Landslide disaster

Terrible devastation was caused by a landslide in the Schwyz district on 2 September. Late in the afternoon, after heavy rainfall, a rocky peak of the Rossberg broke off. The earth masses underneath started to slide and buried the villages of Goldau and Röthen as well as parts of Lauerz and Buosingen within a few minutes. 457 people died in the natural disaster.

In the weeks before, it had rained almost continuously, softening the layers of earth. Around 5 p.m., the rock masses broke loose and thundered violently down into the valley. Blocks of rock weighing several centimetres were hurled through the air, taking houses, people and livestock with them. The destructive earth masses buried the neighbouring villages under a ten to fifty metre high layer of rubble and even rolled up the Rigiberg opposite. Some of the rock masses thundered into Lake Lauerz. This triggered a tidal wave that also claimed several lives.

A total of 457 people were killed in the Goldau landslide. Among them were seven people from a group of travellers from Bern, who were arriving in Goldau at the time of the landslide. 111 dwellings, 2 churches and 2 chapels were buried, 220 barns and stables destroyed and 323 head of cattle killed. Next to the Basel earthquake of 1356, the Goldau landslide is the largest natural disaster in Switzerland to date.

Appeal for donations

The Swiss Confederation has already reacted to the Goldau disaster: the neighbouring cantons of Zug and Lucerne sent relief workers to the affected region as early as yesterday. Delegates from Zurich and Bern are also expected to arrive soon to support the recovery work and the reconstruction of the villages. Rapid help is now needed for the survivors. Switzerland is therefore appealing for donations throughout the country. You too can help the victims of the Goldau landslide! Addresses and information can be obtained directly from the editorial office.

Earth on the move – landslides, mudflows and landslides

Suddenly the earth starts to move: tons of rock, mud and debris slide or tumble down the mountain into the valley. Destructive and unstoppable, the earth’s masses sweep away everything in their path.

Erosion can proceed very slowly, but sometimes it happens suddenly. If, after a heavy downpour, the soil softens considerably and is heavy enough, an entire slope can start to slide. Such a landslide transports large amounts of earth and debris down into the valley. At the foot of the slope, the loosened rock collects in debris cones and heaps.

Whether a landslide occurs depends on the slope: The steeper the slope, the more likely the earth is to slide. How firmly the layers of earth hold together also plays a role. If the slope is overgrown with plants, the roots provide more grip. If nothing grows on the slope or trees have been cleared, the roots that hold the soil in place are missing. Then it is easier for a landslide to occur.

A landslide can look different: The whole slope can slide downwards over a large area. Or earth and mud flow like a river through a valley or carve one out, then it is called a mudflow.

In the shortest possible time, huge masses of rock go down in a landslide. Debris and rocks tumble down within a few seconds. Mostly, landslides happen at places where different rock layers meet. Heavy precipitation, the alternation of heat and cold or earthquakes can cause these layers to separate. In a landslide, large blocks of rock break off. Due to global warming, layers of rock that used to be held together by ice are thawing today. As a result, such landslides are occurring more and more frequently.

Landslides and rockslides are very dangerous. They have already cost many lives and destroyed entire villages. In the Goldau landslide in Switzerland, for example, forty million cubic metres of rock fell, burying several villages and hundreds of people underneath.

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What causes erosion?

When rock weathers, it rarely stays in its original place. Often, rock debris rolls down the slope, is washed away by water or pushed away by ice masses. Fine rock dust or sand can also be carried by the wind. Whether the rock is carried away by water, ice, wind or gravity, all these processes are called erosion.

The erosion caused by flowing water is particularly drastic. Streams and rivers dig a bed in the ground, rock slides down and a valley forms. When a glacier rolls down the valley, it planes the valley wider by dragging debris with it. Such trough valleys show that there was a glacier here long after the ice has melted. The surf of the sea, on the other hand, attacks the coast. Steep cliffs are eroded and collapse, sandy beaches are washed away by the waves. In deserts, the wind sweeps away large areas of sand. The harder it blows, the more sand it can carry away. A sandstorm gradually grinds away obstacles made of solid rock like a sandblaster.

When rain and wind wash or blow away the soil cover on large areas, this is called soil erosion. Landslides on slopes are also referred to as soil erosion. The problem is that the fertile upper layer of the soil disappears. In the worst case, it can no longer be used for agriculture.

