Various methods can be used to reduce or protect people from mass movements. In addition, some methods are meant to stabilise and lessen slope stress which mitigate mass movements altogether.
However, note that most methods of handling mass movements are meant to reduce their impact or slow them down rather than completely preventing them from happening. Relocation from unstable slopes is the best prevention method against mass movements.
Prevention /Mitigation Methods
Terracing
Terracing involves the shaping of slopes into steps. When mass movements occur the waste is captured and accumulates on the flat steps and impeded from readily sliding or flowing down the slope.
Afforestation
Trees bind the soil from moving, and can also intercept and slow down mass movements, e.g earthflows.
Wedging/ Deflection Walls
Wedges are strong walls or objects that redirect mass movements to other areas. The main purpose of wedges is to protect a particular area from mass movements such as mudflows or avalanches.
Drainage Controls
Water adds more weight to the soil.
By observing drainage patterns and routes, streams can be diverted to restrict water from vulnerable slope areas
Pipes can be inserted along the slope so that water readily leaves the slope which prevents soil liquefaction.
Artificial channels can direct watery flows away from houses, and storm drains help remove excess water from the surface.
Relocation
Relocating settlements away from unstable slopes is the best prevention method from mass movements. However, inadequate funding and resistance to move can hinder progress.
Slope Stabilization Methods
These methods involve stabilizing and reducing stress and strain on the slope which mitigates mass movements
Afforestation
Trees help to bind the soil together and stabilize slope movement.
Geomats
Geomats are synthetic nets that are embedded on a surface to avoid excess soil movement and reduce rainsplash impact.
Slope Leveling
Leveling slopes means flattening and grading slopes to reduce mass movements.
Bolts/Nails
Rocky slopes can be nailed along cracks or failure planes to stabilise movements.
Cementing/Shotcrete
Fractures along the slope can be plastered with cement to stabilise movement.
Protection Methods
Methods to protect people from mass movements
- Retaining walls on slope foot
- Wire nets on slope base
- Base trenches to capture rock falls
- Wedges/ Divergent wall to redirect mass movements
Warnings
- Springs, seeps, or saturated ground in areas that have not typically been wet before.
- New cracks or unusual bulges in the ground, street pavements or sidewalks.
- Soil moving away from foundations.
- Ancillary structures such as decks and patios tilting and/or moving relative to the main house.
- Tilting or cracking of concrete floors and foundations.
- Broken water lines and other underground utilities.
- Leaning telephone poles, trees, retaining walls or fences.
- Offset fence lines.
- Sunken or down-dropped road beds.
- Rapid increase in creek water levels, possibly accompanied by increased turbidity (soil content).
- Sudden decrease in creek water levels though rain is still falling or just recently stopped.
- Sticking doors and windows, and visible open spaces indicating jambs and frames out of plumb.
- A faint rumbling sound that increases in volume is noticeable as the landslide nears.
- Unusual sounds, such as trees cracking or boulders knocking together, might indicate moving debris.
