General information

The Grímsvötn (Icelandic vatn, or "lake") are lakes in Iceland. They lie in the highlands of Iceland at the northwestern side of the Vatnajökull glacier and are covered by its ice cap. Under them, there is the big magma chamber of a powerful volcano. The location of the lakes is 64° 25′ N, 17° 20′ W, at an elevation of 1725 m (5659 ft).

Jökulhlaup

Eruptions under the icecap regularly give rise to glacial bursts, known in Icelandic as jökulhlaups. Eruptions may melt enough ice to fill the Grímsvötn caldera with water, and the pressure may be enough to suddenly lift the icecap, allowing huge quantities of water to escape rapidly. As a result, the Grímsvötn caldera is monitored very carefully by scientists. When a large eruption occurred in 1996, geologists knew well in advance that a glacial burst was imminent. It didn't occur until several weeks after the eruption finished, but the monitoring allowed the closing of the Icelandic ring road (Hringvegur) when the burst occurred. A section of road across the Skeiðará sandur was washed away in the ensuing flood, but no-one was hurt.

Last eruptions

A week-long eruption occurred at Grímsvötn starting on 28 December 1998, but no glacial burst occurred. In November 2004 another eruption of about one week began. Ash from the eruption was falling as far away as mainland Europe, and causing short-time disruption to airline traffic into Iceland. But no glacier run followed the eruption.

Bacteria in the lakes

An interesting discovery was made in summer 2004 by scientists concerning the Grímsvötn:

For the first time, they found bacteria in the water of lakes under a glacier. The lakes don’t freeze totally because of the volcanic heat which perhaps made thrive the bacteria. These are also able to survive on a very low quantity of oxygen.

The scientists see a connection to the planet Mars, because there are also traces of volcanism and glaciers to be found. So this could be one of the missing links to the existence of life on Mars.

From: [1] (http://www.nature.com/news/2004/040712/pf/040712-6_pf.html)

See also

• Lakes of Iceland'

External links

• Volcanism at Grimsvötn lakes (http://volcano.und.edu/vwdocs/volc_images/img_grimsvotn.html)
• Formation and emptying of glacier lakes (http://www.lancs.ac.uk/ug/lloydca/formation.html)
• BBC news report of the November 2004 eruption (http://news.bbc.co.uk/1/hi/sci/tech/3982273.stm)
• Independent news report of the 2004 eruption (http://www.iol.co.za/index.php?set_id=14&click_id=420&art_id=qw1099460701116T614)