous areas with very small human populations.

However, some are located near cities or towns and sometimes they do present a hazard for people living close by. It's not just glacial ice that can be hazardous. In fact, while the ice remains as a glacier it is probably very little threat to anyone at all. Even the fastest surging glacier can easily be avoided by just walking away from it. However, once a glacier starts to break up or melt, it can become a significant natural hazard.

Walkers and climbers may be hit by small chunks of ice and moraine as they move below a glacier snout, or huge sections of a glacier can avalanche for hundreds of meters with the power to obliterate people, roads, cars and buildings.

Lakes formed either below the snout, or on top of a glacier during the summer melt season may overflow and cause floods. In some cases the lake is held back by ice that suddenly gives way, resulting in an unexpected flood of water .

When glacial ice breaks off into the sea, icebergs are formed. These are a hazard for shipping. The waves created as the bergs break off the glacier can be several meters high and totally swamp small boats that venture too close to them.

The rest of this page details just a few of the occasions on which glaciers have demonstrated their potential as natural hazards.


Flooding Caused by a Glacier

In Peru in 1941, 6,000 people perished when a glacial lake suddenly burst open, flooding the town of Huaraz below it. Since then, another lake has formed at the base of the glacier, but engineers have created artificial channels to prevent future flooding.


Glacial flood prevented

In Svartissen, Norway, the Svartissen glacier drained into a lake at its snout. The lake was high up the side of a mountain and if the barrier of ice holding the water back had ever broken, the flood could have rushed down the valley towardsFebruary 23, 2006enty of free electricity, two underground tunnels were cut through the mountain and into the lake. Water flowing down the tunnels turned turbines to produce electricity - an economical way to reduce the risks and power the local town at the same time.

View across the drained lake at Svartissen

Swiss hydro-electric dam hit by avalanche

Ice avalanches from glacier snouts have been recorded in the Swiss Alps for centuries, and they still happen despite attempts to prevent them. In 1965, Switzerland was constructing a dam for a hydro-electric plant above the town of Mattmark. Without warning, an enormous mass of ice from the tongue of the nearby Allalingletscher broke off. In mere seconds, the avalanche had rushed down the slopes and buried much of the construction camp, killing 88 workers.


Huge avalanche near Chamonix, France

On 9th February 1999 a huge avalanche engulfed 17 chalets in France's Mont Blanc region near Chamonix. A dozen people were killed by the avalanche, two villages were cut off for days and hundreds of thousands of pounds of damage was done to building and roads. Temperatures dropped well below freezing overnight, making it almost impossible for rescue workers to find anyone under the snow and rubble even three days after the worst avalanche in the Chamonix valley in 91 years. Although avalanches are common in this are, 1999 saw more snow than had fallen for over 10 years and, although some special avalanche barriers worked, other unprotected areas were devastated.


Chamonix Avalanche Claims Climbers

On 23rd February 2005, two climbers, a high mountain guide aged 37 and his 48 year old client from the Vosges, were killed by an avalanche started by a massive sérac fall on the Argentière glacier close to Chamonix. The accident happened at 2,300 meters. Sérac falls are very difficult to predict, but if you want to climb on ice or cross a glacier, you will probably have to pass close to them, if not climb up through them!.


Vatnajökull Glacier Eruption: Iceland 1996

In October 1996 a volcano under the Vantajökull icecap began to erupt violently .A reservoir for the water melted by the volcano soon contained more water than it have ever contained, and officials anticipated a flood. They could not, however, say when it will hit, or how bad it would be. It actually took days before the water level had risen enough to overflow and sweep towards local settlements, but when it happened, it caused an estimated 15 million US dollars of damage. Almost a quarter of the bridges were destroyed, power and telephone lines came down, 6miles (10km) of roads were washed away and another similar length of road was badly damaged.



The Threat of Icebergs: The Titanic

Painting of the Titanic sinking after striking a bergIcebergs can be a significant threat in shipping lanes worldwide. Almost everyone has heard of the Titanic, which in April 1912 hit an iceberg that ripped a 90 meter hole in the ship. As it sank, 1,503 passengers died. The shipping lanes along the coasts of Greenland and Newfoundland were well known as danger areas, but in 1912 there was no RADAR, no satellite images and no coordinated reporting of where all the larger icebergs were drifting. Ships had to keep a very good look out, and go carefully.

Today, icebergs are still a major threat to shipping, but they are carefully monitored when they drift close to shipping lanes. Ships can have 'real time' images from satellites that track threatening bergs 24 hours a day and, unlike the Titanic, passenger ships carry enough lifeboats for all the passengers!




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