Erosion is the action of surface processes that removes soil, rock, or dissolved material from one location on the Earth's crust and then transports it to another location where it is deposited. Erosion is distinct from weathering which involves no movement. Removal of rock or soil as clastic sediment is referred to as physical or mechanical erosion; this contrasts with chemical erosion, where soil or rock material is removed from an area by dissolution. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres.
Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, mudflows, shallow or deep-seated slope failures and debris flows. Landslides occur in a variety of environments, characterized by either steep or gentle slope gradients, from mountain ranges to coastal cliffs or even underwater, in which case they are called submarine landslides.
A slump is a form of mass wasting that occurs when a coherent mass of loosely consolidated materials or a rock layer moves a short distance down a slope. Movement is characterized by sliding along a concave-upward or planar surface. Causes of slumping include earthquake shocks, thorough wetting, freezing and thawing, undercutting, and loading of a slope.
Engineering geology is the application of geology to engineering study for the purpose of assuring that the geological factors regarding the location, design, construction, operation and maintenance of engineering works are recognized and accounted for. Engineering geologists provide geological and geotechnical recommendations, analysis, and design associated with human development and various types of structures. The realm of the engineering geologist is essentially in the area of earth-structure interactions, or investigation of how the earth or earth processes impact human made structures and human activities.
A geologic hazard or geohazard is an adverse of geologic condition capable of causing widespread damage or loss of property and life. These hazards are geological and environmental conditions and involve long-term or short-term geological processes. Geohazards can be relatively small features, but they can also attain huge dimensions and affect local and regional socio-economics to a large extent.
Mass wasting, also known as mass movement, is a general term for the movement of rock or soil down slopes under the force of gravity. It differs from other processes of erosion in that the debris transported by mass wasting is not entrained in a moving medium, such as water, wind, or ice. Types of mass wasting include creep, solifluction, rockfalls, debris flows, and landslides, each with its own characteristic features, and taking place over timescales from seconds to hundreds of years. Mass wasting occurs on both terrestrial and submarine slopes, and has been observed on Earth, Mars, Venus, Jupiter's moon Io, and on many other bodies in the Solar System.
A submarine canyon is a steep-sided valley cut into the seabed of the continental slope, sometimes extending well onto the continental shelf, having nearly vertical walls, and occasionally having canyon wall heights of up to 5 km (3 mi), from canyon floor to canyon rim, as with the Great Bahama Canyon. Just as above-sea-level canyons serve as channels for the flow of water across land, submarine canyons serve as channels for the flow of turbidity currents across the seafloor. Turbidity currents are flows of dense, sediment laden waters that are supplied by rivers, or generated on the seabed by storms, submarine landslides, earthquakes, and other soil disturbances. Turbidity currents travel down slope at great speed, eroding the continental slope and finally depositing sediment onto the abyssal plain, where the particles settle out.
A rockfall or rock-fall is a quantity/sheets of rock that has fallen freely from a cliff face. The term is also used for collapse of rock from roof or walls of mine or quarry workings. "A rockfall is a fragment of rock detached by sliding, toppling, or falling, that falls along a vertical or sub-vertical cliff, proceeds down slope by bouncing and flying along ballistic trajectories or by rolling on talus or debris slopes."
The Hilina Slump, on the south flank of the Kīlauea Volcano on the southeast coast of the Big Island of Hawaiʻi, is the most notable of several landslides that ring each of the Hawaiian Islands. These landslides are the means by which material deposited at a volcano's vents are transferred downward and seaward, eventually spilling onto the seabed to broaden the island.
A mudflow, also known as mudslide or mud flow, is a form of mass wasting involving fast-moving flow of debris and dirt that has become liquified by the addition of water. Such flows can move at speeds ranging from 3 meters/minute to 5 meters/second. Mudflows contain a significant proportion of clay, which makes them more fluid than debris flows, allowing them to travel farther and across lower slope angles. Both types of flow are generally mixtures of particles with a wide range of sizes, which typically become sorted by size upon deposition.
Rock glaciers are distinctive geomorphological landforms, consisting either of angular rock debris frozen in interstitial ice, former "true" glaciers overlain by a layer of talus, or something in-between. Rock glaciers are normally found at high latitudes and/or elevations, and may extend outward and downslope from talus cones, glaciers or terminal moraines of glaciers.
A Sturzstrom or rock avalanche is a large landslide consisting of soil and rock which travels a great horizontal distance compared to its initial vertical drop. Sturzstroms have similarities to the flow of glaciers, mudflows, and lava flows. They flow across land fairly easily, and their mobility increases when volume increases. They have been found on other bodies in the Solar System, including the Moon, Mars, Venus, Io, Callisto, Iapetus, and Phobos.
On February 17, 2006, a massive rock slide-debris avalanche occurred in the Philippine province of Southern Leyte, causing widespread damage and loss of life. The deadly landslide followed a 10-day period of heavy rain and a minor earthquake. The official death toll was 1,126.
There have been known various classifications of landslides. Broad definitions include forms of mass movement that narrower definitions exclude. For example, the McGraw-Hill Encyclopedia of Science and Technology distinguishes the following types of landslides:
Earth Revealed: Introductory Geology, originally titled Earth Revealed, is a 26-part video instructional series covering the processes and properties of the physical Earth, with particular attention given to the scientific theories underlying geological principles. The telecourse was produced by Intelecom and the Southern California Consortium, was funded by the Annenberg/CPB Project, and first aired on PBS in 1992 with the title Earth Revealed. All 26 episodes are hosted by Dr. James L. Sadd, professor of environmental science at Occidental College in Los Angeles, California.
Submarine landslides are marine landslides that transport sediment across the continental shelf and into the deep ocean. A submarine landslide is initiated when the downwards driving stress exceeds the resisting stress of the seafloor slope material, causing movements along one or more concave to planar rupture surfaces. Submarine landslides take place in a variety of different settings, including planes as low as 1°, and can cause significant damage to both life and property. Recent advances have been made in understanding the nature and processes of submarine landslides through the use of sidescan sonar and other seafloor mapping technology.
The West Salt Creek landslide occurred on the evening of May 25, 2014 near Collbran, Colorado, along the north side of the Grand Mesa, about 30 miles (48 km) east of Grand Junction. It was the largest landslide in Colorado's history.
The 2010 Mount Meager landslide was a large catastrophic debris avalanche that occurred in southwestern British Columbia, Canada, on August 6 at 3:27 a.m. PDT (UTC-7). More than 45,000,000 m3 (1.6×109 cu ft) of debris slid down Mount Meager, temporarily blocking Meager Creek and destroying local bridges, roads and equipment. It was one of the largest landslides in Canadian history and one of over 20 landslides to have occurred from the Mount Meager massif in the last 10,000 years.
Mount Cayley is an eroded but potentially active stratovolcano in the Pacific Ranges of southwestern British Columbia, Canada. Located 45 km (28 mi) north of Squamish and 24 km (15 mi) west of Whistler, the volcano resides on the edge of the Powder Mountain Icefield. It consists of massif that towers over the Cheakamus and Squamish river valleys. All major summits have elevations greater than 2,000 m (6,600 ft), Mount Cayley being the highest at 2,385 m (7,825 ft). The surrounding area has been inhabited by indigenous peoples for more than 7,000 years while geothermal exploration has taken place there for the last four decades.
A volcanic landslide or volcanogenic landslide is a type of mass wasting that takes place at volcanoes.
