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{{Short description|Volcano in Iceland}}
{{About|the Langjökull volcanic system|the glacier|Langjökull}}
{{Infobox mountain
| name = Oddnýjarhnjúkur-Langjökull volcanic system
| other_name =Langjökull volcanic system, Hveravellir (northern-) and Skjaldbreiður (southern part)
| photo = Remote view of Langjökull from Road 35, Iceland, 20230501 0927 3767.jpg
| photo_caption = Langjökull from [[Route 35 (Iceland)|Route 35]]
| elevation_m = 1435
| elevation_ref={{sfn|Larsen|Guðmundsson|2019|loc=Central Volcano}}
| prominence =
| location = Southwestern [[Iceland]]
| coordinates = {{Coord|64.85|N|19.7|W|region:IS_type:mountain|format=dms|display=it}}
| coords_ref =<ref name=GVP/>
| type = [[Subglacial volcano|Subglacial]] [[central volcano]] with [[fissure vent|fissure swarm]]
| age = [[Holocene]]
|embedded= {{maplink|frame=yes|frame-align=center|frame-width=270|frame-height=240|frame-long=-19.8|frame-lat=64.6|zoom=7|raw=[{{Wikipedia:Map data/Askja}},{{Wikipedia:Map data/Grímsvötn}},{{Wikipedia:Map data/Öræfi volcanic belt}},{{Wikipedia:Map data/Hofsjökull}},{{Wikipedia:Map data/Katla}},{{Wikipedia:Map data/Hengill}},{{Wikipedia:Map data/Snæfellsnes volcanic belt}}]
|text=Selected geological features near the Langjökull volcanic system (red outlines). {{Wikipedia:Map data/Askja/key}}
}}
}}
The '''Oddnýjarhnjúkur-Langjökull''' ('''Langjökull''') volcanic system of Iceland last erupted about 3600 years ago and is associated with current geothermal activity. The area of its [[central volcano]] is at present under the second largest ice cap in Iceland.
== Geography ==
The volcanic system is located north of [[Þingvallavatn|Lake Thingvallavatn]] and its southern lava flows contribute to the floor of the [[Þingvellir]] [[rift valley]] central to Icelandic cultural history and the [[fissure vent|fissure system]] which is up to {{cvt|20|km}} wide extends up to {{cvt|100|km}} north.{{sfn|Larsen|Guðmundsson|2019|loc=Short Description}} The Laugarfjall lava dome on the western side of the [[Haukadalur]] valley that houses the [[Geysir]] geothermal area with its [[geyser]]s and other geothermal features is part of the southern fissure swarm. The [[shield volcano]] of [[Skjaldbreiður]] is prominent to the north of the rift valley with a height of {{cvt|1066|m}}<ref name=NLSI/> and to the north the [[Langjökull]] ice cap covers its central volcano of Oddnýjarhnjúkur. The highest point within the Langjökull icecap is to its north east where the Baldjökull part of the ice cap covers a [[tuya]] of the same name with a height of {{convert|1435|m|ft}}{{sfn|Larsen|Guðmundsson|2019|loc=Central Volcano}}. The geothermal area of [[Hveravellir]] with [[hot spring]]s, [[fumarole]]s and [[mud pool]]s is to the north east of the central volcano in the northern part of the fissure swarm which is dominated by Kjalhraun at {{convert|840|m|ft}}{{sfn|Larsen|Guðmundsson|2019|loc=Detailed Description:2. Morphology and topography}}. To the west is the [[Prestahnúkur]] volcanic system with the small ice cap of [[Eiríksjökull]] and to the east of Langjökull is the [[Hofsjökull volcanic system]] with the large [[Hofsjökull]] ice cap and to its south the [[Kerlingarfjöll]] volcanic massif. A large tuya Hrútfell with a height of {{cvt|1396|m}} is located between Baldjökull and Kerlingarfjöll at the southern end of the [[Kjölur]] plateau between the two volcanic systems which is reached by the [[Route 35 (Iceland)|Kjalvegur road (F35)]].
