Rock avalanche. The correct answer is D.
Rock avalanche are form of mass movement in which transported material is dry rock and fragmented either before or during slope failure. They are deep seated rock-slope failures consisting of rapid breakup of the failed rock mass with high velocities and long run-outs.
<h2>Further Explanation</h2>
Rock avalanche are large landslides from rock slopes that travel farther than smaller event.
It was first recognized in 19th century in Switzerland. It became known in Switzerland when the Elm and Goldau events killed people that are far away from the origin of the slide.
The Elm and Goldau events in Switzerland showed that rock avalanche has some characteristics: both events involve volumes of millions of cubic meters engaging large amount of energy and the travel distance both covered is very longer. Since these events, all rockslides relating to these peculiarities were categorized as rock avalanche, large rockslides or “sturzstorms”
Rock avalanche are very rare but then they are catastrophic events. It is more dangerous and deadly of all landslides events. In developing countries, rock avalanche causes high number of fatalities.
However, landslide refers to the movement of a mass rock, debris down a slope. It is triggered by heavy earthquake, heavy rainfall and many others.
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KEYWORDS:
- rock avalanche
- debris
- landslide
- slope
- rockslides
