Katla () is a large

volcano A volcano is a rupture in the Crust (geology), crust of a Planet#Planetary-mass objects, planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and volcanic gas, gases to escape from a magma chamber below the surface. On Ear ...

in southern Iceland. It is very active; twenty eruptions have been documented between 930 and 1918, at intervals of 20–90 years. It has not erupted violently for years, although there may have been small eruptions that did not break the ice cover, including ones in 1955, 1999, and 2011. Prior eruptions have had a Volcanic Explosivity Index (VEI) of between 4 and 6 on a scale of 0 to 8. In comparison, the

Eyjafjallajökull Eyjafjallajökull (; ), 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 with a summit elevation of . The volcan ...

2010 eruption had a VEI of 4. Bigger VEI-5 eruptions are comparable to

Mount St. Helens Mount St. Helens (known as Lawetlat'la to the indigenous Cowlitz people, and Loowit or Louwala-Clough to the Klickitat) is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United St ...

1980 eruption, while significantly rarer VEI-6 eruptions would be comparable to

Krakatoa Krakatoa (), also transcribed (), is a caldera in the Sunda Strait between the islands of Java and Sumatra in the Indonesian province of Lampung. The caldera is part of a volcanic island group ( Krakatoa archipelago) comprising four islands. T ...

's 1883 eruption and

Mount Pinatubo Mount Pinatubo is an active stratovolcano in the Zambales Mountains, located on the tripoint boundary of the Philippine provinces of Zambales, Tarlac and Pampanga, all in Central Luzon on the northern island of Luzon. Its eruptive histor ...

's 1991 eruption. 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.

Geography and physical appearances

Katla is one of the largest

volcanoes A volcano is a rupture 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 often found where tectonic plates a ...

Iceland Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its s ...

. It is situated to the north of Vík í Mýrdal and to the east of the smaller

glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...

. Its peak reaches and is partially covered by the

Mýrdalsjökull Mýrdalsjökull (pronounced , Icelandic for "(the) mire dale glacier" or "(the) mire valley glacier") is an ice cap in the south of Iceland. It is to the north of Vík í Mýrdal and to the east of the smaller ice cap Eyjafjallajökull. Between t ...

glacier. The system has an area of . The

Eldgjá Eldgjá (, "fire canyon") is a volcano and a canyon in Iceland. Eldgjá is part of the Katla volcano; it is a segment of a long chain of volcanic craters and fissure vents that extends northeast away from Katla volcano almost to the Vatnajöku ...

canyon is part of the same volcanic system. The

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...

of the Katla volcano has a diameter of and is covered with of ice. The volcano normally erupts every 40–80 years. The flood discharge at the peak of an eruption in 1755 has been estimated at 200,000–400,000 m³/s (7.1–14.1 million cu ft/sec), comparable to the combined average discharge of the

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Mississippi Mississippi () is a state in the Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; and to the northwest by Arkansas. Miss ...

Nile The Nile, , Bohairic , lg, Kiira , Nobiin: Áman Dawū is a major north-flowing river in northeastern Africa. It flows into the Mediterranean Sea. The Nile is the longest river in Africa and has historically been considered the longest ...

, and

Yangtze The Yangtze or Yangzi ( or ; ) is the longest river in Asia, the third-longest in the world, and the longest in the world to flow entirely within one country. It rises at Jari Hill in the Tanggula Mountains (Tibetan Plateau) and flows ...

rivers (about 266,000 m³/s (9.4 million cu ft/sec)).

Etymology

The name ''Katla'' derives from the word '' ketill'' ("

kettle A kettle, sometimes called a tea kettle or teakettle, is a type of pot specialized for boiling water, commonly with a ''lid'', ''spout'', and ''handle'', or a small electric kitchen appliance of similar shape that functions in a self-contained ...

"), referring to the form of the volcano. ''Katla'' is also used as a female first name.

Prehistoric activity

It is thought that Katla is the source of Vedde Ash, more than of

tephra Tephra is fragmental material produced by a 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, they re ...

dated to 10,600 years BP found at a number of sites including Vedde in Norway, Denmark, Scotland, and North Atlantic cores.

Historic activity

Sixteen eruptions have been recorded for Katla since 930. The last major eruption started on 12 October 1918 and lasted for 24 days. It was likely a VEI-5 level eruption. The 1918 eruption resulted in extending the southern coast by 5 km due to laharic flood deposits. Its present dormancy is among the longest in known history. Minor ( VEI-1?) eruptions occurred in: Major eruptions occurred in: Location of Katlas caldera

Most of these eruptions resulted in glacial floods. The severe fissure eruption in 934 was one of the largest lava eruptions in the past 10,000 years. Before the

Hringvegur Route 1 or the Ring Road ( or ) is a national road in Iceland that circles the entire country. As a major trunk route, it is considered to be the most important piece of transport infrastructure in Iceland as it connects the majority of towns ...

