Central volcano
A central volcano is a stratovolcano within a volcanic system if it shows frequent eruptions and emits both mafic , andesitic and rockite material. Central volcanoes are usually fed by magma chambers at shallow depths. The term is mainly used in Iceland and is used there especially for the largest volcanoes, which are characterized by collapsed calderas .
Relationship between central volcano and volcanic system
Together with the crevices and swarms of crevices that emanate from it in all possible directions, which can appear as intrusions or as craters and rows of craters forming on the earth's surface, as well as high-temperature areas , the central volcano forms a volcanic system that it ruled .
Belonging to a particular volcanic system is usually determined by the chemical composition of the igneous rock of craters and volcanic crevices. Despite the different composition of the magmas, volcanic systems have a kind of common “fingerprint” in individual cases. In addition, one concludes from the simultaneity of volcanic eruptions in the central volcano and in connected fissure systems on their affiliation, e.g. B. happened with the simultaneous eruptions of the Grímsvötn (central volcano) and the Lakikrater in 1783.
Central volcano Krafla in North Iceland with its own caldera, aerial view
Central volcano with caldera: Askja
Row of craters belonging to the Askja fissure system at Hafragilsfoss, Jökulsárgljúfur
Examples
Active central volcanoes are the Icelandic volcanoes Askja , Bárðarbunga , Krafla and Snæfellsjökull , but also Etna and Vesuvius in Italy . A particularly large central European volcano is the mountain range of the Monts du Cantal with its highest peak Plomb du Cantal in France , of which it is not exactly known whether it is to be regarded as extinct or not.
The volcanoes on Heimaey Island , especially Eldfell and Helgafell , are the youngest volcanoes in Iceland's eastern volcanic zone. They are not yet a central volcano, even if the volcanic structure and the composition of the magma already meet the definition. But they are too young and their eruption history is not pronounced enough. Therefore, they are identified as the future central volcano at the southern end of the volcanic zone.
Individual evidence
- ^ Agust Gudmundsson: Infrastructure and mechanics of volcanic systems in Iceland . In: Journal of Volcanology and Geothermal Research , Volume 64, Issues 1-2 (February 1995), pp. 1-22, doi: 10.1016 / 0377-0273 (95) 92782-Q
- ^ Halldór Kjartansson: The Icelandic basement , in: Ari Trausti Guðmundsson: Lebende Erde. Facets of the geology of Iceland. Reykjavík, Mál og menning, 2007, p. 41
- ^ Institute of Earth Sciences, Iceland: Krafla (engl.)
- ↑ Thor Thordarson, Armann Hoskuldsson: Iceland - Classic Geology third in Europe Harpenden, 2002, p 163
- ↑ Accessed: February 20, 2011, French ( Memento of November 17, 2008 in the Internet Archive )
- ↑ Hannes Mattssona, Ármann Höskuldsson: Geology of the Heimaey volcanic center, south Iceland: early evolution of a central volcano in a propagating rift? In: Journal of Volcanology and Geothermal Research , Volume 127, Issues 1-2 (September 2003), s. 55-71, doi: 10.1016 / S0377-0273 (03) 00178-1