Slope failure: Extent and economic significance in Afghanistan and Pakistan

The complex geology of Afghanistan and Pakistan is a mosaic of sutured and uplifted crustal fragments whose widely varying rock types, great relief and high seismicity cause many slope failures. Rock falls and rock slides are among the most common failure types in the Hindu Kush and western Himalayas; one large sackung failure has also been recognized. Debris falls and debris slides from the many deposits of rubble and regolith are common; catastrophic debris flows are frequent during monsoon rains. Earth falls, earth slides and earth flows are least common but do occur in loess and clay-rich saprolites. Large complex slump-and-f1ow landslips occur in unstable sedimentary rock in a few places in northern Afghanistan. Many of these different landslips have repeatedly destroyed highways, homes and water works, as well as damming rivers and causing later break-out floods. Slope-failure hazards are an important constraint on development in the two countries, although little data on monetary or human losses are collected as yet.