Coordinates: 63°37′59″N 19°36′00″W / 63.633°N 19.6°W
The 2010 eruptions of Eyjafjallajökull are a timeline of volcanic events at Eyjafjöll in Iceland which, although relatively small for volcanic eruptions, caused enormous disruption to air travel across western and northern Europe over an initial period of six days in April 2010. Additional localised disruption continued into May 2010. The eruption was declared officially over in October 2010, when snow on the glacier did not melt.
Seismic activity started at the end of 2009 and gradually increased in intensity until on 20 March 2010, a small eruption started rated as a 1 on the Volcanic Explosivity Index.
Beginning on 14 April 2010, the eruption entered a second phase and created an ash cloud that led to the closure of most of Europe's IFR airspace from 15 until 20 April 2010. Consequently, a very high proportion of flights within, to, and from Europe were cancelled, creating the highest level of air travel disruption since the Second World War.
The second phase of the eruption started on 14 April 2010 and resulted in an estimated 250 million cubic metres (330,000,000 cu yd) (¼ km) of ejected tephra. The ash plume rose to a height of approximately 9 kilometres (30,000 ft), which rates the explosive power of the eruption as a 4 on the Volcanic Explosivity Index.
By 21 May 2010, the second eruption phase had subsided to the point that no further lava or ash was being produced.
By the morning of 24 May 2010, the view from the web camera installed on Þórólfsfell showed only a plume of water vapour surrounded by a blueish haze caused by the emission of sulphurous gases.
Due to the large quantities of dry volcanic ash lying on the ground, surface winds frequently lifted up an "ash mist" that significantly reduced visibility and made web camera observation of the volcano impossible.
By the evening of 6 June 2010, a small, new crater had opened up on the west side of the main crater from which explosive activity was observed with the emission of small quantities of ash. Seismic data showed that the frequency and intensity of earth tremors still exceeded the levels observed before the eruption, therefore scientists at the Icelandic Meteorological Office (IMO) and the Institute of Earth Sciences, University of Iceland (IES) continued to monitor the volcano.
In October 2010, Ármann Höskuldsson, a scientist at the University of Iceland Institute of Earth Sciences stated that the eruption is officially over, although the area is still geothermally active and might erupt again.
Background
Eyjafjallajökull (pronounced (
listen)) is one of the Iceland's smaller ice caps located in the far south of the island. It's situated to the north of Skógar and to the west of the larger ice cap Mýrdalsjökull.
The ice cap covers the caldera of a volcano 1,666 metres (5,466 ft) in height that has erupted relatively frequently since the last ice age. The most recent major eruptions occurred in 1921, 1612 (believed to have lasted only three days) and from 1821 to 1823 . Previous eruptions of Eyjafjallajökull have been followed by eruptions at its larger neighbour, Katla;. On 20 April 2010 Icelandic President Ólafur Grímsson said that, "the time for Katla to erupt is coming close ... we [Iceland] have prepared ... it is high time for European governments and airline authorities all over the world to start planning for the eventual Katla eruption".
The volcanic events starting in March 2010 are considered to be a single eruption divided into different phases. The first eruption phase ejected olivine basaltic andesite lava several hundred metres into the air in what is known as an effusive eruption. Ash ejection from this phase of the eruption is small, rising to no more than 4 kilometres (2.5 mi) into the atmosphere.
On 14 April 2010, however, the eruption entered an explosive phase and ejected fine, glass-rich ash to over 8 kilometres (5.0 mi) into the atmosphere. The second phase is estimated to be a VEI 4 eruption, which is large, but not nearly the most powerful eruption possible by volcanic standards. By way of comparison, the Mount St. Helens eruption of 1980 was rated as 5 on the VEI, and the 1991 eruption of Mount Pinatubo was rated as a 6.
