rockslides

Rockslides are a form of rapid mass wasting in which a relatively coherent block of bedrock moves downslope along a failure surface. The moving mass typically remains largely intact, contrasting with rockfalls, which involve disintegration and free-fall. Rockslides may be translational, sliding along a planar surface, or rotational, along a curved surface. They can reach high velocities, and volumes range from thousands to millions of cubic meters, with runouts that depend on terrain and rock type.

Causes and triggers include weakening of the rock mass by weathering, fracturing, and faulting, combined with destabilizing forces such as undercutting, heavy rainfall or rapid snowmelt that increase pore pressure, seismic shaking, and thawing of permafrost. Human activities like mining, road construction, or blasting can also trigger or accelerate rockslides. Preexisting joints, bedding planes, and lithology largely govern where slides occur.

Hazards and impacts: Rockslides can bury or destroy roads, buildings, and utilities, and can dam rivers, creating temporary lakes that may breach catastrophically. In mountainous regions, debris can dislodge, generating secondary hazards such as rockfalls and debris flows when water is involved. Risk is highest where slopes are steep, weakly cemented, or heavily fractured.

Mitigation and monitoring: Approaches include slope stabilization (rock bolts, nets, shotcrete), drainage improvement to reduce pore pressure, and removal or confinement of unstable blocks. Early warning systems, ground-based sensors, and satellite monitoring help detect precursors. Access restrictions and designated safe zones are common public safety measures in high-risk areas.