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Last updated at 16:59 BST, Thursday, 01 April 2010

Earthquake science

Summary

5 April 2010

A team of scientists say they can explain why many more people died in the earthquake in Haiti compared to the much larger quake in Chile.

Reporter:
Gideon Long

Earthquake damage in Chile

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Report

The geophysicists, from the U.S. Geological Survey and from Harvard University, said that strict building regulations in Chile had undoubtedly saved lives. The country has a long history of earthquakes and as a consequence has some of the toughest building codes in the world.

But Doctor Walter Mooney, who's studied dozens of earthquakes around the globe, said there were also other factors behind the relatively low death toll.

Walter Mooney:
"First and foremost, people are used to earthquakes in Chile and so they did know that they have to evacuate from dangerous structures Secondly, this earthquake had a slow and gradual build-up. They had some 20 or 30 seconds to look at each other, realize that the ground shaking was crescendoing, and building up, and they made the right decision in almost all cases by getting out of the dangerous structures and running out into the open area. So, education, and a bit of luck is the answer to why so many people survived."

Doctor Mooney contrasted that with the Haitian quake, which split open the hard rock beneath the capital Port Au Prince within seconds. Buildings collapsed instantly, giving people no time to escape.

Despite the relatively low loss of life in Chile, Dr Mooney said the country must learn from this disaster, particularly with regards to building along the coast. Many of those who died were killed not by the quake, but by the tsunamis that followed it, which swept away coastal villages.

And the geophysicists said that even if Chile took precautions, it would remain highly vulnerable to earthquakes. They said that the north of the country was a particular worry. It hasn't suffered a big quake for around a hundred years and is probably due for one soon, they said.

Gideon Long, BBC, Chile

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Vocabulary

geophysicists

scientists who study the forces that cause movement within parts of the earth

strict building regulations

strong rules and laws which say how buildings must be built

as a consequence

because of this

factors

reasons

death toll

total number of people who died

to evacuate from

to leave, to get out of

crescendoing

getting more powerful

tsunamis

huge waves caused by the movement in the ground of the earthquake

remain highly vulnerable to

have a very high chance that it would happen again