Key Themes: Geohazards

The 'Key Themes' posts are a series of short articles outlining the role that geologists have in various aspects of global development.


Communities across the world are affected by geohazards of one form or another. Earthquakes, volcanoes, landslides, floods, and tsunamis are all hazards that can and have led to severe damage, loss of life and devastation for communities large and small. Other hazards such as tropical storms, droughts, and wildfires can also cause misery for many.

When natural hazards occur in populated places that are vulnerable to natural hazards they can result in a natural disaster. An earthquake occurring in an unpopulated area is not considered to be a natural disaster, whereas when a hazard meets vulnerability, such as the 2011 New Zealand earthquake occurring in the heavily built-up and populated Christchurch area, it is considered to be a natural disaster.

Damage to Christchurch Cathedral
From Gabriel,
www.flickr.com/photos/47407357@N07/5472981231

Disasters can result in all or some of, (1) Injury and loss of life; (2) Damage to buildings and structures; (3) Loss of crops, food and drinking water supplies. Often the initial hazard triggers or raises the probability (through increasing vulnerability) of other hazards, which will cause further damage and loss. An example of this can be seen by studying the Haiti earthquake, where damage not only occurred from the earthquake but also later cholera outbreaks due to poor water and sanitation conditions. In New Zealand some of the damage and fatalities were a result of seismically induced landslides.

Pakistan Floods
From: www.defenseimagery.mil/imagery.html#guid=
730d602e84cbb5b33869eee5ec814a81dc0bdd74

Natural disasters are in the news on a regular basis. The recent earthquake in New Zealand caused severe damage to the city of Christchurch, as well as loss of life. In the past year or so there have been landslides and floods in Brazil and Bolivia, severe flooding in Pakistan and Australia, and volcanic eruptions in the Philippines. Not to mention the large earthquakes in Chile and Haiti. This is by no means an exhaustive list of natural disasters in the 2010-2011 period.

Geohazards are a fundamental part of our world, and billions across the world are forced to live and work alongside them. Many organisations are working to better understand these hazards and reduce the vulnerability to them, in doing so reducing the level of disaster.

What role do geologists have to play in this sector?

Geologists have a crucial role in studying and analysing the causes, mechanisms and impacts of geohazards. Geologists use their field skills to examine areas, which are prone to, for example, earthquakes. Their fieldwork can be used to help determine the mechanism by which they occur, the frequency they occur and areas of ground that will be affected to a greater or lesser extent by an earthquake. In a similar way, geologists can also use their field skills to monitor and study volcanoes and landslide prone areas.

Greece: Fault Analysis

Geologists can also use their analytical skills, often combined with information from the field, to determine the probability of specific sized events occurring, within a given area – such as the probability of a Magnitude 8 or greater earthquake in an area. This information can be used to generate hazard maps, inform the insurance industry, and help communities adapt to reduce the impact of the hazard.