Sesuvy

Sesuvy are gravity-driven mass movements that involve the downslope movement of soil, regolith, and rock along slopes. They occur in natural and human-altered landscapes and can range from small, slow slides to large, rapid flows that cover long distances. Movement may take the form of coherent slides (translational or rotational) or as debris and earth flows, with occasional rock falls or slumps. The term sesuv is used in Central European languages to denote this broad category of slope instability.

Causes and triggers include a combination of long-term factors and short-term events. Weak or fractured bedrock, anomalous pore-water pressures, and undercutting of the slope by erosion or construction raise instability. Trigger mechanisms often involve heavy or prolonged rainfall, rapid snowmelt, earthquakes, dewatering or drainage changes, freeze-thaw cycles, and vegetation removal or land-use changes that reduce slope stabilization.

Common types of sesuvy are rock slides, debris slides, rock and debris flows, earthflows, and slumps. Debris flows are particularly hazardous in valleys because they mix water with unstable material and can transform into fast, fluid-like flows that travel far from the source.

Hazards from sesuvy activity include destruction of roads, buildings, and utilities; disruption of transportation networks; changes to drainage and river channels; and long-term landscape alteration. Early warning and monitoring use rainfall thresholds, ground surveys, lidar or InSAR imagery, and surface deformity measurements. Mitigation measures emphasize slope stabilization (drainage control, retaining structures, soil nails), controlled vegetation, land-use planning, and, where feasible, undercutting and redirection of mass movement paths.