== Activity ==
Currently apart from the geothermal activity already mentioned at Geysir and Hveravellir there have been earthquake swarms to the south-east of the Langjokull glacier and north of Hveravellir.{{sfn|Hjartardóttir|Einarsson|Björgvinsdóttir|2016|pp=40–41}} While the Hallmundarhraun eruption of 950 CE took place from vents immediately adjacent to the north-west boundary of the system this eruption is now usually assigned to the Prestahnúkur volcanic system.{{sfn|Sæmundsson|2019}}. However the global volcanism program has maintained its historic assignment to the Oddnýjarhnjúkur-Langjökull system<ref name=GVP/>.
== Geology ==
The Oddnýjarhnjúkur-Langjökull volcanic system is mountainous as it has ice age subglacially erupted tuyas and [[tindar]]s up to {{cvt|10|km}} long, with post glaciation lava shields and volcanic fissures with the predominant lava being [[olivine]] [[tholeiite basalt]]. Only effusive eruptions have been identified. The Oddnýjarhnjúkur central volcano has caldera structures that have at their rim silicic hyaloclastite that formed during the ice age.{{sfn|Larsen|Guðmundsson|2019|loc=Detailed Description:1. Geological setting and tectonic context, 2. Morphology and topography}} The oldest deposits are about 800,000 years old.{{sfn|Larsen|Guðmundsson|2019|loc=Detailed Description:4. Eruption history and pattern}}
The Skjaldbreiður lava shield has three lava units deposited between 6000 and 9000 years [[before present|BP]],{{sfn|Hjartardóttir|Einarsson|2015|p=93}} and covers {{cvt|170|km2}} with a volume of about {{cvt|13|km3}}.{{sfn|Larsen|Guðmundsson|2019|loc=Detailed Description:2. Morphology and topography}}. It is sometimes considered a separate volcanic system with the southern fissures having erupted lavas with ages between 10,200 years and the most recent in the Oddnýjarhnjúkur-Langjökull volcanic system of 3600 years ago.{{sfn|Larsen|Guðmundsson|2019|loc=Detailed Description:4. Eruption history and pattern}}
The 7800 years BP Kjalhraun flow to the north-east has a similar area but covers only {{cvt|11|km3}} with its eastern portion broken up by faulting from the [[Hofsjökull volcanic system]].{{sfn|Hjartardóttir|Einarsson|2015|p=93}}{{sfn|Hjartardóttir|Einarsson|2021|loc=Fig. 1., 3. Geological settings}} On the Kjalhraun flow's northern edge is the Hveravellir high-temperature geothermal field with an area of {{cvt|2.5|km2}}.{{sfn|Larsen|Guðmundsson|2019|loc=Detailed Description:2. Morphology and topography}}
===Tectonics===
As part of the [[West volcanic zone of Iceland|Western volcanic zone]] of Iceland which is a receding rift, and the north–western edge of the [[Hreppar microplate]], the Oddnýjarhnjúkur-Langjökull volcanic system does not accommodate currently as much of the mutual movement of the [[North American Plate]] and [[Eurasian Plate]] as the volcanic zones to its south or east. The Western volcanic zone is an ultra-slow divergent spreading center, spreading at about {{cvt|7|mm}}/year at the [[Hengill]] triple junction at its south and with no spread where the [[Mid-Iceland belt]] which is the northern boundary of the Hreppar microplate meets the Western volcanic zone at Langjökull.{{sfn|Hjartardóttir|Einarsson|Björgvinsdóttir|2016|p=41}} The closeness of the [[Iceland hotspot]] to the east is believed to increase the magma supply.{{sfn|Hjartardóttir|Einarsson|Björgvinsdóttir|2016|p=39}}
== References ==
{{Reflist|30em|refs=<ref name=GVP>{{cite gvp|name=Oddnýjarhnjúkur-Langjökull|vn=371080|access-date=2024-05-01}}</ref><ref name=NLSI>{{cite web|url =https://kortasja.lmi.is/mapview/|title=National Land Survey of iceland (kortasja)–Map Viewer|access-date=2024-05-01}}</ref>
