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Eldgjá (, "fire canyon") is a
volcano A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most oft ...
and a
canyon A canyon (; archaic British English spelling: ''cañon''), gorge or chasm, is a deep cleft between escarpments or cliffs resulting from weathering and the erosive activity of a river over geologic time scales. Rivers have a natural tendency t ...
in
Iceland Iceland is a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the regi ...
. Eldgjá is part of the Katla volcano; it is a segment of a long chain of volcanic craters and
fissure vent A fissure vent, also known as a volcanic fissure, eruption fissure or simply a fissure, is a linear volcanic vent through which lava erupts, usually without any explosive activity. The vent is often a few metres wide and may be many kilo ...
s that extends northeast away from Katla volcano almost to the Vatnajökull
ice cap In glaciology, an ice cap is a mass of ice that covers less than of land area (usually covering a highland area). Larger ice masses covering more than are termed ice sheets. Description By definition, ice caps are not constrained by topogra ...
. This fissure experienced a major eruption around 939 CE, which was the largest
effusive eruption An effusive eruption is a type of volcanic eruption in which lava steadily flows out of a volcano onto the ground. Overview There are two major groupings of eruptions: effusive and explosive. Effusive eruption differs from explosive eruption ...
in recent history. It covered about of land with of lava from two major lava flows. While Icelandic records about the effects of the eruption are sparse,
paleoclimate Paleoclimatology ( British spelling, palaeoclimatology) is the scientific study of climates predating the invention of meteorological instruments, when no direct measurement data were available. As instrumental records only span a tiny part of ...
proxies and historical records from China, Europe and the
Islamic world The terms Islamic world and Muslim world commonly refer to the Islamic community, which is also known as the Ummah. This consists of all those who adhere to the religious beliefs, politics, and laws of Islam or to societies in which Islam is ...
describe widespread impacts on the Northern Hemisphere’s climate. The Eldgjá eruption produced a noticeable cooling of the climate, with resulting cold winters and food crises across Eurasia.


Geology

The interaction between the
Mid-Atlantic Ridge The Mid-Atlantic Ridge is a mid-ocean ridge (a Divergent boundary, divergent or constructive Plate tectonics, plate boundary) located along the floor of the Atlantic Ocean, and part of the List of longest mountain chains on Earth, longest mountai ...
and the Iceland hotspot has given rise to the stack of volcanic rocks that forms
Iceland Iceland is a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the regi ...
. Volcanoes on Iceland occur in four volcanic zones; the North Volcanic Zone in northeastern Iceland, the East Volcanic Zone in the southeast, the West Volcanic Zone in the southwest and the Snæfellsnes Volcanic Zone in the west. The first three of these form an upside-down Y structure, with each volcanic zone consisting of volcanic and tectonic lineaments that extend from north-northeast to south-southwest. These lineaments are dotted with volcanic edifices; Eldgjá lies in the East Volcanic Zone where there are no large
shield volcano A shield volcano is a type of volcano named for its low profile, resembling a shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more viscous lava ...
es but numerous long fissures, including
Laki Laki () or Lakagígar (, ''Craters of Laki'') is a volcanic fissure in the western part of Vatnajökull National Park, Iceland, not far from the volcanic fissure of Eldgjá and the small village of Kirkjubæjarklaustur. The fissure is proper ...
.
Glaciation A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate be ...
has influenced volcanic activity on Iceland, and the occurrence of large eruptions—such as the Þjórsá Lava 8,600 years ago—in the early
Holocene The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...
has been attributed to the unloading of the crust caused by the melting of
Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
ice. This process does not appear to have influenced the Eldgjá eruption. Eldgjá's eruption may have altered the shape of the Katla volcano and thus modified the behaviour of its glaciers. Glacial meltwater drains from Katla through several subglacial "tunnels", one of which coincides with the Eldgjá lineament, and geothermal activity on the lineament drives melting and the formation of cauldron-shaped depressions in the northeastern sector of the Myrdalsjökull Ice Cap.
Moraine A moraine is any accumulation of unconsolidated debris (regolith and Rock (geology), rock), sometimes referred to as glacial till, that occurs in both currently and formerly glaciated regions, and that has been previously carried along by a gla ...
s from the ice cap extend to the Eldgjá lineament. The rocks erupted by Eldgjá are mainly alkali basalts, which have a uniform composition and contain
phenocryst image:montblanc granite phenocrysts.JPG, 300px, Granites often have large feldspar, feldspathic phenocrysts. This granite, from the Switzerland, Swiss side of the Mont Blanc massif, has large white phenocrysts of plagioclase (that have trapezoid sh ...
s of clinopyroxene,
olivine The mineral olivine () is a magnesium iron Silicate minerals, silicate with the chemical formula . It is a type of Nesosilicates, nesosilicate or orthosilicate. The primary component of the Earth's upper mantle (Earth), upper mantle, it is a com ...
,
magnetite Magnetite is a mineral and one of the main iron ores, with the chemical formula . It is one of the iron oxide, oxides of iron, and is ferrimagnetism, ferrimagnetic; it is attracted to a magnet and can be magnetization, magnetized to become a ...
and
plagioclase Plagioclase ( ) is a series of Silicate minerals#Tectosilicates, tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continu ...
. There are also a small amount of tholeiitic rocks. The composition of Katla magmas shows evidence of long-term variations that appear to reflect a long-term cycle of its magmatic system. The Eldgjá eruption appears to be the beginning of one such cycle that continues to the present-day. There is evidence that eruptions of Eyjafjallajökull often precede eruptions at Katla, raising concerns after the 2010 eruption of Eyjafjallajökull that Katla may erupt again.