(Iceland's Ring Road) was constructed in 1974, people feared traversing the plains in front of the volcano because of the frequent ''

jökulhlaup A jökulhlaup ( ) (literally "glacial run") is a type of glacial outburst flood. It is an Icelandic term that has been adopted in glaciological terminology in many languages. It originally referred to the well-known subglacial outburst flood ...

'' (or glacier bursts) and the deep river crossings. Especially dangerous was the glacier outburst that followed the eruption of 1918.

Present day activity

Katla has been showing signs of unrest since 1999, and geologists have concerns that it might erupt in the near future. Particularly, monitoring has been intensified following the March 2010 eruptions of a smaller neighbouring volcano, the

glacier. The eruption of this nearby long-dormant volcano in March and April 2010 prompted fears among some geophysicists that it might trigger an eruption at the larger and more dangerous Katla. In the past 1,000 years, all three known eruptions of Eyjafjallajökull have triggered subsequent Katla eruptions. Following the 2010 Eyjafjallajökull eruptions, on 20 April 2010 Icelandic President Ólafur Grímsson said "the time for Katla to erupt is coming close ... we celandhave prepared ... it is high time for European governments and airline authorities all over Europe and the world to start planning for the eventual Katla eruption". Increased earthquake activity has been noticed on Katla since the eruption at Eyjafjallajökull, but no other signs of an imminent eruption have been observed. These quakes are located mainly on the northwestern rim of the caldera. On 9 October 2010, a sudden rise in harmonic tremor was observed in the stations around Katla, a sign of a possible impending eruption. , volcanologists are continuing to monitor Katla, aware that any eruption from Katla following an eruption from Eyjafjallajökull has historically occurred within months of the latter. The Icelandic Meteorological Office updates its website with reports of quakes both at Eyjafjallajökull and Katla.

2011 activity

In 2011, geologic activity led many to speculate that a very small subglacial eruption had taken place. In June 2011, harmonic tremor was again detected at Katla volcano. A few days later, an earthquake swarm took place in the caldera, indicating magma movement inside the volcano, leading to increased fears of an eruption in the near future. On 8 and 9 July, another spike in harmonic tremors occurred, as a small eruption of Katla took place. Cracks formed on the glacier, as well as a cauldron. Icelandic media reported a small subglacial eruption might have started. On the morning of 9 July, a glacier flood was reported in the river Múlakvísl, and also later in the river Skálm. The bridge across Múlakvísl was destroyed as well as other parts of the road, Route 1, on the Icelandic ring road. Helicopter pilots flying over the glacier also reported cracks in the glacier. Scientists monitoring the activity said speculation that it was caused by a "very small" subglacial eruption lacked confirmation by visual or seismic evidence.

2016 and 2017 activity

Tremors were detected under Katla in late August 2016. A "Specialist Description" describing the activity on 29 August 2016 noted that there was:

... a seismic swarm in Mýrdalsjökull on the 29th of August with two events in the northern Katla caldera rim measured at magnitude 4.5. These are the biggest earthquakes in Katla volcano since 1977. Earthquake eruption checks confirmed that most earthquakes occurred between 0:40 and 1:50 PM. The big earthquakes were about thirty seconds apart at 1:47. They were followed by more than 50 aftershocks until 15:12 PM, when there was an earthquake of magnitude 3.3 and then the cycle and seismic activity in the region reduced again. No unrest was measured along these earthquakes. The geothermal has decreased in the following week and is now negligible.

An update written at 11 Sep 16:38 GMT reported:

Today, shortly before 14:00, a small earthquake swarm began in Mýrdalsjökull. The largest earthquakes of the swarm were of magnitude 3.3 and 3.0 at 16:12 and 15:57. More than 10 smaller earthquakes were detected in the swarm. All of the earthquakes were shallow and located in the caldera of Katla volcano. It is not unusual for seismic swarms of this type to occur in this area.

In February 2017, seismic activity at the volcano continued.

Images

Image:Myrdalsjökull glacier iceland 2005 1.JPG, The Mýrdalsjökull glacier in 2005 image: Myrdalsjökull glacier iceland 2005 3.JPG, The Mýrdalsjökull glacier in 2005

In popular culture

Katla is the subject of '' Katla'', an Icelandic TV series produced for

Netflix Netflix, Inc. is an American subscription video on-demand over-the-top streaming service and production company based in Los Gatos, California. Founded in 1997 by Reed Hastings and Marc Randolph in Scotts Valley, California, it offers a fi ...

References

External links

Katla
in the Catalogue of Icelandic Volcanoes
Volcanism 1

University of Iceland's Institute of Earth Sciences page about Katla

Webcams from Iceland, including Katla

Katla: preparedness for tourists

Icelandic Meteorological Office: Katla status

{{Authority control Subglacial volcanoes of Iceland Subglacial calderas Active volcanoes Mountains of Iceland VEI-6 volcanoes East Volcanic Zone of Iceland 20th-century volcanic events One-thousanders of Iceland Glaciers of Iceland Volcanic systems of Iceland Calderas of Iceland