What made this volcanic activity so disruptive to air travel was the combination of the following four factors:
- The volcano's location is directly under the jet stream
- The direction of the jet stream was unusually stable at the time of the eruption's second phase, maintaining a continuous south-easterly heading
- The second eruptive phase took place under 200 m (660 ft) of glacial ice. The resulting meltwater flowed back into the erupting volcano which created two specific phenomena:
- The rapidly vapourising water significantly increased the eruption's explosive power
- The erupting lava cooled very rapidly, which created a cloud of highly abrasive, glass-rich ash, this caused a large amount of flights to be cancelled in the U.K.
- The volcano's explosive power was sufficient to inject ash directly into the Jet Stream.
Without the specific combination of the above factors, the eruption of Eyjafjallajökull would have been a medium sized, somewhat non-descript eruption that would have been of little interest to those outside the scientific community or those living in the immediate vicinity. However, the above factors were precisely those required for the jet stream to carry the ash directly over northern Europe into some of the busiest airspace in the world.
Public observations
"Volcano tourism" quickly sprang up in the wake of the eruption, with local tour companies offering day trips to see the volcano. The Civil Protection Department of the Icelandic Police produced regular reports about access to the area, including a map of the Restricted Area around Eyjafjallajokull, from which the public was excluded.
Vodafone and the Icelandic telecommunications company Míla installed webcams giving views of the eruption from Valahnúkur, Hvolsvöllur and Þórólfsfell. The view of the eruption from Þórólfsfell also includes a thermal imaging camera.
Scientific observations
This eruption has been assigned the volcano number 1702-02 by the Global Volcanism Program.
The London Volcanic Ash Advisory Centre (VAAC), part of the UK Met Office, is responsible for forecasting the presence of volcanic ash in the north-east Atlantic. All ash dispersion models for this geographic region are produced by the VAAC in London.
A study by the Icelandic Meteorological Office published on December 2009 indicated an increase in seismic activity around the Eyjafjallajökull area during the years 2006–2009. The study reported increased activity that occurred between June and August 2009 (200 events), compared to a total of about 250 earthquakes recorded between September 2006 and August 2009. It further indicated that the locations of most of the earthquakes in 2009 occurred between 8 to 12 kilometres (5.0 to 7.5 mi) depth east of the volcano‘s top crater. At the end of December 2009, seismic activity began around the Eyjafjallajökull volcano area, with thousands of small earthquakes (mostly of magnitude 1–2 Mw), 7 to 10 kilometres (4.3 to 6.2 mi) beneath the volcano.
The radar stations of the Meteorological Institute of Iceland did not detect any appreciable amount of volcanic ashfall during the first 24 hours of the eruption. However, during the night of 22 March, they reported some volcanic ash fall reaching the Fljótshlíð area (20 to 25 kilometres (12 to 16 mi) north-west of the eruption's location) and Hvolsvöllur town (40 kilometres (25 mi) north-west of the eruption location) leaving vehicles with a fine grey layer of volcanic ash. At around 07:00 on 22 March, an explosion launched eruption columns as far as 4 kilometres (13,000 ft) straight up into the air. This was the highest plume since the eruption started. On 23 March, a small vapour explosion took place, when hot magma came into contact with nearby snowdrifts, emitting a huge vapour plume which reached an altitude of 7 kilometres (23,000 ft), and was detected on radars from the Meteorological Institute of Iceland. Since then many vapour explosions have taken place.
By 26 February 2010 the Global Positioning System (GPS) equipment used by the Iceland Meteorological Office at Þorvaldseyri farm in the Eyjafjöll area (around 15 kilometres (9.3 mi) southeast of the location of the recent eruption) had shown 3 centimetres of displacement of the local crust in a southward direction, of which a 1 centimetre displacement had taken place within four days. (See the GPS Time Series page of the Nordic Volcanological Center's website for detailed information on the degree of movement detected in the Earth's crust in the Eyjafjallajökull locality.)
