What is a landslide, what causes them and which countries are prone to rockfalls and landslips?

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A LANDSLIDE sent sent rocks crashing to earth and caused terrified tourists to flee on the island of Zante.

As tourists on the island’s Navagio beach are injured following the landslide, we take a look at what causes them and which areas are most affected.

A huge wall of rock peels off the cliff at Navagio beach

What is a landslide?

A landslide is defined as the movement of a mass of rock, debris, or earth down a slope.

Geologists sometimes describe landslides as one type of mass wasting – any downward movement in which the Earth’s surface is worn away and also include rockfalls.

The term landslide encompasses five modes of slope movement – falls, topples, slides, spreads, and flows.

These are further subdivided by the type of material – bedrock, debris, or earth.

Debris flows, also commonly referred to as mudflows or mudslides, and rock falls are examples of common landslide types.

The powerful earthquake triggered deadly landslides that destroyed dozens of homes

The powerful Japan earthquake triggered deadly landslides that destroyed dozens of homes[/caption]

What causes them?

Landslides can be triggered by a number of factors including earthquakes, volcanic activity, changes in groundwater, a disturbance or change of slope.

Intense rainfall in a short period of time tends to produce, more shallow fast-moving mud and debris flows.

Steady rainfall over a long period of time may trigger deeper, slow-moving landslides.

The earth or rock might be weak or fractured, or different layers may have different strengths and stiffness.

Slopes that lose their vegetation to fire or drought are more vulnerable to landslides.

Massive slabs of rock crashed into homes in the village of Xinmo
Getty Images

Vegetation holds soil in place, and without the root systems of trees, bushes, and other plants, the land is more likely to slide away.

Utah experienced a devastating landslide brought on by heavy rains and rapidly melting snow wich caused a mass of earth 1,000 feet wide, 200 feet thick and one mile long to come loose.

Volcanic landslides are among the most devastating type of landslides.

The largest landslide in recorded history took place after the 1980 eruption of Mount St. Helens in Washington state, in the United States.

The resulting flow of ash, rock, soil, vegetation and water had a volume of 0.7 cubic miles, and covered an area of 24 square miles

Where has been hit recently?

  • Zante – Terrifying footage showed tourists trying to escape on boats as massive chunks of rock came crashing down on top of them in Navagio, Zante.
  • Japan – Sixteen people have been killed after a powerful earthquake rocked the island of Hokkaido triggering landslides that crushed homes and knocked out power.
  • Switzerland – Last year thirteen people were killed  in the Swiss village of Bondo after a massive landslide swept away a mountainside in the Alps, ripping apart buildings.
  • China – More than 100 people died after huge rocks and mounds of earth smashed into around 40 homes and a hotel in Xinmo at around 6am leaving one mile of road buried.

Which countries are prone to rockfalls and landslips?

Heavy rain heavy rain and steep mountains make for a potentially deadly combination for increasing the likelihood of landslides.

Remote regions in developing countries are particularly at risk from landslides because they lack of any sort of early-warning system.

South Carolina Governor Henry McMaster warned the US state could be hit by landslides – among other problems – as Hurricane Florence hit, bringing with it up to seven inches of rain.

Countries where there are frequent landslides include China, the western United States, Italy, Switzerland, Japan, the Philippines and Indonesia.

Countries that straddle the Himalayas such as Nepal, Pakistan and India are also areas where there are a large number of landslides.