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Earth Oddities Hub
Landslides and mass movements occur when gravity sends rock, soil, mud, snow or ice downslope.
Some slopes creep almost imperceptibly for decades. Others collapse in seconds, releasing destructive
mudslides, falling boulders, rock avalanches or torrents of snow and ice.
Explore how unstable slopes fail, what triggers sudden movement, why some events travel for kilometers,
which warning signs matter and how landslide and avalanche risks are monitored and reduced.
Which Guide Should You Read?
| Phenomenon | Primary material | Best guide |
|---|---|---|
| Landslide, slope failure or slump | Soil, earth, debris or mixed material |
Landslides & Mudslides |
| Mudslide, mudflow or debris flow | Water, mud, rocks and vegetation |
Landslides & Mudslides |
| Earthflow, slope creep or slow deformation | Fine soil, weathered rock or earth |
Landslides & Mudslides |
| Rockfall or falling boulder | Bedrock and detached rock blocks |
Rockfalls & Rock Avalanches |
| Rockslide, cliff collapse or mountain collapse | Coherent or fragmented bedrock |
Rockfalls & Rock Avalanches |
| Snow avalanche | Dry, wet or wind-loaded snow |
Snow & Ice Avalanches |
| Ice or glacier avalanche | Glacier ice, seracs and snow |
Snow & Ice Avalanches |
| Rock–ice avalanche | Bedrock, glacier ice and snow |
Rockfalls & Rock Avalanches or Snow & Ice Avalanches , depending on the dominant material |
What Triggers Mass Movements?
Gravity drives every mass movement, but failure usually begins when a slope is weakened or rapidly loaded.
Common triggers include:
- intense or prolonged rainfall;
- groundwater pressure and rapid snowmelt;
- earthquake shaking;
- freeze–thaw weathering;
- river and coastal erosion;
- wildfires and vegetation loss;
- glacier retreat and mountain-permafrost thaw;
- volcanic activity;
- excavation, mining, construction and altered drainage;
- new snowfall, wind loading, warming and rain-on-snow.
The visible trigger is often only the final push. Many slopes and snowpacks weaken gradually before suddenly
crossing the threshold between stability and movement.
Related Earth Oddities
-
Sinkholes & Land Subsidence
— Vertical ground collapse, subsidence, fissures, thermokarst and loss of underground support. -
Earthquakes
— Seismic shaking, fault rupture and earthquake-triggered slope failures. -
Volcanoes
— Volcanic flank collapse, debris avalanches, lahars and eruption-related instability. -
Geology
— Rock structure, weathering, erosion, tectonics and the forces shaping Earth’s surface. -
Ocean & Coastal Phenomena
— Coastal erosion, collapsing sea cliffs and landslide-generated displacement waves.
