Eyjafjallajökull in the context of "Caldera"

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 refer to all explosive eruption products (correctly referred to as tephra), including particles larger than 2 mm. Volcanic ash is formed during explosive volcanic eruptions when dissolved gases in magma expand and escape violently into the atmosphere. The force of the gases shatters the magma and propels it into the atmosphere where it solidifies into fragments of volcanic rock and glass. Ash is also produced when magma comes into contact with water during phreatomagmatic eruptions, causing the water to explosively flash to steam leading to shattering of magma. Once in the air, ash is transported by wind up to thousands of kilometres away.

Due to its wide dispersal, ash can have a number of impacts on society including: animal and human health problems, disruption to aviation, disruption to critical infrastructure (e.g., electric power supply systems, telecommunications, water and waste-water networks, transportation), primary industries (e.g., agriculture), and damage to buildings and other structures.

Skógar (pronounced [ˈskouː(ɣ)ar̥] ), literally "forests", is a small Icelandic village with a population of roughly 25 located at the south of the Eyjafjallajökull glacier, in the municipality of Rangárþing eystra.

The area is known for its waterfall, Skógafoss, on the Skógá [ˈskouː(ɣ)ˌauː] river, which springs from 60 metres at the top of an eroded cliff. At Skógar is a folk museum, Skógasafn [ˈskouː(ɣ)aˌsapn̥], as well as a museum on transport in Iceland.

Mýrdalsjökull (pronounced [ˈmirˌtalsˌjœːkʏtl̥] , Icelandic for "(the) mire dale glacier" or "(the) mire valley glacier") is an ice cap on the top of the Katla volcano in the south of Iceland. It is to the north of the town of Vík í Mýrdal and to the east of the smaller ice cap Eyjafjallajökull. Between these two glaciers is the Fimmvörðuháls pass.

The glacier contributes to the most serious natural hazard area of Iceland.

Between March and June 2010 a series of volcanic events at Eyjafjallajökull in Iceland caused enormous disruption to air travel across Western Europe.

The disruptions started over an initial period of six days in April 2010. Additional localised disruption continued into May 2010, and eruptive activity persisted until June 2010. The eruption was declared officially over in October 2010, after 3 months of inactivity, when snow on the glacier did not melt. From 14 to 20 April, ash from the volcanic eruption covered large areas of Northern Europe. About 20 countries closed their airspace to commercial jet traffic and it affected approximately 10 million travellers.

In response to concerns that volcanic ash ejected during the 2010 eruptions of Eyjafjallajökull in Iceland would damage aircraft engines, the controlled airspace of many European countries was closed to instrument flight rules traffic, resulting in what at the time was the largest air-traffic shut-down since World War II. The closures caused millions of passengers to be stranded not only in Europe, but across the world. With large parts of European airspace closed to air traffic, many more countries were affected as flights to, from, and over Europe were cancelled.

An eruption on 14 April led to an initial uninterrupted shutdown over much of northern Europe from 15 to 23 April. Afterwards, airspace was closed intermittently in different parts of Europe in the following weeks, as the path of the ash cloud was tracked. The ash cloud caused further disruptions to air travel operations in Scotland and Ireland on 4 and 5 May and in Spain, Portugal, northern Italy, Austria, and southern Germany on 9 May. Irish and UK airspace closed again on 16 May and reopened on 17 May.

The Iceland hotspot is a hotspot that is partly responsible for the high volcanic activity that has formed the Iceland Plateau and the island of Iceland. It contributes to understanding the geological deformation of Iceland.

Iceland is one of the most active volcanic regions in the world, with eruptions occurring on average roughly every three years (in the 20th and 21st century until 2010 there were 45 volcanic eruptions on and around Iceland). About a third of the basaltic lavas erupted in recorded history have been produced by Icelandic eruptions. Notable eruptions have included that of Eldgjá, a fissure of Katla, in 934 (the world's largest basaltic eruption ever witnessed), Laki in 1783 (the world's second largest), and several eruptions beneath ice caps, which have generated devastating glacial bursts, most recently in 2010 after the eruption of Eyjafjallajökull.

Katla (Icelandic pronunciation: [ˈkʰahtla] ) is an active subglacial volcano in southern Iceland. This volcano has been very active historically with at least twenty documented major eruptions since 2920 BC. In its recent history though, Katla has been less active as the last major eruption occurred in 1918. These eruptions have had a Volcanic Explosivity Index (VEI) of between 4 and 5 on a scale of 0 to 8. In comparison, the Eyjafjallajökull 2010 eruption had a VEI of 4. Larger VEI-5 eruptions are comparable to Mount St. Helens 1980 eruption. These eruptions have produced very large glacial outburst floods. Several smaller (minor) events measuring VEI-1 and below have occurred since.

Katla is one of the largest volcanic sources of carbon dioxide (CO₂) on Earth, accounting for up to 4% of total global volcanic carbon dioxide emissions.

Subglacial eruptions, those of ice-covered volcanoes, result in the interaction of magma with ice and snow, leading to meltwater formation, jökulhlaups, and lahars. Flooding associated with meltwater is a significant hazard in some volcanic areas, including Iceland, Alaska, and parts of the Andes. Jökulhlaups (glacial outburst floods) have been identified as the most frequently occurring volcanic hazard in Iceland, with major events where peak discharges of meltwater can reach 10,000 – 100,000 m/s occurring when there are large eruptions beneath glaciers.It is important to explore volcano-ice interactions to improve the effectiveness of monitoring these events and to undertake hazard assessments. This is particularly relevant given that subglacial eruptions have demonstrated their ability to cause widespread impact, with the ash cloud associated with Iceland's Eyjafjallajökull eruption in 2010 resulting in significant impacts to aviation across Europe.