Geological hazards of our earth

Types of Geological hazards

A geologic hazard  has been defined as an extreme natural events in the crust of the earth that pose a threat to life and property, for example, earthquakes, volcanic eruptions, tsunamis (tidal waves) and landslides.

(OECD Glossary of Statistical Terms – Geologic hazard Definition › glossary › detail)

Major natural disasters

Using the definition above linking to the crust of the earth, there is a link to the major global natural disasters affecting life and property. Lightning causing death and fire is a natural phenomenon that in extreme situations be generated by large fire fronts.

  • 7 Landslides.
  • 6 Volcanic eruptions.
  • 5 Tornadoes.
  • 4 Lightning.
  • 3 Tsunamis.
  • 2 Hurricanes.
  • 1 Earthquakes.

Of the major natural disasters listed above the effects some can be greatly exacerbated by human activity.  For example landslides and land slips  usually occur when hydrological (water saturation of a rock and soil) loading of the soil and rock mass on steep slopes is excessive.  If these slopes have also been cleared or partially so due to human activities (including agriculture and mining) the landslide can be far more destructive as the rock and soil mass becomes over saturated and will form a sheet like dense flow carrying thick mud and rocks and burying all in its path.  There are numerous examples of this occurring in Latin America. Major landslips can occur im regions that have an unstable substrate such as regions affected by the movement of ice across a landscape that can create clays that can liquefy whne saturated to form a glide plane for large areas of land such as the one in Norway in early June 2020