Grimsvotn Volcano - John Seach

john

Iceland

64.42 N, 17.33 W
summit elevation 1725 m
caldera

Grimsvötn volcano is located under Vatnajökull ice cap in central Iceland. Two major volcanic centers lie beneath the ice, the Bardarbunga volcanic centre and the Grimsvötn volcanic centre. Grimsvötn centre is the more active of the two. 

About every 5-10 years glacial melting causes large floods (jökulhlaup) on the sandur plain. Eruptions at Grimsvotn Volcano are phreatomagmatic.

2012 Glacial Ourburst
A glacial outburst occurred at Grimsvotn volcano in Iceland on 29th January 2012. High snowfall was followed by heavy rain and elevated temperatures. This caused caused snow to melt, damaging parts of the Ring Road between Núpsvötn and Gígjukvísl in Skeiđarársandur, as well as to the east of Gígjukvísl. No eruption occurred at the volcano.

2011 Subglacial Eruption
An eruption began at Grímsvötn volcano in Iceland at approximately 17:30 UTC, on 21st May 2011. The volcano is located under the Vatnajokull glacier in south-east Iceland. The subglacial eruption sent a plume 50,000 ft high, which makes it the largest eruption in Iceland since Hekla in 1947. A 120 nautical mile flight restriction has been placed around the volcano. A group of people stayed in a hut in Grímsvötn volcano the night before the eruption, and had left an midday on Saturday six hours before the eruption started. The group noticed nothing unusual, but another group that climbed Hrútafellstindar in the southern part of Vatnajökull glacier said they smelled suphur on the morning of 21st May. More than one hundred people climbed Örćfajökull, Iceland’s highest peak on Saturday and saw nothing unusual. A flood in Skeidarársandur is expected, and will depend on the exact location of the eruption.

2010 Flood
A possible eruption occurred at Grimsvotn volcano, Iceland in October 2010. A flood started in Gigja in south-east Iceland. The disturbance occurred under the Vatnajokull glacier near Grimsvotn Volcano on 31st October 2010. There was an increase in flow of water by 30 cm but other rivers running from the glacier are dry. The flood may take 4-5 days to reach maximum. On Sunday the volume of water in Gigja was 130 cubic metres per second, and electrolyte levels double that of normal.

2004 Subglacial Eruption
A 5-day long eruption began at Grimsvotn Volcano on 1st November 2004. An intense swarm of volcanic earthquakes began 3 hours before the eruption. The eruption began under 150-200 m of ice and melted its way to the surface in 1 hour. On 2-3 November an eruption plume reached an altitude of 13 km, accompanied by volcanic lightning. The ash plume reached Norway, Finland, and Sweden. The jökulhlaup reached a maximum on the afternoon of 2nd November. The maximum discharge from affected rivers on the coastal plain at Skeidararsandur was 3,000-4,000 cubic metres per second (based on information from the Icelandic Hydrological Service). Discharge declined quickly after the peak. No damage occurred to roads or bridges. The total volume of the jökulhlaup was 0.5 cubic km.

1998 Eruption
A 10-day eruption began on 18th December 1998 within the caldera of Grímsvötn volcano, at a location 10 km S of the 1996 eruption. Within 10 minutes a plume rose 10 km above the Vatnajökull glacier. The plume was visible from Reykjavik, 200 km W. Eruption vents were located along a 1.3 km long fissure orientated E-W on the S caldera fault.

1996 Eruption
A 2-week long subglacial eruption began on 30th September 1996, along part of the East Rift Zone that traverses beneath the NW side of Vatnajökull, Europe's largest continental glacier. The eruption was preceded by earthquakes on 29th September at Bardarbunga volcano. The high-frequency tremor resulted from lateral magma
injection from a shallow magma chamber beneath Bardarbunga toward the 1996 eruption site at Gjalp.

Within a day, the earthquake hypocenters migrated 20 km south, where a subglacial eruption started during the evening of 30th September. The eruption caused glacial ice to subside by 50 m in 4 hours, forming a bowl-like depression. On 2nd October the eruption broke through the ice, creating an ash plume 500 m high. By 3rd October the glacier had subsided over an area 8-9 km long and 2-3 km wide. On 4th October, water in the caldera lake reached this highest levels of the 20th century. The eruption occurred within 70 km of the great Laki fissure eruption of 1783-85.

1983 Eruption
An eruption began at Grimsvotn Volcano on 28 or 29 May 1983. The eruption broke through ice on 29th May and deposited a 5-km long thin layer of ash on the ice cap, south of the vent. Explosions occurred in the lake, and a steam plume rose to a height of 8000 m.

1982 Eruption
On 28th January 1982 a glacier burst (jökulhlaup) occurred at Grímsvötn caldera in Vatnajökull glacier. The eruption volume was 1.3 cubic km and lowered the ice level in the caldera by 50 m.

1972 Eruption
A glacial outburst flood occurred at Grimsvotn Volcano in March 1972.

Laki (Skaftar Fires) and Grimsvotn eruptions 1783-1785
The eruption at Laki began on 8th June 1783 with a brief explosive event on a short fissure, and lava rapidly began to flow into the Skaftfi river gorge. Lava reached the lowlands, 35 km away, four days later.

Laki eruption created a 25 km long fracture and basalt lava flows extended 70 km.  The lava flow covered 565 square km (14.7 cubic km). Large amounts of gas were produced in the eruption which covered most of Europe in a blue haze.

Fluorine was released by the eruption and cattle died from eating the contaminated grass. Over 200 000 livestock were killed in Iceland and the resulting famine resulted in 10 000 deaths.

Grimsvötn Volcano Eruptions

2011, 2010?, 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?