HKDSE Geography/E1/Geological Hazards

Geological hazards include landslides, mudflows, earthflows, avalanches. Landslides are discussed here.

The two worst landslides in Hong Kong are the Sau Mau Ping landslide (71 killed) and the Po Shan landslide (67 killed).

Distrubution
Landslides exhibit clear temporal and spatial distribution.

Temporal
Landslides concentrate in summer. About 78% of Hong Kong's rainfall falls in summer. Wet southeasterly monsoons and typhoons bring rainstorms from the ocean. (See E2)

Spatial
Landslides occur more often on granite slopes than tuff slopes. Granite slopes have lower resistance. They are more prone to weathering, so they are disintegrated into smaller fragments and particles. The internal cohesion of the slope materials is weaker. Also, more granite slopes have gone through human development than tuff slopes. For example, the two sides of Victoria Harbour, an exposed granite batholith, has gone through the most urban development. This leads to more landslides, discussed on the next page.