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:

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 prioritises 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.
  

Volcanic eruptions happen when lava and gas are discharged from a volcanic vent. The most common consequences of this are population movements as large numbers of people are often forced to flee the moving lava flow. Volcanic eruptions often cause temporary food shortages and volcanic ash landslides called Lahar. The most dangerous type of volcanic eruption is referred to as a 'glowing avalanche'. This is when freshly erupted magma forms hot pyroclastic flow which have temperatures of up to 1,200 degrees. The pyroclastic flow is formed from rock fragments following a volcanic explosion , the flow surges down the flanks of the volcano at speeds of up to several hundred kilometres per hour, to distances often up to 10km and occasionally as far as 40 km from the original disaster site.

The International Federation response adjusts to meet the needs of each specific circumstance. As population movement is often a consequence, the provision of safe areas, shelter, water, food and health supplies are primordial. In general response prioritizes temporary shelter materials; safe water and basic sanitation; food supplies; and the short term provision of basic health services and supplies.