Iceland's Katla volcano is getting restless.

[Lint Head]

VIK, Iceland (AP) – If Iceland's air-traffic paralyzing volcanic eruption last year seemed catastrophic, just wait for the sequel. That's what some experts are saying as they nervously watch rumblings beneath a much more powerful Icelandic volcano — Katla — which could spew an ash cloud dwarfing the 2010 eruption that cost airlines $2 billion and drove home how vulnerable modern society is to the whims of nature.
Brooding over rugged moss-covered hills on Iceland's southern edge, Katla is a much bigger beast than the nearby Eyjafjallajokul volcano, which chugged ash all over Europe for several weeks in an eruption that local scientist Pall Einarsson describes nonetheless as "small."

Named after an evil troll, Katla has a larger magma chamber than Eyjafjallajokul's. Its last major eruption in 1918 continued more than a month, turning day into night, starving crops of sunlight and killing off some livestock. The eruption melted some of the ice-sheet covering Katla, flooding surrounding farmlands with a torrent of water that some accounts have said measured as wide as the Amazon.
http://www.usatoday.com/news/world/story/2011-10-13/iceland-katla-volcano/50750556/1