Grímsnes

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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 64.03°N
  • 20.87°W

  • 214 m
    702 ft

  • 371060
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

The Global Volcanism Program has no activity reports for Grímsnes.

The Global Volcanism Program has no Weekly Reports available for Grímsnes.

The Global Volcanism Program has no Bulletin Reports available for Grímsnes.

Grímsnes is a relatively small volcanic system located SE of Thingvallavatn lake. The Grímsnes volcanic system is displaced about 15-20 km to the east of the other en echelon group of volcanic fields of the Western Volcanic Zone extending across the Reykjanes Peninsula. Grímsnes lava flows cover 54 sq km and were erupted from a group of 11 fissures that produced a series of NE-SW-trending crater rows. The eruptions of the basaltic Grímsnes lavas were considered to have been restricted to a relatively short interval between about 6500 and 5500 years ago, but later work showed that some of the lava flows were radiocarbon dated at between about 7400 and 8900 years ago.

Summary of Holocene eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
3500 BCE (?) Unknown Confirmed 2 Tephrochronology Kalfsholar
3650 BCE (?) Unknown Confirmed 0 Tephrochronology Borgarholar
3750 BCE (?) Unknown Confirmed 0 Tephrochronology Raudholar
3900 BCE (?) Unknown Confirmed 0 Tephrochronology Kolgrafarholl
4000 BCE (?) Unknown Confirmed 2 Tephrochronology Alftarholl
4050 BCE (?) Unknown Confirmed 0 Tephrochronology Borgaholl
4270 BCE ± 150 years Unknown Confirmed 3 Radiocarbon (uncorrected) Kerholar
4450 BCE (?) Unknown Confirmed 2 Tephrochronology Selholl North
4500 BCE (?) Unknown Confirmed 0 Tephrochronology Selholl South
6250 BCE (?) Unknown Confirmed   Radiocarbon (corrected)
7750 BCE (?) Unknown Confirmed 3 Radiocarbon (corrected) Seydisholar

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.



Cones
Feature Name Feature Type Elevation Latitude Longitude
Borgarholar Cone
Kolgrafarholl Cone


Craters
Feature Name Feature Type Elevation Latitude Longitude
Alftarholl Crater 64° 1' 0" N 20° 58' 0" W
Kalfsholar Crater Row 64° 3' 0" N 20° 55' 0" W
Kerholl Crater 64° 3' 0" N 20° 50' 0" W
Kerid Maar
Kerlingarholl Crater Row 64° 5' 0" N 20° 50' 0" W
Raudholar Crater 64° 2' 0" N 20° 56' 0" W
Selholl North Crater Row 64° 5' 0" N 20° 54' 0" W
Selholl South Crater 64° 5' 0" N 20° 54' 0" W
Seydisholar Crater Row 64° 4' 0" N 20° 50' 0" W
Tjarnarholar Crater Row 64° 2' 0" N 20° 54' 0" W
Grímsnes is a relatively small volcanic system located SE of Thingvallavatn lake east of an en echelon group of volcanic fields extending across the Reykjanes Peninsula. The Grímsnes volcanic field is seen here in an aerial view from the SW. Grímsnes lava flows cover 54 sq km and were erupted from a group of 11 fissures that produced a series of NE-SW-trending crater rows, such as seen at the lower right. The eruptions of the Grímsnes lavas were restricted to a relatively short interval between about 6500 and 5500 years ago.

Photo by Oddur Sigurdsson, 1991 (Icelandic National Energy Authority).
A small pond fills the bottom of the Kerid crater at the northern end of the Tjarnarholar crater row in the Grímsnes volcanic system. The crater is elliptic in shape, 270 m long, 170 m wide, and 55 m deep. Other cinder cones of the Holocene Grímsnes volcanic field are visible in the background to the north. Grímsnes lava flows cover 54 sq km and were erupted from a group of 11 fissures that produced a series of NE-SW-trending crater rows.

Photo by Lee Siebert, 2008 (Smithsonian Institution).

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title.

Gudmundsson A T, 1986b. Iceland-Fires. Reykjavik: Vaka-Helgafell, 168 p.

Jakobsson S P, 1966. The Grimsnes lavas SW-Iceland. Acta Nat Islandica, 2: 6-30.

Jakobsson S P, 1976. The age of the Grimsnes lavas. Natturufraedingurinn, 46: 153-162 (in Icelandic).

Sinton J, Gronvold K, Saemundsson K, 2005. Postglacial eruptive history of the Western Volcanic Zone, Iceland. Geochem Geophys Geosyst, 6(12): 10.1029/2005CG001021.

Steinthorsson S, et al., 2002. Catalog of Active Volcanoes of the World - Iceland. Unpublished manuscript.

Volcano Types

Crater rows
Maar

Tectonic Setting

Rift zone
Oceanic crust (< 15 km)

Rock Types

Major
Basalt / Picro-Basalt

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
6,253
6,253
11,236
197,798

Affiliated Databases

Large Eruptions of Grímsnes Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
WOVOdat WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
EarthChem EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).
Smithsonian Collections Search the Smithsonian's NMNH Department of Mineral Sciences collections database. Go to the "Search Rocks and Ores" tab and use the Volcano Name drop-down to find samples.