This unusual seismic activity along with the rapid movement of the Earth's crust in the area gave geophysicists evidence that magma was flowing from underneath the crust into the magma chamber of the Eyjafjallajökull volcano and that pressure stemming from the process caused (in geophysical terms) the huge crustal displacement at Þorvaldseyri farm. The seismic activity continued to increase and from 3 to 5 March, close to 3,000 earthquakes were measured having their epicentre at the volcano. Most of these were too small (magnitude 2) to be interpreted as precursors to an eruption, but some could be detected in nearby towns.
The most recent scientific observations are on the website of the Institute of Earth Sciences which details the current situation for the eruption in Eyjafjallajökull. The Nordic Volcanological Center also maintains an Eyjafjallajökull status page.
Phase 1: Effusive eruption
The first phase of the eruption lasted from 20 March to 12 April 2010 and was characterised by alkali-olivine basalt lava flowing from various eruptive vents on the flanks of the mountain.
Evacuations
About 500 farmers and their families from the areas of Fljótshlíð, Eyjafjöll, and Landeyjar were evacuated overnight (including a group of 30 schoolchildren and their 3 teachers from Caistor Grammar School in England), and flights to and from Reykjavík and Keflavík International Airport were postponed, but on the evening of 21 March, domestic and international air traffic was allowed again. Inhabitants of the risk zone of Fljótshlíð, Eyjafjöll, and Landeyjar area were allowed to return to their farms and homes after an evening meeting with the Civil Protection Department on 22 March and the evacuation plan was temporarily dismissed. Instead, the police closed the road to Þórsmörk, and the four-wheel-drive trail from Skógar village to the Fimmvörðuháls mountain pass, but these roads and trails were reopened on 29 March, though only for suitable four-wheel drives. When the second fissure appeared, the road was closed again because of the danger of flash floods, which could have developed if the fissure had opened near big ice caps or other snow reservoirs, but the road was again opened at around noon on 1 April.
Effect on river water
On 22 March, a flow meter device situated in the Krossá glacial river (which drains Eyjafjallajökull and Mýrdalsjökull glaciers) in the Þórsmörk area (a few kilometres north-west of the erupting location) started to record a sudden rise in water level and in water temperature – the total water temperature rose by 6 °C (11 °F) over a two-hour period, which had never occurred so quickly in the Krossá river since measurements began. Shortly afterward, the water level returned to normal and water temperature decreased as well. It is thought that this rise in water temperature is related to the eruption nearby and is affecting part of the Krossá drainage basin. The temperature of Hruná river, which flows through the narrow Hrunárgil canyon, into which part of the lava stream has been flowing, was recently recorded by geologists to be between 50 °C (122 °F) and 60 °C (140 °F), indicating that the river has been cooling the lava in that canyon.
Fissure
The first phase of the 2010 eruption began late on the evening of 20 March at the Eyjafjallajökull.
The initial visual report of the eruption was at 23:52 GMT, when a red cloud was observed at the northern slopes of Fimmvörðuháls mountain pass, lighting up the sky above the eruptive site. The eruption was preceded with intense seismicity and high rates of deformation in the weeks before the eruption, in association with magma recharging of the volcano. Immediately prior to the eruption the depth of seismicity had become shallow, but was not significantly enhanced from what it had been in the previous weeks. Deformation was occurring at rates of up to a centimetre a day since 4 March at various GPS sites installed within 12 kilometres (7.5 mi) from the eruptive site.
A fissure opened up about 150 metres (490 ft) in length running in a north-east to south-west direction, with 10 to 12 erupting lava craters ejecting lava at a temperature of about 1,000 °C (1,800 °F) up to 150 metres (490 ft) into the air. The lava is alkali olivine basalt and is relatively viscous causing the motion of the lava stream to the west and east of the fissure to be slow. The molten lava has flowed more than 4,000 metres (2.5 mi) to the north-east of the fissure and into Hrunagil canyon, forming a lava fall more than 200 metres (660 ft) long and is slowly approaching Þórsmörk, but has not yet reached the flood plains of Krossá.