Geography and geomorphology

means "fire gorge" and is a reference to the fissure that makes up the volcano; the term is also used with other Icelandic volcanoes. It is situated between
Landmannalaugar Landmannalaugar () is a location in Iceland's Fjallabak Nature Reserve in the Highlands. It is on the edge of the Laugahraun lava field. This lava field was formed by an eruption in approximately 1477. It is largely known for its natural ...
and Kirkjubæjarklaustur. The Ófærufoss
waterfall A waterfall is any point in a river or stream where water flows over a vertical drop or a series of steep drops. Waterfalls also occur where meltwater drops over the edge of a tabular iceberg or ice shelf. Waterfalls can be formed in seve ...
, a tourist attraction, lies in the main Eldgjá fissure. There used to be an oft-photographed natural bridge at Ófærufoss, which collapsed during the early 1990s. The northern part of Eldgjá, including Ófærufoss, and surrounding areas, have been a part of Vatnajökull National Park since 2011; the entire Eldgjá is since 2010 part of the Katla Geopark. There are information centres and picnic places at Eldgjá. It consists of a northeast-southwest trending
graben In geology, a graben () is a depression (geology), depressed block of the Crust (geology), crust of a planet or moon, bordered by parallel normal faults. Etymology ''Graben'' is a loan word from German language, German, meaning 'ditch' or 't ...
with explosion craters, about long. It is wide, deep and part of a larger long chain of offset grabens. The canyon is subdivided into four segments from southwest to northeast. The northeasternmost segment is known as ); the name Eldgjá is usually only applied to the long segment in the middle of the chain, but the 939 eruption also involved other segments. The canyon extends between the Öldufellsjökull glacier of the Myrdalsjökull Ice Cap (the ice cap covers part of the fissure) in the southwest, stretches across mountainous terrain and almost reaches the Vatnajökull Ice Cap to the northeast at Stakafell mountain. It is the longest volcanic fissure in Iceland. Ground fractures, hornitos,
normal fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...
s, lava lakes, pyroclastic cones and spatter ramparts make up the Eldgjá lineament; the cones form alignments and have red-to-gray colours and consist of alternating layers of lava,
scoria Scoria or cinder is a pyroclastic, highly vesicular, dark-colored volcanic rock formed by ejection from a volcano as a molten blob and cooled in the air to form discrete grains called clasts.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackso ...
and spatter, with the scoria and spatter sometimes fused together until they resemble lava flows. There is evidence that the Eldgjá fissure existed before the 930s eruption. Ongoing activity of the fissure can be seen in the form of ground deformation. The Eldgjá is part of the wider Katla volcano, which features a series of fissures, as well as a
caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...
covered by the Myrdalsjökull Ice Cap. To the northeast, the lineament runs away from and parallel to that of the 1783-1784 CE Laki eruption fissure, which is part of the Grimsvötn volcano. There are other volcanic centres in the area, some of which had large fissure-fed eruptions within historical memory.


