Liquid water is the major agent of erosion on Earth. Rain, rivers, floods, lakes, and the ocean carry away bits of soil and sand and slowly wash away the sediment. Rainfall produces four types of soil erosion: splash erosion, sheet erosion, rill erosion, and gully erosion.

Creep is a very slow mass movement that goes on for years or even centuries. You can’t see creep happening but leaning fences and poles and broken retaining walls show where it has taken place.

Creep Creep is the very slow downhill movement of rock and soil. It can even occur on gentle slopes. Creep often results from the freezing and thawing of water in cracked layers of rock beneath the soil.

Surface creep is the slow downhill movement of soil and rock debris. The term can also describe the rolling of soil particles by wind along soil surface.

Triggered by earthquake shock or torrential rain in mountainous relief with steep gradients, a huge volume of avalanching rock or debris (of up to millions of metric tons) can reach a velocity of more than 50 metres (160 feet) per second and leave a long trail of destruction.

Such factors include: weathering or erosional debris cover on slopes, which is usually liable to mass movement; the character and structure of rocks, such as resistant permeable beds prone to sliding because of underlying impermeable rocks; the removal of the vegetation cover, which increases the slope’s susceptibility …

Landslides and avalanches are the most dramatic, sudden, and dangerous examples of earth materials moved by gravity. Landslides are sudden falls of rock, whereas avalanches are sudden falls of snow.

In areas of very steep slopes they can reach speeds of over 100 miles per hour (160 km/hour). However, many debris flows are very slow, creeping down slopes by slow internal movements at speeds of just one or two feet per year (30 to 60 centimeters per year).

You can’t stop or change the path of a debris flow. However, you may be able to protect your property from floodwaters or mud by use of sandbags, retaining walls or k-rails (Jersey barriers). In mud and debris flow areas, consider building channels or deflection walls to try to direct the flow around buildings.

Debris flows are fast-moving landslides that are particularly dangerous to life and property because they move quickly, destroy objects in their paths, and often strike without warning. Debris flows can travel at speeds up to and exceeding 35 mph and can carry large items such as boulders, trees, and cars.

The speed of a debris flow may reach 100 miles per hour, although most commonly they are slow and move only a few feet per year downslope. A mud slide or mud flow is a mass of water and fine-grained earth materials that flows down a stream, ravine, canyon, arroyo, or gulch.

It’s lumpy, lobe-shaped, and rocky. It’s muddy, lobe-shaped, and smooth. It has scarps near the top and a rounded, lumpy lower end.

Mudflows contain a significant proportion of clay, which makes them more fluid than debris flows; thus, they are able to travel farther and across lower slope angles. Mudflows often start as slides, becoming flows as water is entrained along the flow path; such events are often called flow slides.

Gravity is the main force responsible for mass movements. Gravity is a force that acts everywhere on the Earth’s surface, pulling everything in a direction toward the center of the Earth.

Gradient also influences mass movement. Gradient refers to slope. When the slope is steep it is more likely that mass movement will occur.

Mudflow deposits are poorly sorted mixtures of silt, boulders, organic materials, and other debris. They have abrupt and well-defined edges, irregular surfaces, and a lobate appearance; they may be 3 to 6 m (10 to 20 feet) high. Such deposits are extensive on alluvial fans and around the bases of many volcanoes.

How do you protect your home or building from mudslides?

1. Vegetation is a great defense against mudslides.
2. Retaining walls can also prevent mudslides and mudslide damage.
3. Channels, diversion barriers, and deflection walls can help redirect the flow away from property.

Creep is a very slow mass movement that goes on for years or even centuries. Terracettes are built by soil creep. The process is sped up by animals walking along the tops of the terracettes. When sediment. expands, individual particles are lifted up at right angles to the slope.

Try to avoid construction and staying in vulnerable areas. Do not panic and loose energy by crying. Do not touch or walk over loose material and electrical wiring or pole. Do not built houses near steep slopes and near drainage path.

Mount St. Helens

Deadliest Landslides In Recorded History

• Kelud Lahars, East Java, Indonesia, May 1919 (5,000+ deaths)
• Huaraz Debris Flows, Ancash, Peru, December 1941 (5,000 deaths)
• 62 Nevado Huascaran Debris Fall, Ranrahirca, Peru, January 1962 (4,500 deaths)
• Khait Landslide, Tajikstan, July 1949 (4,000 deaths))
• Diexi Slides, Sichuan, China, August 1933 (3,000+ deaths)

Debris flows are geological phenomena in which water-laden masses of soil and fragmented rock rush down mountainsides, funnel into stream channels, entrain objects in their paths, and form thick, muddy deposits on valley floors.

A debris flow is the movement of a water-laden mass of loose mud, sand, soil, rock and debris down a slope. A debris flow can dash down the slope, reaching speeds of 100 miles per hour or greater. An earthflow is a flow of fine-grained material that typically develops at the lower end of a slope.