On 25 March 2010, while studying the eruption, scientists witnessed, for the first time in history, the formation of a pseudocrater during a steam explosion. Crustal expansion continued at Þorvaldseyri for two days after the eruption began, but has been slowly decreasing whilst the volcanic activity increased. This indicates that the rate at which magma is flowing into the magma chamber roughly equals the rate at which it is being lost due to the eruption, giving evidence that this phase of volcanic activity has reached equilibrium.
A new fissure opened on 31 March, around 200 metres (660 ft) north-west of the original fissure. Many witnesses were present while the new fissure opened. It is a bit smaller, around 300 metres (980 ft) long according to witnesses, and lava coming from it has now started to flow into Hvannárgil canyon. These two erupting fissures share the same magma chamber according to geophysicists. No unusual seismic activity was detected at the time the new fissure appeared, nor any crustal expansion according to many seismometers and GPS recorders situated in nearby areas.
Geophysicist Magnús Tumi Einarsson said (at a press meeting in Hvolsvöllur on 21 March) that this eruption is small compared to, for example, the eruption of Hekla in 2000. The eruption, rather than taking place under the ice cap of the glacier, occurred in the mountain pass between the Eyjafjallajökull and Mýrdalsjökull glaciers. As long as the fissure is not near the glacier, the risk of flooding is minimal; however, the fissure could extend into the ice cap thereby greatly increasing the risk of flooding.
Phase 2: Explosive eruption
After a short hiatus in eruptive activity a new set of craters opened early in the morning of 14 April 2010 under the volcano's ice covered central summit caldera. Prior to this event, a large increase in seismic activity was detected between 23:00 on 13 April and 1:00 on 14 April. The earthquake swarm was followed by the onset of a seismic eruption tremor. Meltwater started to emanate from the ice cap around 07:00 on 14 April and an eruption plume was observed in the early morning. Visual observations were greatly restricted due to cloud cover over the volcano, but an airplane of the Icelandic Coast Guard imaged with eruptive craters with radar instruments. A series of vents along a 2-kilometre (1.2 mi) long north-south oriented fissure were active, with meltwater flowing mostly down the northern slopes of the volcano, but also to the south. An ash loaded eruption plume rose to more than 8 kilometres (5.0 mi), deflected to the east by westerly winds.
Ash analysis
Samples of volcanic ash collected near the eruption showed a silica concentration of 58%—much higher than in the lava flows. The concentration of water-soluble fluoride is one third of the concentration typical in Hekla eruptions, with a mean value of 104 milligrams of fluoride per kilogram of ash. Agriculture is important in this region of Iceland, and farmers near the volcano have been warned not to let their livestock drink from contaminated streams and water sources, as high concentrations of fluoride can have deadly renal and hepatic effects, particularly in sheep.
Impact on farming
The Icelandic Food and Veterinary Authority released an announcement on 18 April 2010, asking that all horse owners who keep their herds outside be on the alert for ash fall. Where there is significant ash fall all horses must be sheltered indoors. The thick layer of ash that has fallen on some Icelandic farms and pastures at Raufarfell has become wet and compact, making it very difficult to continue farming, harvesting or grazing livestock.
Timeline of the second eruption phase
Unlike the earlier eruption phase, the second phase occurred beneath glacial ice. Cold water from melted ice quickly chilled the lava causing it to fragment into highly abrasive glass particles that were then carried into the eruption plume. This, together with the magnitude of the eruption (estimated to be VEI 4) and being ten to twenty times larger than the eruption of Fimmvörðuháls on 20 March, injected a glass-rich ash plume into the Jet Stream.
In addition to the fact that volcanic ash is very hazardous to aircraft, the location of this eruption directly under the Jet Stream ensured that the ash was carried into the heavily used airspace over northern and central Europe.
Phase 3: Return to dormancy
Since 21 May 2010, the eruptive vent has been emitting a column of steam (water vapour) plus sulphurous gases. Therefore there has been no further report of any ash fall from the surrounding area.
