Transcript Hazardous Environments resulting from Mass Movements

Hazardous Environments
resulting from Mass Movements
Mass movements take place when shear stress
(the force trying to move the material) is greater
than shear strength (the strength or resistance
of the slope).
Shear stress> shear strength
Causes of Mass Movement
Movement is determined by:
• Gravity
• Slope angle
• Pore pressure
Hazardous mass movements
• Landslides
• Mudslides
• Avalanches
landslides
Triggered by
• Seismic activity
• Heavy rainfall
• Human activity
• Case studies of the Caribbean
• Case study of Puerto Rico
• Case study of China
mudslides
Triggered by
• Human causes – uncontrolled building,
creation of impermeable surfaces,
deforestation, burning.
• Heavy rainfall
• Tectonic activity
• Case studies – Italy 1998, Venezuela
avalanche
Mass movement of ice and snow
Triggered by:
• Newly fallen snow falling off older snow
• Partially thawed snow in spring
• Steep slopes
• North-facing slopes (NH)
Classification of avalanche:
• Type of breakaway
• Position of sliding surface
• Water content
• Form of avalanche – open or channelled.
• Case studies – Europe 1999.