10th century eruption

The Eldgjá eruption was the largest Holocene eruption of the Katla system, the largest
effusive eruption An effusive eruption is a type of volcanic eruption in which lava steadily flows out of a volcano onto the ground. Overview There are two major groupings of eruptions: effusive and explosive. Effusive eruption differs from explosive eruption ...
on Earth during the last few millennia, and the only historical eruption of this volcano outside of its caldera. It involved a long area of the volcano, including both the central caldera and the Eldgjá lineament. During the course of the eruption, about 16 episodes of Plinian or subplinian eruptions took place, producing plumes with heights of . These episodes did not occur simultaneously across the entire length of the Eldgjá; rather the eruption commenced in the caldera and propagated northeastward. Intense lava fountaining,
explosive eruption In volcanology, an explosive eruption is a volcanic eruption of the most violent type. A notable example is the 1980 eruption of Mount St. Helens. Such eruptions result when sufficient gas has dissolved under pressure within a Viscosity, viscous ...
s and the effusion of lava took place. The eruption has been linked to an episode of active
continental rifting In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben ...
in the 930s, during which the injection of magma into dykes led to deformation of the ground surface and the evacuation of magmas from the Katla magmatic system. Part of this magma entered into the Katla
magma chamber A magma chamber is a large pool of liquid rock beneath the surface of the Earth. The molten rock, or magma, in such a chamber is less dense than the surrounding country rock, which produces buoyant forces on the magma that tend to drive it u ...
, triggering the release of silicic magmas that form part of the tephra and were at least for some time erupted simultaneously with basaltic magmas. Other volcanoes in Iceland such as Bárðarbunga, Grimsvötn and Reykjanes peninsula erupted at the same time as Eldgjá.


Dating

The Eldgjá eruption took place in the 930s, but its exact date had long been uncertain. Early research put its beginning during 934-938. Later research published in 2015 indicated that it began in 939 and likely ended in 940, but may have continued for several years more. Further confusion had been created because the Eldgjá eruption occurred only seven years before the Millennium Eruption of Paektu Mountain on the China–Korea border. Some climatic effects attributed to the Eldgjá eruption may actually have resulted from the Paektu eruption. That eruption, in 946 CE, may have produced only a small amount of sulfate aerosols, far less than Eldgjá. A tephra layer at Katla originally attributed to a 1000 CE eruption is now considered to be part of the Eldgjá eruption.


Products

The eruption produced two fields of (mostly pahoehoe)
lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...
s emanating from the southern and central sectors of the Eldgjá fracture. Flowing through
lava tube A lava tube, more rarely called a pyroduct, is a 'roofed conduit through which molten lava travels away from its vent'. If lava in the tube drains out, it will leave an empty cave. Lava tubes are common in low-viscosity volcanic systems. La ...
s, the lava flows were channelled down river valleys and gorges and eventually reached the sea. They cover an area of and with a volume of constitute the largest lava flows of the last 1,100 years. The lavas buried traces of earlier eruptions and obstructed river valleys, forcing the rivers to change their course, and altered the terrain so that large parts of the plains east of Katla can no longer be reached by jökulhlaups (glacier meltwater flood) from the volcano. Rootless cones such as and Iceland's largest complex at are linked to lava flows attributed to Eldgjá, although an older date for the latter lavas is possible. Later eruptions from Laki have buried many of the northeastern Eldgjá lava flows. About dense rock equivalent of mostly
basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...
ic ejecta became of
tephra Tephra is fragmental material produced by a Volcano, volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, ...
, which was emplaced mainly south and southeast from Eldgjá. The tephra was formed through alternating magmatic and phreatomagmatic processes, and is more complex than common Katla tephras. External water (such as from ice melt) did not play a major role in driving the explosivity of the eruption. Part of the eruption occurred underneath the Katla ice cap; this part also gave rise to the Kriki
hyaloclastite Hyaloclastite is a volcanoclastic accumulation or breccia consisting of glass (from the Greek ''hyalus'') fragments (clasts) formed by quench fragmentation of lava flow surfaces during submarine or subglacial extrusion. It occurs as thin marg ...
on the eastern side of the ice cap, a product of an interaction between lava and ice. The Eldgjá eruption was accompanied by jökulhlaups from the northern, eastern and perhaps also southern part of Myrdalsjökull Ice Cap but the burial of its deposits by later glacier meltwater floods and lavas make it difficult to trace the precise extent of the flood. There is evidence that the inner structure of Katla was permanently altered by the Eldgjá eruption, as eruption rate decreased compared to the rate in the previous two millennia and there have been no meltwater floods on the southern or western side of the volcano since the event.