}}
=== Sources ===
*{{Cite web| url = https://icelandicvolcanoes.is/?volcano=LAN| title =Oddnýjarhnjúkur-Langjökull Alternative name: Langjökull, Hveravellir (northern-) and Skjaldbreiður (southern part)| work = Catalogue of Icelandic Volcanoes| language = en| access-date = 2024-05-01|first1 =Guðrún|last1 =Larsen|first2 =Magnús T.|last2 =Guðmundsson|year =2019}}
*{{cite journal|last1 =Hjartardóttir|first1 =Á.R.|last2 =Einarsson|first2 =P.|year =2021|title =Tectonic position, structure, and Holocene activity of the Hofsjökull volcanic system, central Iceland.|journal =Journal of Volcanology and Geothermal Research|volume =417|page =107277|doi =10.1016/j.jvolgeores.2021.107277|bibcode =2021JVGR..41707277H}}{{rp|loc=Fig. 1., 3. Geological settings}}
*{{cite journal|last1 =Hjartardóttir|first1 =Á.R.|last2 =Einarsson|first2 =P.|last3 =Björgvinsdóttir|first3 =S.G.|year= 2016|title =Fissure swarms and fracture systems within the Western Volcanic Zone, Iceland–Effects of spreading rates|journal =Journal of Structural Geology|volume =91|pages =39-53|doi =10.1016/j.jsg.2016.08.007
|bibcode =2016JSG....91...39H}}
*{{cite journal|last1 =Hjartardóttir|first1 =Á.R.|last2 =Einarsson|first2 =P.|year =2015|title=The interaction of fissure swarms and monogenetic lava shields in the rift zones of Iceland|journal=Journal of Volcanology and Geothermal Research|volume =299|pages =91-102|doi =10.1016/j.jvolgeores.2015.04.001|bibcode =2015JVGR..299...91H}}
*{{cite web|url =https://icelandicvolcanoes.is/?volcano=PRE|title=Catalogue of Icelandic Volcanoes
restahnúkur Alternative name: Prestahnjúkur|first1 =Kristján|last1 =Sæmundsson|year =2019}}
== External links ==
* [https://icelandicvolcanoes.is/?volcano=LAN Oddnýjarhnjúkur-Langjökull] in the [[Catalogue of Icelandic Volcanoes]]
* {{cite gvp|name=Oddnýjarhnjúkur-Langjökull|vn=371080|access-date=2024-05-01}}
Okumaya devam et...
{{Short description|Volcano in Iceland}}
{{About|the Langjökull volcanic system|the glacier|Langjökull}}
{{Infobox mountain
| name = Oddnýjarhnjúkur-Langjökull volcanic system
| other_name =Langjökull volcanic system, Hveravellir (northern-) and Skjaldbreiður (southern part)
| photo = Remote view of Langjökull from Road 35, Iceland, 20230501 0927 3767.jpg
| photo_caption = Langjökull from [[Route 35 (Iceland)|Route 35]]
| elevation_m = 1435
| elevation_ref={{sfn|Larsen|Guðmundsson|2019|loc=Central Volcano}}
| prominence =
| location = Southwestern [[Iceland]]
| coordinates = {{Coord|64.85|N|19.7|W|region:IS_type:mountain|format=dms|display=it}}
| coords_ref =<ref name=GVP/>
| type = [[Subglacial volcano|Subglacial]] [[central volcano]] with [[fissure vent|fissure swarm]]
| age = [[Holocene]]
|embedded= {{maplink|frame=yes|frame-align=center|frame-width=270|frame-height=240|frame-long=-19.8|frame-lat=64.6|zoom=7|raw=[{{Wikipedia:Map data/Askja}},{{Wikipedia:Map data/Grímsvötn}},{{Wikipedia:Map data/Öræfi volcanic belt}},{{Wikipedia:Map data/Hofsjökull}},{{Wikipedia:Map data/Katla}},{{Wikipedia:Map data/Hengill}},{{Wikipedia:Map data/Snæfellsnes volcanic belt}}]
|text=Selected geological features near the Langjökull volcanic system (red outlines). {{Wikipedia:Map data/Askja/key}}
}}
}}
The '''Oddnýjarhnjúkur-Langjökull''' ('''Langjökull''') volcanic system of Iceland last erupted about 3600 years ago and is associated with current geothermal activity. The area of its [[central volcano]] is at present under the second largest ice cap in Iceland.
