Indonesian Arc

Another recent research study in Geophysical Research Letters used satellite data - namely inSAR (Interferometric Synthetic Aperture Radar) to measure how much volcanoes along the Indonesia arc are inflating or deflating. Not surprisingly in such an active arc, they found that many volcanoes were showing signs of inflation or deflation during 2006-09 -- six in total (out of 80 observed) -- and three ended up erupting during that period. Now, that seems significant, but (caution: small sample size) that is still only 50/50, so we're far from understanding how much/little inflation is needed to be sure a volcanic will erupt. However, it does show how important remote sensing can be for longterm monitoring of volcanoes in places that are difficult to monitor from the ground.

Image: Figure from Chaussard and Amelung (2012), GRL