If the soil is overgrown with plants, this slows down erosion. The roots of the plants hold the soil in place and prevent wind and water from carrying it away. However, if the plant cover is destroyed, for example by deforestation, the soil lacks this hold and is eroded away.

From rock to grain of sand – Weathering

Today, northern Canada is a gently undulating landscape. Many millions of years ago, however, a mountain range stood here. In fact, over a very long time, even high mountains can turn into small hills.

The reason for this transformation: the rock on the earth’s surface is constantly exposed to wind and weather. If, for example, water penetrates into cracks in the rock and freezes, it blasts the stone apart. This process is called frost blasting. Changes in temperature between day and night and the force of water and wind also cause the rock to become friable. In other words, it weathers. This process can also be observed on buildings or stone figures. During weathering, the rock breaks down into smaller and smaller components down to fine grains of sand and dust. Different rocks weather at different rates: granite, for example, is much more resistant than the comparatively loose sandstone.

Some types of rock even dissolve completely when they come into contact with water, for example rock salt and lime. Rock salt is chemically the same as table salt – and that already dissolves in ordinary water. Lime is somewhat more resistant, but limestone also dissolves in acidic water. Acid is formed, for example, when rainwater in the air reacts with the gas carbon dioxide. This “acid rain” attacks the limestone and dissolves it over time. On the earth’s surface, weathering leaves behind fissured limestone landscapes, while caves form underground.

Cut off from the mainland

For hours yesterday, two tourists were trapped on a rock in the roaring sea. One of the two arches of the rock sculpture “London Bridge” on Australia’s famous “Great Ocean Road” suddenly collapsed. This cut off the visitors’ way back. They had to be rescued by a helicopter.

The young couple had walked to the end of the second arch to enjoy the fantastic view of the sea and coast. Once there, they heard an ominous crunching sound. When they looked around, the arch had already collapsed, cutting the connection to the shore. Fortunately, no one had just stayed on the first arch, there were no other victims. After five hours of waiting, the couple was happily brought back to shore by a helicopter.

The double arch of “London Bridge” was one of the most famous rock formations on Australia’s south coast. Wind and waves are increasingly eroding this coastline, causing part of the tourist attraction to now collapse. After the collapse, the “London Bridge” was renamed without further ado: It is now called “London Arch”.

On the Great Ocean Road

The surf is wild on Australia’s south coast, along which the famous Great Ocean Road runs. The stormy sea has already claimed many victims here: Over a hundred ships have already been wrecked on the rocky coast. Wind and waves grind up everything in their path here. And that is above all the relatively soft limestone with its bizarre rock colossi: London Bridge was only one of them, the “Twelve Apostles” or the “Island Archway” are also world-famous. The collapse of “London Bridge” shows how fragile the coast is: the rock disintegrates in the raging sea almost like sugar in hot tea. Without pause, the forces of nature gnaw at the coast and reshape it. So if you still want to see the twelve apostles in all their glory, you should hurry.

Alarm in the Alps

It is the mightiest of all Alpine glaciers: the Aletsch Glacier in the Bernese Alps is over 23 kilometres long. Its ice cover is up to 900 metres thick. For now! Because the white splendour of the glaciers could soon be history.

For decades, researchers have been observing that the ice masses are shrinking. On average, they are losing half a metre of thickness per year. Climate change, which is causing the earth’s temperatures to rise, is to blame: In the increasingly warmer summers, more ice melts than is added in the cold season. The hot summer of 2003 was particularly hard on the ice giants: At that time, large parts of the glaciers melted away. In the meantime, it is even feared that the Alpine glaciers could disappear in as little as 30 years.

This would be a great loss for the landscape of the Alps – and a disaster for tourism: many winter sports resorts live from skiing on glaciers. If ice and snow melt, tourists will also stay away. In addition, there will be problems with the water supply if the glaciers die. Their ice masses store enormous amounts of fresh water. Many places would then have to transport their drinking water expensively and from far away.

Cling film for glaciers

To protect their glaciers from rising temperatures, the Austrians have come up with something: they cover their glaciers in summer with plastic cling film. The white film, just under four millimetres thick, is supposed to reflect the sun’s rays and thus prevent the ice and snow from melting. And indeed: Glacier researchers confirm that the film greatly reduces melting.

Glacier foils are now also being used in Switzerland and Germany. The Zugspitze, too, now regularly gets a “sun hat”. Climate protectionists criticise that this may slow down the melting of the ice for a while, but it will not stop global warming.