== Geography ==
The volcanic system is located north of [[Þingvallavatn|Lake Thingvallavatn]] and its southern lava flows contribute to the floor of the [[Þingvellir]] [[rift valley]] central to Icelandic cultural history and the [[fissure vent|fissure system]] which is up to {{cvt|20|km}} wide extends up to {{cvt|100|km}} north.{{sfn|Larsen|Guðmundsson|2019|loc=Short Description}} The Laugarfjall lava dome on the western side of the [[Haukadalur]] valley that houses the [[Geysir]] geothermal area with its [[geyser]]s and other geothermal features is part of the southern fissure swarm. The [[shield volcano]] of [[Skjaldbreiður]] is prominent to the north of the rift valley with a height of {{cvt|1066|m}}<ref name=NLSI/> and to the north the [[Langjökull]] ice cap covers its central volcano of Oddnýjarhnjúkur. The highest point within the Langjökull icecap is to its north east where the Baldjökull part of the ice cap covers a [[tuya]] of the same name with a height of {{convert|1435|m|ft}}{{sfn|Larsen|Guðmundsson|2019|loc=Central Volcano}}. The geothermal area of [[Hveravellir]] with [[hot spring]]s, [[fumarole]]s and [[mud pool]]s is to the north east of the central volcano in the northern part of the fissure swarm which is dominated by Kjalhraun at {{convert|840|m|ft}}{{sfn|Larsen|Guðmundsson|2019|loc=Detailed Description:2. Morphology and topography}}. To the west is the [[Prestahnúkur]] volcanic system with the small ice cap of [[Eiríksjökull]] and to the east of Langjökull is the [[Hofsjökull volcanic system]] with the large [[Hofsjökull]] ice cap and to its south the [[Kerlingarfjöll]] volcanic massif. A large tuya Hrútfell with a height of {{cvt|1396|m}} is located between Baldjökull and Kerlingarfjöll at the southern end of the [[Kjölur]] plateau between the two volcanic systems which is reached by the [[Route 35 (Iceland)|Kjalvegur road (F35)]].
== Activity ==
Currently apart from the geothermal activity already mentioned at Geysir and Hveravellir there have been earthquake swarms to the south-east of the Langjokull glacier and north of Hveravellir.{{sfn|Hjartardóttir|Einarsson|Björgvinsdóttir|2016|pp=40–41}} While the Hallmundarhraun eruption of 950 CE took place from vents immediately adjacent to the north-west boundary of the system this eruption is now usually assigned to the Prestahnúkur volcanic system.{{sfn|Sæmundsson|2019}}. However the global volcanism program has maintained its historic assignment to the Oddnýjarhnjúkur-Langjökull system<ref name=GVP/>.
== Geology ==
The Oddnýjarhnjúkur-Langjökull volcanic system is mountainous as it has ice age subglacially erupted tuyas and [[tindar]]s up to {{cvt|10|km}} long, with post glaciation lava shields and volcanic fissures with the predominant lava being [[olivine]] [[tholeiite basalt]]. Only effusive eruptions have been identified. The Oddnýjarhnjúkur central volcano has caldera structures that have at their rim silicic hyaloclastite that formed during the ice age.{{sfn|Larsen|Guðmundsson|2019|loc=Detailed Description:1. Geological setting and tectonic context, 2. Morphology and topography}} The oldest deposits are about 800,000 years old.{{sfn|Larsen|Guðmundsson|2019|loc=Detailed Description:4. Eruption history and pattern}}
The Skjaldbreiður lava shield has three lava units deposited between 6000 and 9000 years [[before present|BP]],{{sfn|Hjartardóttir|Einarsson|2015|p=93}} and covers {{cvt|170|km2}} with a volume of about {{cvt|13|km3}}.{{sfn|Larsen|Guðmundsson|2019|loc=Detailed Description:2. Morphology and topography}}. It is sometimes considered a separate volcanic system with the southern fissures having erupted lavas with ages between 10,200 years and the most recent in the Oddnýjarhnjúkur-Langjökull volcanic system of 3600 years ago.{{sfn|Larsen|Guðmundsson|2019|loc=Detailed Description:4. Eruption history and pattern}}
