Scientists have developed a new technique to monitor movements beneath the Earth's surface, helping them better understand how earthquakes behave.
The team, led by scientists Andrew Curtis, Heather Nicolson and David Halliday from the University of Edinburgh, says that the new method, which uses data collected from earthquakes in a new way, potentially allows the Earth's seismic activity to be mapped more comprehensively.
Scientists currently monitor underground movements, such as earthquakes and nuclear tests, using seismometers - instruments that measure the motion of those events at the Earth's surface. This helps to indicate where the events took place.
Now, by analysing the seismic waves produced during previous underground events, the team has been able to project how the site of each earthquake is affected by other earthquakes.. This has become possible by using earthquakes themselves as virtual seismometers that record passing waves from tremors that happen elsewhere in the world.
Using earthquakes in this way substantially increases the number of locations that could be used to detect seismic activity. And since earthquakes occur deep inside the earth, using them also allows scientists to monitor seismic activity from far deeper than previously possible.
Andrew Curtis, Professor of Mathematical Geoscience at the University of Edinburgh, said: "This turns the way we listen to seismic movements on its head. By using earthquakes themselves as virtual microphones which record the sound of the Earth's internal movements, we can listen to the Earth's stretching and cracking from directly within its most interesting, dynamic places."
The research, published in Nature Geoscience, was carried out in collaboration with the British Geological Survey and Utrecht University.
Dr Brian Baptie, Seismology Team Leader at the British Geological Survey, said: "This discovery shows how we can measure strains deep inside the Earth and helps improve our understanding of the processes driving earthquake activity."
The Earth's surface is tiled by tectonic plates that move constantly relative to each other. The picture shows one tectonic plate subducting (descending) beneath another. The plates rub together, stretch and crack, causing earthquakes in the deep Earth. The researchers use those earthquakes as virtual microphones, to record real sound waves from movements in the deep Earth. (Picture reproduced with permission from the British Geological Survey).
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This article was published on Sep 1, 2010