Which of the following is the major contributing factor in all landslides?

stream erosion

precipitation

earthquakes

gravity

sedimentary layers oriented parallel to the slope

precipitation

Explanation:

The landslides are mass movements. They are very dangerous, as they occur suddenly, have very big force, move in high speeds, have numerous materials in them, and usually are able to destroy everything on their way. The prime reason for any landslide to occur is the precipitation. To be more specific, enormous amounts of precipitation in a very short period of time. The water from the intensive rainfall will over-saturate the ground. As it does, the upper layer of the soil will start to bubble up and once the pressure from its wight is too much, the water moves it downwards. The combination of ground, water, rocks, biomass, is very deadly, and usually everyone that is caught by it ends up dead unfortunately.