A cave-in is a collapse of a geologic formation, mine or structure which may occur during

mining Mining is the Resource extraction, extraction of valuable geological materials and minerals from the surface of the Earth. Mining is required to obtain most materials that cannot be grown through agriculture, agricultural processes, or feasib ...

tunnel A tunnel is an underground or undersea passageway. It is dug through surrounding soil, earth or rock, or laid under water, and is usually completely enclosed except for the two portals common at each end, though there may be access and ve ...

ing, or steep-walled excavation such as trenching. Geologic structures prone to spontaneous cave-ins include

alvar An alvar is a biological environment based on a limestone plain with thin or no soil and, as a result, sparse grassland vegetation. Often flooded in the spring, and affected by drought in midsummer, alvars support a distinctive group of prairie ...

, tsingy and other limestone formations, but can also include

lava tube A lava tube, more rarely called a pyroduct, is a 'roofed conduit through which molten lava travels away from its vent'. If lava in the tube drains out, it will leave an empty cave. Lava tubes are common in low-viscosity volcanic systems. La ...

s and a variety of other subsurface rock formations.

Glacier cave A glacier cave is a cave formed within the ice of a glacier. Glacier caves are often called ice caves, but the latter term is properly used to describe bedrock caves that contain year-round ice. Overview Glacier caves form in the bottom edge ...

s and other ice formations are very prone to collapse from exposure to warm temperatures or running water. In mining, the term roof fall is used to refer to many types of collapses, ranging from the fall of a single flake of

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...

to collapses that form sink holes that reach to the surface. However, roof falls in mining are not all accidental. In

longwall mining Longwall mining is a form of underground coal mining where a long wall of coal is mined in a single slice (typically thick). The section of rock that is being mined, known as the longwall panel, is typically long, but can be up to long and wi ...

and retreat mining, miners systematically remove all support from under large areas of the mine roof, allowing it to settle just beyond the work area. The goal in such mining methods is not to prevent roof fall and the ensuing surface

subsidence Subsidence is a general term for downward vertical movement of the Earth's surface, which can be caused by both natural processes and human activities. Subsidence involves little or no horizontal movement, which distinguishes it from slope mov ...

, but rather to control it.

Geological formations

Alvar An alvar is a biological environment based on a limestone plain with thin or no soil and, as a result, sparse grassland vegetation. Often flooded in the spring, and affected by drought in midsummer, alvars support a distinctive group of prairie ...

structures such as on the

Stora Alvaret Stora Alvaret (; "the Great Alvar") is an alvar, a barren limestone terrace, in the southern half of the island of Öland, Sweden. Stora Alvaret is a dagger shaped expanse almost long and about at the widest north end. The area of this formatio ...

Öland Öland (, ; ; sometimes written ''Oland'' internationally) is the second-largest Swedish island and the smallest of the traditional provinces of Sweden. Öland has an area of and is located in the Baltic Sea just off the coast of Småland. ...

Sweden Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...

Karst Karst () is a topography formed from the dissolution of soluble carbonate rocks such as limestone and Dolomite (rock), dolomite. It is characterized by features like poljes above and drainage systems with sinkholes and caves underground. Ther ...

limestone such as in the

Madagascar dry deciduous forests The Madagascar dry deciduous forests represent a tropical and subtropical dry broadleaf forests, tropical dry forest ecoregion situated in the western and northern part of Madagascar. The area has high numbers of Endemism, endemic plant and anima ...

References

Caves Mining terminology {{mining-stub