Tephra and aerosol emissions

Both tephra layers and
sulfate The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...
layers linked to the Eldgjá eruption occur in
Greenland Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenlan ...
, where they have been recorded from
ice core An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier ...
s in the form of layers where the ice contains more
acid An acid is a molecule or ion capable of either donating a proton (i.e. Hydron, hydrogen cation, H+), known as a Brønsted–Lowry acid–base theory, Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis ...
s, salts and tiny glass shards. Tephra layers from the eruption have been used to date lake sediments and ice cores in the
Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...
, volcanic eruptions at
Eyjafjallajökull Eyjafjallajökull (; "glacier of (the mountain) Eyjafjöll"), sometimes referred to by the numeronym E15, is one of the smaller ice caps of Iceland, north of Skógar and west of Mýrdalsjökull. The ice cap covers the caldera of a volcano wi ...
and other Icelandic volcanoes,
glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...
advances on the island, and events in
Viking Age The Viking Age (about ) was the period during the Middle Ages when Norsemen known as Vikings undertook large-scale raiding, colonising, conquest, and trading throughout Europe and reached North America. The Viking Age applies not only to their ...
Iceland. Large volcanic eruptions can produce veils of
aerosol An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be generated from natural or Human impact on the environment, human causes. The term ''aerosol'' co ...
s in the atmosphere from
sulfur dioxide Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is r ...
, which reduce the amount of sunlight reaching Earth's surface and alter its climate. Eldgjá produced about of sulfur dioxide, more than that of other well-known historical eruptions (such as Tambora in 1815 and Huaynaputina in 1600) but possibly less than Laki in 1783, as phreatomagmatic activity would have scavenged sulfate from the eruption column. The Eldgjá eruption is the largest volcanic atmospheric pollution event of the last several millennia and traces of
platinum Platinum is a chemical element; it has Symbol (chemistry), symbol Pt and atomic number 78. It is a density, dense, malleable, ductility, ductile, highly unreactive, precious metal, precious, silverish-white transition metal. Its name origina ...
erupted by the volcano have been found across the
Western Hemisphere The Western Hemisphere is the half of the planet Earth that lies west of the Prime Meridian (which crosses Greenwich, London, United Kingdom) and east of the 180th meridian.- The other half is called the Eastern Hemisphere. Geopolitically, ...
, where they have been used to date
archaeological site An archaeological site is a place (or group of physical sites) in which evidence of past activity is preserved (either prehistoric or recorded history, historic or contemporary), and which has been, or may be, investigated using the discipline ...
s. The climate impact of the Eldgjá has been recorded in cave deposits, historical reports, ice cores, tree rings and other environmental records potentially as far south as
Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
. Tree rings suggest a cooling of about in the Northern Hemisphere during 940 CE, most pronounced in Alaska, the Canadian
Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in great-circle distance, straight-line distance from the northernmost part of Western Can ...
, Central Asia, Central Europe and Scandinavia; in Canada and Central Asia it lasted until 941 CE. Volcanic aerosols often weaken the
monsoon A monsoon () is traditionally a seasonal reversing wind accompanied by corresponding changes in precipitation but is now used to describe seasonal changes in Atmosphere of Earth, atmospheric circulation and precipitation associated with annu ...
s that feed the
Nile River The Nile (also known as the Nile River or River Nile) is a major north-flowing river in northeastern Africa. It flows into the Mediterranean Sea. The Nile is the longest river in Africa. It has historically been considered the longest river i ...
in Africa; during 939 the water levels of the river were unusually low. Conversely, increased flooding in Europe after the Eldgjá and other volcanic eruptions during the 10th century have been correlated to declines in
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...
's ''
Alnus Alders are trees of the genus ''Alnus'' in the birch family Betulaceae. The genus includes about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few species ext ...
'' trees. Some climate impacts attributed to Eldgjá might have been caused by simultaneous eruptions of other volcanoes, such as Ceboruco in Mexico.