The 7800 years BP Kjalhraun flow to the north-east has a similar area but covers only {{cvt|11|km3}} with its eastern portion broken up by faulting from the [[Hofsjökull volcanic system]].{{sfn|Hjartardóttir|Einarsson|2015|p=93}}{{sfn|Hjartardóttir|Einarsson|2021|loc=Fig. 1., 3. Geological settings}} On the Kjalhraun flow's northern edge is the Hveravellir high-temperature geothermal field with an area of {{cvt|2.5|km2}}.{{sfn|Larsen|Guðmundsson|2019|loc=Detailed Description:2. Morphology and topography}}
===Tectonics===
As part of the [[West volcanic zone of Iceland|Western volcanic zone]] of Iceland which is a receding rift, and the north–western edge of the [[Hreppar microplate]], the Oddnýjarhnjúkur-Langjökull volcanic system does not accommodate currently as much of the mutual movement of the [[North American Plate]] and [[Eurasian Plate]] as the volcanic zones to its south or east. The Western volcanic zone is an ultra-slow divergent spreading center, spreading at about {{cvt|7|mm}}/year at the [[Hengill]] triple junction at its south and with no spread where the [[Mid-Iceland belt]] which is the northern boundary of the Hreppar microplate meets the Western volcanic zone at Langjökull.{{sfn|Hjartardóttir|Einarsson|Björgvinsdóttir|2016|p=41}} The closeness of the [[Iceland hotspot]] to the east is believed to increase the magma supply.{{sfn|Hjartardóttir|Einarsson|Björgvinsdóttir|2016|p=39}}
== References ==
{{Reflist|30em|refs=<ref name=GVP>{{cite gvp|name=Oddnýjarhnjúkur-Langjökull|vn=371080|access-date=2024-05-01}}</ref><ref name=NLSI>{{cite web|url =https://kortasja.lmi.is/mapview/|title=National Land Survey of iceland (kortasja)–Map Viewer|access-date=2024-05-01}}</ref>
}}
=== Sources ===
*{{Cite web| url = https://icelandicvolcanoes.is/?volcano=LAN| title =Oddnýjarhnjúkur-Langjökull Alternative name: Langjökull, Hveravellir (northern-) and Skjaldbreiður (southern part)| work = Catalogue of Icelandic Volcanoes| language = en| access-date = 2024-05-01|first1 =Guðrún|last1 =Larsen|first2 =Magnús T.|last2 =Guðmundsson|year =2019}}
*{{cite journal|last1 =Hjartardóttir|first1 =Á.R.|last2 =Einarsson|first2 =P.|year =2021|title =Tectonic position, structure, and Holocene activity of the Hofsjökull volcanic system, central Iceland.|journal =Journal of Volcanology and Geothermal Research|volume =417|page =107277|doi =10.1016/j.jvolgeores.2021.107277|bibcode =2021JVGR..41707277H}}{{rp|loc=Fig. 1., 3. Geological settings}}
*{{cite journal|last1 =Hjartardóttir|first1 =Á.R.|last2 =Einarsson|first2 =P.|last3 =Björgvinsdóttir|first3 =S.G.|year= 2016|title =Fissure swarms and fracture systems within the Western Volcanic Zone, Iceland–Effects of spreading rates|journal =Journal of Structural Geology|volume =91|pages =39-53|doi =10.1016/j.jsg.2016.08.007
|bibcode =2016JSG....91...39H}}
*{{cite journal|last1 =Hjartardóttir|first1 =Á.R.|last2 =Einarsson|first2 =P.|year =2015|title=The interaction of fissure swarms and monogenetic lava shields in the rift zones of Iceland|journal=Journal of Volcanology and Geothermal Research|volume =299|pages =91-102|doi =10.1016/j.jvolgeores.2015.04.001|bibcode =2015JVGR..299...91H}}
*{{cite web|url =https://icelandicvolcanoes.is/?volcano=PRE|title=Catalogue of Icelandic Volcanoes
restahnúkur Alternative name: Prestahnjúkur|first1 =Kristján|last1 =Sæmundsson|year =2019}}== External links ==
* [https://icelandicvolcanoes.is/?volcano=LAN Oddnýjarhnjúkur-Langjökull] in the [[Catalogue of Icelandic Volcanoes]]
* {{cite gvp|name=Oddnýjarhnjúkur-Langjökull|vn=371080|access-date=2024-05-01}}
Okumaya devam et...