What?

A 7.0 magnitude earthquake

When?

12th January 2010 at 16.53 local time (21.53 GMT).

Where?

The earthquake occurred 18.457°N, 72.533°W. The focus of the earthquake was 13km (8.1 miles) below the surface of the earth.

Why?

Haiti is situated to the north of the Caribbean Plate, on a transform (slip/conservative) plate boundary with the North American Plate. The North American plate is moving west. This movement is not smooth and there is friction between the North American Plate and the Caribbean Plate. Pressure builds between the two plates until it is released as an earthquake.

A map to show the location of Haiti in relation to tectonic plates. Source BBC.

The epicenter of the earthquake was 16km south west of Port-Au-Prince. The earthquake was caused by a slip along an existing fault in this area (Enriquillo-Plaintain Garden fault).

A map to show the location of the epicentre of the earthquake

So What?

As of Feb. 12, an estimated three million people were affected by the quake; the Haitian Government reports that between 217,000 and 230,000 people had been identified as dead, an estimated 300,000 injured, and an estimated 1,000,000 homeless. The death toll is expected to rise.They also estimated that 250,000 residences and 30,000 commercial buildings had collapsed or were severely damaged.

So, why did so many people die in the Haiti earthquake? There are a number of reasons for this:

1. The earthquake occurred at shallow depth – this means that the seismic waves have to travel a smaller distance through the earth to reach the surface so maintain more of their energy.
2. The earthquake struck in the most densely populated area of the country.
3. Haiti is the poorest country in the Western Hemisphere
4. The buildings in Port-Au-Prince and other areas of Haiti were in very poor condition in general and were not designed or constructed to be earthquake resistant.
5. 3 Million people live in Port au Prince with the majority living in slum conditions after rapid urbanisation.
6. Haiti only has one airport with one runway. The control tower was badly damaged in the earthquake. The port is also unusable due to damage.
7. Initially, aid had been piling up at the airport due to a lack of trucks and people to distribute it. Water and food have taken days to arrive and there is not enough to go around.
8. Rescue teams from around the world took up to 48 hours to arrive in Haiti due to the problems at the airport. Local people have had to use their bare hands to try and dig people out of the rubble.
9. There has been a severe shortage of doctors and many people have died of injuries such as broken limbs.

Web Links

 The BBC news web site has a comprehensive overview of the earthquake here. The BBC have produced an excellent article titled Why did so many people die in the Haiti earthquake? and provides comparative data with similar size earthquakes.