Space yields insight into volcanic eruptions

Space yields insight into volcanic eruptions

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France: Scientists are using satellite imagery to predict the place where volcanic eruptions could strike. The study is likely to become an important asset for nations which are vulnerable to volcanoes. Experts hope to be able to predict the location of next large eruption, based on the effects that past eruptions had on the surrounding landscape in the same region.

The European Space Agency (ESA) is collaborating with experts in the United Kingdom, the United States, and Ethiopia, in producing viable radar data of a volcano in the African nation.

The mountain, located in the Ethiopian Afar Desert, erupted in September 2005, and this event forced underground magma upwards through a dyke, which is basically a crack in Earth’s surface.
The end result of this event was the creation of a 60-km-long tear in the Earth’s crust and appearance of 12 dykes in the same area over the next 4 years.

Scientists have been using Envisat images to observe the area since the volcanic eruption took place, checking how stress levels in the ground change over time, potentially yielding clues to future eruptions.

Magma moves below the surface of the Earth through complex underground chamber systems. As vast amounts of molten rock pass from one chamber to the other, they create visible effects on the surface. The land above the emptied chambers deflates, whereas those above chambers where magma accumulates inflate.

An observations technique known as synthetic aperture radar interferometry (InSAR) can detect these surface changes, and produce “interferogram” images of the variations. Envisat has such an instrument.

Data from the satellite seem to indicate that subsequent eruptions which rocked the desert had the same sources, experts write in the latest issue of the esteemed scientific journal Nature Geoscience.

They believe that the dykes which developed following the primary eruption did not appear at random. About 75 percent of them originated in areas that had been disturbed by the appearance of the 2005 dyke.

“This result indicates that stress changes induced by a new dyke are a controlling factor on the location of future events, so surface deformation should be routinely monitored to improve volcanic hazard warnings,” said expert Dr Ian Hamling. “Knowing the state of stress in this way won’t tell you when an eruption will happen, but it will give a better idea of where it is most likely to occur,” added the scientist, who is the lead author of the study.

“These findings are unique and will help us better predict the location of future eruptions and help authorities issue timely evacuation warnings,” added University of Leeds expert and study coauthor Dr Tim Wright. “Regular Envisat satellite passes have allowed us to build a unique dataset, without which it would not have been possible to test the idea that stress controls the location of future activity,” he concluded.

Source: ESA