Satellite imagery identifies 'inflation' of volcanoes prior to eruption
Estelle Chaussard and Falk Amelung from the University of Miami Rosenstiel School of Marine & Atmospheric Science analysed data from Interferometric Synthetic Aperture Radar (InSAR) to investigate the deformation of volcanoes in Indonesia's west Sunda Arc -- the volcanic arc that marks the boundary between the East Eurasian tectonic plates that underlie Indonesia and produced the islands of Sumatra and Java -- prior to eruption.
The fact that the deformation could be detected by satellite presents a step forward in volcanology as remote imaging could in the future be used to help forecast eruptions in places where there might not be ground-based monitoring systems.
Chaussard said in a press release which coincided with the publication of a paper in Geophysical Research Letters: "Surveying entire volcanic regions using satellite data is of primary importance to the detection of ground deformation prior to the onset of eruptions. If volcanic inflation is observed, it can help us to predict where the next eruption may occur.
"Moreover, in regions like Indonesia, where volcanoes are prevalent and pose a threat to millions of people, and where ground-based monitoring is sparse, remote sensing via satellite could become a major forecasting tool."
The team worked by analysing more than 800 InSAR images from the Japanese Space Exploration Agency's ALOS satellite, focusing on 79 volcanoes in Indonesia between 2006 and 2009. They noticed the "inflation" at six volcanic centres, three of which later erupted. This provided confirmation that inflation is a common precursor to volcanic eruptions -- at least in the area being examined.
Amelung said that the "notion of detecting deformation" prior to an eruption has been "around for a while" but that we now have a "tool that can tell us where eruptions are more likely to occur". The team plans to extend their studies to the Philippines, using data from ALOS-2, which launches in 2013.
Amelung recognises that it's not possible to "predict activity with certainty" but that new satellite tools can "help us gather critical information in near real-time" to allow resources to be deployed "in a timely manner".
The manner in which volcanic regions deform is dependent on the region. Indonesian volcanoes, for example, have magma reservoirs at shallow depths, which tends to be associated with a higher risk for significant eruption and the associated "inflation".
Similar inflation was observed between January 2011 and April 2012 around Santorini's volcano, which has led volcanologists to question whether it is a precursor to an eruption. A paper in Nature Geoscience documented the expansion, attributing it to a series of small earthquakes in the region. Wired