Via AFP:
Bulging in land that occurs before a volcano erupts points to how much ash will be spewed into the sky, providing a useful early warning for aviation, geologists in Iceland said on Sunday.
The telltale came from data from Global Positioning System (GPS) sensors placed around the notorious Icelandic volcano Grimsvoetn, they said.
Just before Grimsvoetn blew its stack in May 2011, the ground around the volcano started to bulge.
In a brief but violent eruption, it disgorged a 20-kilometre-high (12-mile) plume of ash, equivalent to 0.27 square kilometres (0.06 cubic miles) of material.
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