Data from seismic recorders in the area indicates that the frequency and strength of earth tremors has diminished, but is continuing.
Due to the volcano's currently quiet state, scientists from the Icelandic Meteorological Office (IMO) and the IES will no longer produce status reports on a daily basis, but rather every few days; however, the volcano remains under close scientific observation.
As of 23 June 2010, the activity of Eyjafjallajökull has reduced to occasional, brief bursts of ash that travel no more than a few tens of metres.
In October 2010, Ármann Höskuldsson, a scientist at the University of Iceland Institute of Earth Sciences, stated that the eruption is officially over, although the area is still geothermally active and might erupt again. Steam still rises from the lava flows.
Volume of erupted material and magma discharge
The Institute of Earth Sciences made a preliminary estimate of erupted material in the first three days of the eruption on 14 April 2010 at Eyjafjallajökull. The erupted products are fragmented material, the majority fine-grained airborne tephra. Eruptive products can be split into three categories along with preliminary estimated erupted volumes:
- Material (tephra) in the ice cauldrons around the volcanic vents: 30 million cubic metres (39,000,000 cu yd)
- Tephra filling the glacial lagoon of Gígjökulslón, carried by floods down the outlet glacier Gígjökull: 10 million cubic metres (13,000,000 cu yd)
- Airborne tephra that has been carried to the east and south of the volcano. Uncompacted tephra fallout from eruption plume: 100 million cubic metres (130,000,000 cu yd)
Total: 140 million cubic metres (180,000,000 cu yd) which corresponds to some 70–80 million cubic metres (92,000,000–100,000,000 cu yd) of magma. The magma discharge rate is about 300 cubic metres per second (11,000 cu ft/s) or 750 t/s. This is 10–20 times the average discharge rate in the preceding flank eruption at Fimmvörðuháls.(First Eruption on 20 March 2010).
The IES updated the eruption flow rate on 21 April 2010 to estimation of less than 30 cubic metres per second (1,100 cu ft/s) of magma, or 75 tonnes/s, with a large uncertainty. IES also noted that the eruption continue with less explosive activity.
Effects of the ash plume on air travel
Volcanic ash is a major hazard to aircraft. Smoke and ash from eruptions reduce visibility for visual navigation, and microscopic debris in the ash can sandblast windscreens and melt in the heat of aircraft turbine engines, damaging engines and making them shut down. Many flights within, to, and from Europe were cancelled following the 14 April 2010 eruption, and although no commercial aircraft were damaged, the engines of some military aircraft were harmed. The presence and location of the plume depends upon the state of the eruption and the winds. While some ash fell on uninhabited areas in Iceland, most had been carried by westerly winds resulting in the shut down of a large air space over Europe. The shut down had a knock on impact on the economy and cultural events across Europe.
Short- and long-term weather and environmental effects
At the mouth of the crater, the gases, ejecta, and volcanic plume have created a rare weather phenomenon known as volcanic lightning (or a "dirty thunderstorm"). When rocks and other ejecta collide with one another, they create static electricity. This, coupled with the abundant amount of water-ice located at the summit, aids in the creation of lightning.
High-fluoride Hekla eruptions pose a threat to foraging livestock, especially sheep. Fluoride poisoning can start in sheep at a diet with fluorine content of 25 ppm. At 250 ppm, death can occur within a few days. In 1783, 79 percent of the Icelandic sheep stock were killed, probably as a result of fluorosis caused by the eruption of Laki. The effect also spread beyond Iceland. Ash from the current Eyjafjallajökull eruption contains one third the concentration typical in Hekla eruptions, with a mean value of 104 milligrams of fluoride per kilogram of ash. Large-scale release of sulphur dioxide into the troposphere also poses a potential health risk, especially to people with pre-existing breathing disorders.
