Photo by Freysteinn Sigmundsson, 2004 (Nordic Volcanological Center).
Eruption dates: 2011, 2004, 1998, 1996, 1984?, 1983, 1972, 1954, 1948?, 1945, 1941?, 1939?, 1938, 1934, 1934, 1933,1922, 1902-04, 1897, 1891-91, 1887-89, 1883, 1873, 1867, 1861?, 1854, 1838, 1823, 1816, 1794?, 1783-85, 1774, 1768, 1753, 1725, 1716, 1706, 1684-85, 1681, 1659, 1638, 1629, 1619, 1603, 1598, 1500?, 1354?, 1341, 1332, 1060?, 905?
|New Activity / Unrest|
|An eruption commenced on 21st May 2011. Information links below.|
Icelandic Met Office Quake Map sequence at start of 2011 eruption. (Bottom of page)
Grimsvötn volcano (N 64.41°, W 17.33°), situated near the center of the Vatnajökull ice cap in central Iceland, is one of Iceland’s most active volcanoes. It has a complex of calderas (Gudmundsson and Milsom, 1997), and a subglacial caldera lake sustained by geothermal heat. Small eruptions have occurred at the volcano in 1983 and 1998 (around 0.1 km3). In 1996, the Gjálp subglacial eruption occurred north of the volcano (Gudmundsson et al., 1997).
This volcano is but a part of a larger system, a system that has produced the largest lava flows in recorded history and may have been responsible for as many as 2 million deaths.
You can see the Wikipedia page on Grimsvotn here but be aware the the information on the latest events may not be 100% accurate.
This is the information from the Smithsonian Institute. See an extract below:
The geothermal area in the caldera causes frequent jökulhlaups (glacier outburst floods) when melting raises the water level high enough to lift its ice dam. Long NE-SW-trending fissure systems extend from the central volcano. The most prominent of these is the noted Laki (Skaftar) fissure, which extends to the SW and produced the world’s largest known historical lava flow during an eruption in 1783. The 15-cu-km basaltic Laki lavas were erupted over a 7-month period from a 27-km-long fissure system. Extensive crop damage and livestock losses caused a severe famine that resulted in the loss of one-fifth of the population of Iceland.
Image of Grimsvotn by NASA satellite during the 2004 eruption showing the ash plume.
From a portion of the Big Think blog by Erik Klemetti – Vatnajökull and the volcanoes under the glacier in Iceland
Finally, the most famous subglacial resident at Vatnajökull is Grímsvötn – not only is it one of the most active volcanoes on Iceland, but it also erupted as recently as 2004 (see above). Much like Bardarbunga, Grímsvötn is a central edifice on a long set of SW-NE trending fissures, a set of lineaments that produced one of the most significant historic eruptions, the 1783 Laki (Skaftar Fires) fissure event. The Laki eruption produced over 15 km3 of basaltic lava over a mere 7 months over 27-km of fissures (see below). The Laki eruption did produce significant changes to weather in the northern hemisphere due to the release of volcanic aerosols like sulfur dioxide and was the source of one of the first connections between volcanoes and climate made by Benjamin Franklin (although he incorrectly attributed the eruption to Hekla) – it tends to be somewhat tenuously linked to all sorts of world events at the time. Grímsvötn has also had a number of non-fissure eruptions, producing explosive eruptions and accompanying jokulhlaups in 2004, 1996-98, 1983-84 and many more over the last few centuries. Most of these eruptions where in the VEI 1-2 scale, so fairly small, although in 1902 and 1873, the volcano produced explosive eruptions that ranked upwards of VEI 4. Grímsvötn is also known to produce jokulhlaups that are not directly related to volcanic eruption, such as the glacial outburst flood this last fall, likely caused by a breach of a subglacial lake near the volcano.