Eye in the sky spies earthquakes | University of Oxford
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OSB archive

Eye in the sky spies earthquakes

Pete Wilton

Orbiting satellites can provide crucial evidence for what's happening deep beneath the earth, as this American Scientist article reports.

In the piece Richard Walters, of Oxford's Department of Earth Sciences, describes how his team used radar data from ESA's Environmental Satellite (ENVISAT) to study the recent L'Aquila earthquake.

They used a technique called Interferometric Synthetic Aperture Radar (InSAR) to work out exactly how the ground surface has displaced as the result of an earthquake to pinpoint both the source of the quake and its impact on related faults.  

Richard told AS: 'Compared with seismology, InSAR can identify an earthquake’s precise location. For instance, there are many faults in the L’Aquila region, and it wasn’t immediately apparent which had ruptured.'

'InSAR located the earthquake on the Paganica fault, which was less well known than other nearby faults. The data showed one side of the fault moved up a maximum of 8 centimetres while the other moved down a maximum of 25 centimetres. Using our model, we also estimated a maximum slip of 90 centimetres about 7 kilometres below the surface.'

Richard goes on to explain that the data has enabled them to show that the fault is associated with smaller, less obvious, topographic features:

'This has implications for Italy and similar regions. In addition, by modelling, we can try to understand the nature of an earthquake and its source fault. And we can calculate how an event may have moved other nearby faults closer to failure. This is important for assessing seismic hazards.'

'Several faults near L’Aquila that were moved closer to failure are near the historic towns of Amatrice and Campotosto and near a large reservoir with a hydroelectric dam.'

It just goes to show how useful having an eye in the sky can be.