A central volcano is a type of volcano formed by basalts and silica-rich volcanic rocks. They contain very few or no volcanic rocks of intermediate composition, such that they are chemically bimodal. Large silicic eruptions at central volcanoes often result in the formation of one or more calderas. Central volcanoes can be stratovolcanoes or shield volcanoes. [1]
Central volcanoes undergo periodic eruptions throughout their lifetime, which can span more than a million years. In Iceland, volcanic systems are normally named after an associated central volcano. [2] The largest known glaciovolcanic central volcano on Earth is Mount Haddington, a glacier-covered shield volcano on James Ross Island in Antarctica. [3] [4]
Situated in the Ódáðahraun lava field, Trölladyngja is the biggest of the Icelandic shield volcanoes, reaching a height of 1,460 metres (4,790 ft) above sea level, and rising almost 600 m (2,000 ft) above the surrounding desert and lava fields. It part of the Bárðarbunga volcanic system and has a volume of 15 km3 (3.6 cu mi) with some extensive lava flows to the north of Bárðarbunga.
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 lava, which travels farther and forms thinner flows than the more viscous lava erupted from a stratovolcano. Repeated eruptions result in the steady accumulation of broad sheets of lava, building up the shield volcano's distinctive form.
Iceland experiences frequent volcanic activity, due to its location both on the Mid-Atlantic Ridge, a divergent tectonic plate boundary, and being over a hotspot. Nearly thirty volcanoes are known to have erupted in the Holocene epoch; these include Eldgjá, source of the largest lava eruption in human history. Some of the various eruptions of lava, gas and ash have been both destructive of property and deadly to life over the years, as well as disruptive to local and European air travel.
Herðubreið is a tuya and composite volcano in the northern part of Vatnajökull National Park, Iceland. It is situated in the Highlands of Iceland at the east side of the Ódáðahraun desert and close to Askja volcano. The desert is a large lava field originating from eruptions of Trölladyngja and other shield volcanoes in the area. Herðubreið was formed beneath the ice sheet that covered Iceland during the last glacial period.
Kverkfjöll is a potentially active central volcano, fissure swarm, and associated mountain range situated on the northern border of the glacier Vatnajökull in Iceland.
Öræfajökull is an ice-covered volcano in south-east Iceland. The largest active volcano and the highest peak in Iceland at 2,110 metres (6,920 ft), it lies within the Vatnajökull National Park and is covered by part of the glacier.
An active volcano is a volcano that has erupted during the Holocene, is currently erupting, or has the potential to erupt in the future. A volcano that is not currently erupting but could erupt in the future is known as a dormant volcano. Volcanoes that will not erupt again are known as extinct volcanoes.
Lava lakes are large volumes of molten lava, usually basaltic, contained in a volcanic vent, crater, or broad depression. The term is used to describe both lava lakes that are wholly or partly molten and those that are solidified.
Volcanic activity is a major part of the geology of Canada and is characterized by many types of volcanic landform, including lava flows, volcanic plateaus, lava domes, cinder cones, stratovolcanoes, shield volcanoes, submarine volcanoes, calderas, diatremes, and maars, along with less common volcanic forms such as tuyas and subglacial mounds.
The volcanic history of the Northern Cordilleran Volcanic Province presents a record of volcanic activity in northwestern British Columbia, central Yukon and the U.S. state of easternmost Alaska. The volcanic activity lies in the northern part of the Western Cordillera of the Pacific Northwest region of North America. Extensional cracking of the North American Plate in this part of North America has existed for millions of years. Continuation of this continental rifting has fed scores of volcanoes throughout the Northern Cordilleran Volcanic Province over at least the past 20 million years and occasionally continued into geologically recent times.
The James Ross Island Volcanic Group is a stratigraphic unit of Cenozoic age distributed on James Ross Island and Vega Island of the James Ross Island group, the Tabarin and Trinity peninsulas of Graham Land and surrounding islands in the Prince Gustav and Antarctic sounds.
Dyngjufjöll. The Dyngjufjöll is a volcanic mountain range in the northeast of Iceland which belongs to the Askja volcanic system. Sometimes called Dyngjufjöll, it is part of the Vatnajökull National Park. The Askja caldera is also located there.