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Earthquake early warning

Earthquake early warningNearly 300,000 people were killed as a result of the Indian Ocean earthquake on Boxing Day 2004. Since then scientists have been trying to find ways to predict when earthquakes will take place.

The earthquake of 2004 caused a series of tsunamis (huge waves) which killed hundreds of thousands of people. If we can find a way to predict earthquakes further in advance, then local people can be warned, so preventing loss of life on this level again.

Swedish seismologists (earthquake experts) may have found a new method to show when and where earthquakes will occur. They have looked back over information from the Indian Ocean five years before the catastrophe happened to see if they could find a pattern.

In the area around Sumatra and, the Andaman and Nicobar Islands earthquakes are common. The tension created in the area when continental plates rub against each other produces a number of minor earthquakes a few years before the big earthquake comes.

During the five years looked at by the scientists there were 624 quakes in the area. On October 24th, 2002, a powerful earthquake was registered at 7.1 on the Richter scale, and on September 13th the same year there was a 6.7 quake. The earthquake that caused the tsunami disaster measured 9.0 on the Richter scale.

Scientists from the Swedish Defense Research Agency (FOI) have studied how the activity in the crust of the earth changed before these tremors.
They looked at how the quakes were distributed in time and space within the area. The researchers used the relation between major and minor quakes, the so-called b-value. The lower the b-value, the greater the increase in tension in the earth’s crust, which meant a greater risk of major quakes.

Lead researcher, Leif Persson explained:

"We found that all of the major tremors were clearly visible in a time perspective. The b-value dropped drastically before the big quakes."

This research shows that there is a sign-post pointing the way to large earthquakes, and using this method it will hopefully be possible to predict when and where an event of this scale will happen again.

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