What Does it Mean Block Slumping?

Block slumping

Rocks falling in blocks along a steep slope or cliff, or slipping away from the entire site of a mass.

Block slumping refers to a type of mass movement or landslide where a large section of earth or rock breaks away and slides down a slope in a relatively coherent and intact manner. This process typically occurs on sloped surfaces and is influenced by factors such as gravity, water saturation, and weak underlying materials.

Characteristics of Block Slumping:

1. Coherent Movement: The material often moves as a single large block, maintaining its structure as it slides or rotates.
2. Rotational Movement: The block may rotate along a curved surface, creating a "slump scarp" (a steep face at the top) and a "toe" (the lower part where the material piles up).
3. Triggers:
   • Water Saturation: Heavy rain or groundwater can weaken the slope's stability.
   • Erosion: Undercutting by rivers or waves removes support from the base of a slope.
   • Human Activity: Excavation or deforestation can destabilize slopes.
4. Common Locations:
   • Coastal cliffs.
   • Riverbanks.
   • Hillsides with clay-rich soils, which are prone to sliding when wet.

Example:

Imagine a hillside with soft clay layers at the base. After heavy rainfall, the saturated clay becomes weak, causing a large block of overlying soil and rock to slump downward.