While it is suspected that major volcanic eruptions that coincide with cyclic solar minimum activity could produce temporary global cooling or reduction in global temperature, it is noted that coincidentally the earth-facing side of the Sun was mostly blank with no sun spots since the start of the second eruption phase on 14 until 29 April 2010. Although the current unusually long solar minimum came to a close earlier this year, the current cycle may witness unusual weak solar maximum. Other research links volcanic eruptions including recent Icelandic activity to the solar cycle. Most consider the climate anomaly of the Year Without A Summer 1816 to have been caused by a combination of a historic low in solar activity with a volcanic winter event; the latter caused by a succession of major volcanic eruptions capped off by the Mount Tambora eruption of 1815, the largest known eruption in over 1,600 years. One proposed volcanic winter happened c. 70,000 years ago following the supereruption of Lake Toba on Sumatra island in Indonesia.
As of 15 April, the eruption was not large enough to have an effect on global temperatures like that of Mount Pinatubo and other major past volcanic eruptions. One previous related sequence of eruptions of this volcano, beginning in 1821 is recorded as having lasted for over two years, however no single set of major eruptions is known to have lasted more than 'several days'. Should the eruption continue for a sufficient length of time at its current intensity, the potential remains for a temporary global cooling effect. By analogy, the Laki eruption has been linked with extreme weather events from severe hailstorms in Great Britain to the Mississippi River freezing at New Orleans. Sulfate aerosols that reach the stratosphere catalyze the production of chlorine monoxide (ClO), which destroys ozone (O3). In the upper troposphere, the same aerosols become nuclei for cirrus clouds, which increase the Earth's albedo and thus alter its radiation balance. Several eruptions during the past century have caused a decline in the average temperature at the Earth's surface of up to half a degree Celsius for periods of one to three years.
The eruption may have affected atmospheric carbon dioxide levels by fertilizing oceans with iron. According to the Nordic Volcanological Center at the University of Iceland ash samples contained 8 to 12% iron oxide. Observations at the Mauna Loa Observatory show increased carbon dioxide absorption for each of the three months following the eruption compared to the 30 year mean for the same months. Over May, June and July 2010 atmospheric carbon dioxide decreased by a total of 2.40 ppm. The thirty year mean for the same months is 1.66 ppm with a standard deviation of 0.52ppm. The probability of a chance result is less than 8%.
Comparison to other recent eruptions
The recent eruptions of Eyjafjallajökull and the largest ash plume associated with the second eruption phase were not unparalleled in either volume or abundance; however, the location was the critical factor because it affected air travel across Europe. Neither phase of the eruption was unusually powerful. Other notable volcanic eruptions in recent years include the eruption of Mount Pinatubo of 1991 of VEI 6. This eruption lasted 8 days, from 7 – 15 June of that year, with an ash cloud that would have required additional days to dissipate, and resulted in worldwide abnormal weather and decrease in global temperature over the next few years. However, the second phase of Eyjafjallajökull's eruption lasted longer than that of Mount Pinatubo.
According to the SI / USGS Weekly Volcanic Activity Report (14–20 April 2010) by the Smithsonian's Global Volcanism Program, the second eruption phase at Eyjafjallajökull coincided with eruptions at a number of other volcanoes, including new activity at:
- Barren Island, Andaman, India plume rose to an altitude of 2.4 kilometres (7,900 ft) and drifting 55 kilometres (34 mi) to the north on 19 April 2010.
- Gaua, Banks Islands, SW Pacific, Vanuatu ash plumes reported from during 13–16 and 19–21 April 2010. The plumes regularly rose to altitudes of 3 kilometres (9,800 ft). A spokesman for the Vanuatu Disaster Management Office described the activity as "huge, dark plumes" in an AAP news report.
Public media
See also
References
External links
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Coordinates: 63°37′59″N 19°36′00″W / 63.633°N 19.6°W
Retrieved from :
http://en.wikipedia.org/wiki/2010_eruptions_of_Eyjafjallaj%C3%B6kull
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