Earthquakes are among the most devastating natural disasters on the planet. In the last hundred years they have claimed the lives of over one million people. Earthquakes are destructive mainly because of their unpredictable nature. It is impossible to say accurately when a quake will strike but a new theory could help save lives by preparing cities long in advance for an earthquake.
The surface of the Earth is made up of large 'tectonic' plates. These plates are in slow but constant motion. When two plates push against each other friction generates a great deal of energy. For this reason earthquakes occur most frequently on tectonic fault lines, where two plates meet. However these fault lines run for thousands of kilometres; predicting exactly where a quake will occur is nearly impossible.
In 1992, Dr Ross Stein was monitoring a large earthquake in a town in California called Landers. Three hours later, there was another quake 67km away at Great Bear. Stein believed that this was not simply an aftershock, instead he theorised the event at Landers had set off the earthquake at Big Bear. Stein believes that when an earthquake occurs the stress that has built up along the fault, is in part, transferred along the fault line. It is this energy transfer that causes other quakes to occur hours, days or months after the original.
Stein's team began to look for connections between the quakes in Landers and Big Bear. They had already been working on a computer model that could help them study the relationship between earthquakes. The data collected during the Landers/Big Bear quake had enabled them to create a model that could predict where the stress from Landers would have been transferred.
When they looked at the result the calculations did indeed show that the stress from Landers would have been transferred along the fault to Big Bear. They then plotted all of the subsequent 'aftershocks' and discovered that almost all occurred within a high-risk area they called a 'red zone'. This did not prove the theory of earthquake storms though. In order to do that the quakes would have to be triggered months or even years after the original earthquake.
Scientists from around the world were attracted by this new theory and there was one part of the world where it seemed from the available evidence that the earthquake storm theory might hold true.
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