by Carolyn Gramling Thursday, January 5, 2012
There's a lot of great info out there about the Iceland eruption's geology, if you know where to link.
An invaluable source of information on the geologic evolution of the eruption at Eyjafjallajokull has been the Eruptions blog at Scienceblogs. Geologist Erik Klemetti has a great post up today describing in detail how the volcanism there is now changing, including lava flows from the new crater and a smaller ash plume. He suggests that at least at the moment the volcano is displaying Strombolian activity (see below).
Klemetti also discusses the importance of water in an eruption. Water has probably played a key role here: This volcano might appear to have the wrong chemistry for an explosive eruption, but because it is subglacial, glacial meltwater — converted to steam — may be helping to produce more explosiveness. Klemetti does include a few volcano terms, most of which have to do with different eruption styles (more/less explosive, more/less water and so forth), with which you might be unfamiliar.
So here's a quick glossary:
These are mildly explosive eruptions; there are periodic lava bombs and glowing ash, but smaller ash plumes. The milder explosiveness also suggests less water in the lava — at least temporarily.
Large wet eruptions, with lots of wet ash. Here's a YouTube video of this type of eruption. This has happened a lot in Iceland over time.
These are named after a shallow Icelandic sea, because they occur in shallow seas or lakes. The shallow part is key: The combination of a lot of heat and less pressure helps transform any dissolved water into steam, which can make for a more explosive eruption.
Still want more? USGS has more on the types of volcanic eruptions, including Hawaiian, Vesuvian and so forth.
Images: NASA has satellite pics of the ash plume. Here's an animated graphic of the ash plume's spread across Europe.
And, for context, if you're wondering about the potential for eruption/damage from other volcanoes around the world ... USGS has an interesting list of "Decade Volcanoes," the 16 volcanoes around the world that might do the most damage should they erupt, based on their history of powerful eruptions and proximity to people.
Those volcanoes were identified by the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) as being particularly important to study. The criteria: The volcanoes can produce more than one volcanic hazard (e.g. ash fall, pyroclastic flows, lava, lahars, lava dome collapse); recent geological activity; proximity to a populated area; and accessibility to researchers for study.
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