title: Earthquakes

photo: earthquake damageNatural disasters such as earthquakes have been studied for many years. The Richter scale gives a mathematical measurement of an earthquake's size, or "magnitude". It can be used to indicate how destructive an earthquake is.


The Richter scale can be used to look at the hazard an earthquake may pose.


Richter magnitude scale
Earthquake effects

Up to 3.5

Recorded by seismic sensors but usually not felt by people.


Can be felt by people. Slight vibrations of buildings and movement of hanging lights. No real damage to well-constructed buildings.

Under 6.0

Rattling and movement of objects inside buildings. Slight damage such as cracks in walls of well-constructed buildings.Can cause major damage to poorly-constructed buildings could lead to casualties or deaths.


Can be destructive in areas up to about 100 kilometers
across where people live. Serious damage to well-constructed buildings. Collapse of poorly-made buildings over a confined area. Possible human casualties and deaths.


Major earthquake. Serious damage and collapse of buildings over over larger areas. Increasing hazard of casualties and deaths.

8 or greater

Great earthquake. Collapse of buildings over a region of several
hundred kilometers. Possibility of large numbers of casualties and deaths.

The risk from earthquakes will also depend on the part of the world and also the population in that area. In the United Kingdom, large earthquakes are very rare. In the Pacific rim they are much more common so are a greater risk in areas like Asia and the West Coast of the Americas).