Human impacts

Even though Iceland was already settled at that time and the impacts of the eruption were severe, there are no contemporary historical records of the eruption. Anecdotal reports are recorded in the Book of Settlements, which was written about 200 years later. Events in the poem
Völuspá ''Völuspá'' (also ''Vǫluspá'', ''Vǫlospá'', or ''Vǫluspǫ́''; Old Norse: 'Prophecy of the völva, a seeress') is the best known poem of the ''Poetic Edda''. It dates back to the tenth century and tells the story from Norse Mythology of ...
may record the eruption or another eruption of Katla. According to the Book of Settlements, lava flows forced settlers east of Katla off their land; two settlements or farms belonging to at least two settlements in the Álftaver area southeast of Katla had to be abandoned due to damage from lava flows and sources of the 12th century define it a "wasteland". Tephra covered an area of about on Iceland; of these, were covered with over of tephra and had to be abandoned, while received a tephra cover exceeding and suffered heavy damage as a result. The events and impact of the eruption may have stopped the settlement of the island and could have played a role in stimulating the Christianization of Iceland. However, it is possible that Iceland's population at the time was more resilient than during the 18th century and thus the Eldgjá event had less impact than the Laki eruption. Unlike the local impacts on Iceland, the effects of the Eldgjá eruption on Europe appear in the historical record. Darkened skies were reported from Germany, Ireland, Italy, Portugal and Spain although the interpretation of contemporary reports as referencing atmospheric phenomena linked to the Eldgjá eruption is controversial. Reportedly, winters in Europe and China between 939-942 were severe, with the sea and canals freezing, while
drought A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D.  Jiang, A.  Khan, W.  Pokam Mba, D.  Rosenfeld, J. Tierney, ...
s occurred during the summer months. Food crises reported in China, the
Maghreb The Maghreb (; ), also known as the Arab Maghreb () and Northwest Africa, is the western part of the Arab world. The region comprises western and central North Africa, including Algeria, Libya, Mauritania, Morocco, and Tunisia. The Maghreb al ...
, the
Levant The Levant ( ) is the subregion that borders the Eastern Mediterranean, Eastern Mediterranean sea to the west, and forms the core of West Asia and the political term, Middle East, ''Middle East''. In its narrowest sense, which is in use toda ...
and Western Europe at that time have been linked to the Eldgjá eruption. More tentatively, the downfall of the Later Jin Dynasty and
locust Locusts (derived from the Latin ''locusta'', locust or lobster) are various species of short-horned grasshoppers in the family Acrididae that have a swarming phase. These insects are usually solitary, but under certain circumstances they b ...
plagues in China,
epidemic An epidemic (from Greek ἐπί ''epi'' "upon or above" and δῆμος ''demos'' "people") is the rapid spread of disease to a large number of hosts in a given population within a short period of time. For example, in meningococcal infection ...
s of animal diseases in Europe and a decrease of human activity on Ireland and rebellions in Japan have been connected to the Eldgjá eruption.


Impacts of a repeat

Large fissure-fed effusive eruptions in Iceland reoccur every few centuries. The much smaller () 2010 eruption of Eyjafjallajökull caused worldwide disruptions of
air travel Air travel is a form of travel in vehicles such as airplanes, jet aircraft, helicopters, hot air balloons, blimps, Glider (aircraft), gliders, Hang gliding, hang gliders, parachuting, parachutes, or anything else that can sustain flight.
, with economic losses of over $1 billion for airlines alone, because
volcanic ash Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, produced during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to r ...
can interfere with the operation of airplane engines. Additional hazards of a widespread aerosol layer are its
corrosive Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...
effects on equipment, decreased visibility leading to accidents on the sea, as well as health hazards resulting from the aerosols. The impact could extend to North Africa.


See also

*
Geography of Iceland Iceland is an island country at the confluence of the Atlantic Ocean, North Atlantic and Arctic Ocean, Arctic oceans, east of Greenland and immediately south of the Arctic Circle, atop the constructive boundary of the northern Mid-Atlantic Ridg ...
*
Glacial lake outburst flood A glacial lake outburst flood (GLOF) is a type of outburst flood caused by the failure of a dam containing a glacial lake. An event similar to a GLOF, where a body of water contained by a glacier melts or overflows the glacier, is called a j� ...
* Iceland hotspot * Iceland plume * List of glaciers of Iceland *
List of lakes of Iceland Iceland has over 20 lakes larger than 10 km2 (4 sq mi), and at least 40 others varying between 2.5 and 10 km2 (1 to 4 sq mi) in size. This list also includes a few smaller lakes and ponds that are considered notable (for example Tjörnin ...
* Timeline of volcanism on Earth * Volcanism of Iceland **
List of volcanic eruptions in Iceland This is an incomplete list of volcanic eruptions in Iceland. Please see External links below for databases of Icelandic eruptions which include over 530 events. ''For latest information about the current/ongoing series of eruptions near Grindav ...
** List of volcanoes in Iceland


References


Sources

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External links

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Information on volcanism in the area
{{DEFAULTSORT:Eldgja Active volcanoes Canyons and gorges of Iceland East Volcanic Zone of Iceland Fissure vents Katla (volcano) Mountains of Iceland VEI-6 volcanoes Volcanoes of Iceland