Earthquakes are the result of forces deep within the earth's interior. Sudden break within the upper layers of the earth, sometimes breaking the surface, resulting in the vibration of the ground, which where strong enough will cause the collapse of buildings and destruction of life and property.

They strike with no early warning and can be devastating, but after a major one, aftershocks may be as strong as a new earthquake. Earthquakes usually happens along a fault plate, the border between plates:

Global plate tectonic map (click to enlarge the map)

Earthquakes often trigger landslides, tidal waves and tsunamis. Powerful aftershocks frequently occur, causing further damage and increasing psychological stress.

When earthquakes hit, local Red Cross Red Crescent volunteers carry out search and rescue - this is more effective than rescue teams who are flown in from abroad as these teams generally arrive too late. High numbers of seriously injured people may require surgery within 48-72 hours, after that little lifesaving surgery can be done.

After an earthquake, the Federation response prioritizes first aid, shelter, safe water and sanitation, basic health care and field hospitals. Psychological support should always be addressed, as well as possible tracing mechanisms for reuniting families.

Measuring earthquakes

Intensity scales, like the Modified Mercalli scale and the Rossi-Forel scale, measure the amount of shaking at a particular location. So the intensity of an earthquake will vary depending on where you are. Sometimes earthquakes are referred to by the maximum intensity they produce.

Magnitude scales, like the Richter magnitude scale and moment magnitude, measure the size of the earthquake at its source. So they do not depend on where the measurement is made. Often, several slightly different magnitudes are reported for an earthquake. This happens because the relation between the seismic measurements and the magnitude is complex and different procedures will often give slightly different magnitudes for the same earthquake.

Earthquakes are measured according to the Richter scale - the most devastating effects are seen on level 6 and above, and if the epicentre of the earthquake is located in highly populated areas. Earthquakes can cause high numbers of deaths and injuries as well as serious destruction of buildings and infrastructure.

How to prevent

You cannot prevent earthquakes but you can reduce the potential damages:

  • Development of possible warning indicators.
  • Land-use regulations.
  • Building regulations.
  • Relocation of communities.
  • Public awareness and education programs.

Documents available:

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Related Red Cross / Red Crescent operations: