Global Volcanism Program

The Global Volcanism Program has no activity reports available for Grímsnes.

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

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

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

Basic Data

Volcano Number

Last Known Eruption

Elevation

Latitude
Longitude

371060

3500 BCE

200 m / 656 ft

64.05°N
20.883°W

Morphology

Volcano Landform
Cluster

Volcano Types
Volcanic field
Crater rows
Maar

Rock Types

Major
Basalt / Picro-Basalt

Tectonic Setting

Rift zone
Oceanic crust (< 15 km)

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km

6,253
6,253
11,236
197,798

Geological Summary

Grímsnes is a relatively small volcanic system located SE of Thingvallavatn lake. It 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. Its lava flows cover 54 km² and were erupted from a group of 11 fissures that produced a series of NE-SW-trending crater rows. The eruptions of its basaltic lavas were considered to have been restricted to a relatively short interval between about 6,500 and 5,500 years ago, but radiocarbon dating showed that some of the lava flows were emplaced between about 7,400 and 8,900 years ago.

References

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography.

Gudmundsson A T, 1986. 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. Geochemistry Geophysics Geosystems, 6: Q12009. https://doi.org/10.1029/2005CG001021

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 Unpublished manuscript.

Eruptive History

There is data available for 11 confirmed Holocene eruptive periods.

3500 BCE (?) Confirmed Eruption VEI: 2 (?)

Episode 1 | Eruption

Kalfsholar

3500 BCE (?) - Unknown

Evidence from Correlation: Tephrochronology

List of 5 Events for Episode 1 at Kalfsholar

Start Date	End Date	Event Type
- - - -	- - - -	Explosion
- - - -	- - - -	Lava flow
- - - -	- - - -	Cinder Cone
- - - -	- - - -	Tephra
3500 BCE (?)	- - - -	VEI (Explosivity Index)

3650 BCE (?) Confirmed Eruption VEI: 0

Episode 1 | Eruption

Borgarholar

3650 BCE (?) - Unknown

Evidence from Correlation: Tephrochronology

List of 2 Events for Episode 1 at Borgarholar

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Lava flow
	3650 BCE (?)	- - - -	VEI (Explosivity Index)

3750 BCE (?) Confirmed Eruption VEI: 0

Episode 1 | Eruption

Raudholar

3750 BCE (?) - Unknown

Evidence from Correlation: Tephrochronology

List of 2 Events for Episode 1 at Raudholar

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Lava flow
	3750 BCE (?)	- - - -	VEI (Explosivity Index)

3900 BCE (?) Confirmed Eruption VEI: 0

Episode 1 | Eruption

Kolgrafarholl

3900 BCE (?) - Unknown

Evidence from Correlation: Tephrochronology

List of 2 Events for Episode 1 at Kolgrafarholl

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Lava flow
	3900 BCE (?)	- - - -	VEI (Explosivity Index)

4000 BCE (?) Confirmed Eruption VEI: 2 (?)

Episode 1 | Eruption

Alftarholl

4000 BCE (?) - Unknown

Evidence from Correlation: Tephrochronology

List of 4 Events for Episode 1 at Alftarholl

Start Date	End Date	Event Type
- - - -	- - - -	Explosion
- - - -	- - - -	Lava flow
- - - -	- - - -	Cinder Cone
4000 BCE (?)	- - - -	VEI (Explosivity Index)

4050 BCE (?) Confirmed Eruption VEI: 0

Episode 1 | Eruption

Borgaholl

4050 BCE (?) - Unknown

Evidence from Correlation: Tephrochronology

List of 3 Events for Episode 1 at Borgaholl

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Lava flow	weak or small
- - - -	- - - -	Cinder Cone
4050 BCE (?)	- - - -	VEI (Explosivity Index)

4270 BCE ± 150 years Confirmed Eruption VEI: 3

Episode 1 | Eruption

Kerholar

4270 BCE ± 150 years - Unknown

Evidence from Isotopic: 14C (uncalibrated)

List of 5 Events for Episode 1 at Kerholar

Start Date	End Date	Event Type	Event Remarks
- - - -	- - - -	Explosion
- - - -	- - - -	Lava flow	violent, strong, or large
- - - -	- - - -	Cinder Cone
- - - -	- - - -	Tephra
4270 BCE ± 150 years	- - - -	VEI (Explosivity Index)

4450 BCE (?) Confirmed Eruption VEI: 2 (?)

Episode 1 | Eruption

Selholl North

4450 BCE (?) - Unknown

Evidence from Correlation: Tephrochronology

List of 4 Events for Episode 1 at Selholl North

Start Date	End Date	Event Type
- - - -	- - - -	Explosion
- - - -	- - - -	Lava flow
- - - -	- - - -	Cinder Cone
4450 BCE (?)	- - - -	VEI (Explosivity Index)

4500 BCE (?) Confirmed Eruption VEI: 0

Episode 1 | Eruption

Selholl South

4500 BCE (?) - Unknown

Evidence from Correlation: Tephrochronology

List of 2 Events for Episode 1 at Selholl South

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Lava flow
	4500 BCE (?)	- - - -	VEI (Explosivity Index)

6250 BCE (?) Confirmed Eruption

Episode 1 | Eruption

6250 BCE (?) - Unknown

Evidence from Isotopic: 14C (calibrated)

List of 2 Events for Episode 1

	Start Date	End Date	Event Type	Event Remarks
	- - - -	- - - -	Explosion
	- - - -	- - - -	Scoria

7750 BCE (?) Confirmed Eruption VEI: 3

Episode 1 | Eruption

Seydisholar

7750 BCE (?) - Unknown

Evidence from Isotopic: 14C (calibrated)

List of 4 Events for Episode 1 at Seydisholar

Start Date	End Date	Event Type
- - - -	- - - -	Explosion
- - - -	- - - -	Lava flow
- - - -	- - - -	Ash
7750 BCE (?)	- - - -	VEI (Explosivity Index)

Deformation History

There is no Deformation History data available for Grímsnes.

Emission History

There is no Emissions History data available for Grímsnes.

Photo Gallery

The small Grímsnes volcanic field is seen here in an aerial view from the southwest. A major road (Route 35) is seen running from the top to the bottom of the picture. To the east of this is the Tjarnarhólar crater row (bottom right), including the lake-filled Kerid Crater at the top. The Seyðishólar and Kerhóll cinder cones visible at top center formed about 9,500 and 7,050 years ago, respectively.

Photo by Oddur Sigurdsson, 1991 (Icelandic National Energy Authority).

A small pond about 60 x 100 m fills the bottom of the Kerid crater at the northern end of the Tjarnarhólar crater row in the Grímsnes volcanic system. The crater is elliptical in shape, 180 x 280 m. The Seyðishólar and Kerhóll cinder cones, visible in the background to the north, were active about 9,500 and 7,050 years ago respectively. Seyðishólar is the only Holocene eruption recognized to have had tephra dispersal outside of the volcanic field.

Photo by Lee Siebert, 2008 (Smithsonian Institution).

GVP Map Holdings

Maps are not currently available due to technical issues.

Smithsonian Sample Collections Database

There are no samples for Grímsnes in the Smithsonian's NMNH Department of Mineral Sciences Rock and Ore collection.

External Sites

Catalogue of Icelandic Volcanoes (Link to Grímsnes)

The Catalogue of Icelandic Volcanoes is an interactive, web-based tool, containing information on volcanic systems that belong to the active volcanic zones of Iceland. It is a collaboration of the Icelandic Meteorological Office (the state volcano observatory), the Institute of Earth Sciences at the University of Iceland, and the Civil Protection Department of the National Commissioner of the Iceland Police, with contributions from a large number of specialists in Iceland and elsewhere. This official publication is intended to serve as an accurate and up-to-date source of information about active volcanoes in Iceland and their characteristics. The Catalogue forms a part of an integrated volcanic risk assessment project in Iceland GOSVÁ (commenced in 2012), as well as being part of the effort of FUTUREVOLC (2012-2016) on establishing an Icelandic volcano supersite.

Copernicus Browser

The Copernicus Browser replaced the Sentinel Hub Playground browser in 2023, to provide access to Earth observation archives from the Copernicus Data Space Ecosystem, the main distribution platform for data from the EU Copernicus missions.

MIROVA

Middle InfraRed Observation of Volcanic Activity (MIROVA) is a near real time volcanic hot-spot detection system based on the analysis of MODIS (Moderate Resolution Imaging Spectroradiometer) data. In particular, MIROVA uses the Middle InfraRed Radiation (MIR), measured over target volcanoes, in order to detect, locate and measure the heat radiation sourced from volcanic activity.

MODVOLC Thermal Alerts

Using infrared satellite Moderate Resolution Imaging Spectroradiometer (MODIS) data, scientists at the Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, developed an automated system called MODVOLC to map thermal hot-spots in near real time. For each MODIS image, the algorithm automatically scans each 1 km pixel within it to check for high-temperature hot-spots. When one is found the date, time, location, and intensity are recorded. MODIS looks at every square km of the Earth every 48 hours, once during the day and once during the night, and the presence of two MODIS sensors in space allows at least four hot-spot observations every two days. Each day updated global maps are compiled to display the locations of all hot spots detected in the previous 24 hours. There is a drop-down list with volcano names which allow users to 'zoom-in' and examine the distribution of hot-spots at a variety of spatial scales.

WOVOdat
   Single Volcano View
   Temporal Evolution of Unrest
   Side by Side Volcanoes

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.

GVMID Data on Volcano Monitoring Infrastructure The Global Volcano Monitoring Infrastructure Database GVMID, is aimed at documenting and improving capabilities of volcano monitoring from the ground and space. GVMID should provide a snapshot and baseline view of the techniques and instrumentation that are in place at various volcanoes, which can be use by volcano observatories as reference to setup new monitoring system or improving networks at a specific volcano. These data will allow identification of what monitoring gaps exist, which can be then targeted by remote sensing infrastructure and future instrument deployments.

Volcanic Hazard Maps

The IAVCEI Commission on Volcanic Hazards and Risk has a Volcanic Hazard Maps database designed to serve as a resource for hazard mappers (or other interested parties) to explore how common issues in hazard map development have been addressed at different volcanoes, in different countries, for different hazards, and for different intended audiences. In addition to the comprehensive, searchable Volcanic Hazard Maps Database, this website contains information about diversity of volcanic hazard maps, illustrated using examples from the database. This site is for educational purposes related to volcanic hazard maps. Hazard maps found on this website should not be used for emergency purposes. For the most recent, official hazard map for a particular volcano, please seek out the proper institutional authorities on the matter.

IRIS seismic stations/networks

Incorporated Research Institutions for Seismology (IRIS) Data Services map showing the location of seismic stations from all available networks (permanent or temporary) within a radius of 0.18° (about 20 km at mid-latitudes) from the given location of Grímsnes. Users can customize a variety of filters and options in the left panel. Note that if there are no stations are known the map will default to show the entire world with a "No data matched request" error notice.

UNAVCO GPS/GNSS stations

Geodetic Data Services map from UNAVCO showing the location of GPS/GNSS stations from all available networks (permanent or temporary) within a radius of 20 km from the given location of Grímsnes. Users can customize the data search based on station or network names, location, and time window. Requires Adobe Flash Player.

DECADE Data

The DECADE portal, still in the developmental stage, serves as an example of the proposed interoperability between The Smithsonian Institution's Global Volcanism Program, the Mapping Gas Emissions (MaGa) Database, and the EarthChem Geochemical Portal. The Deep Earth Carbon Degassing (DECADE) initiative seeks to use new and established technologies to determine accurate global fluxes of volcanic CO₂ to the atmosphere, but installing CO₂ monitoring networks on 20 of the world's 150 most actively degassing volcanoes. The group uses related laboratory-based studies (direct gas sampling and analysis, melt inclusions) to provide new data for direct degassing of deep earth carbon to the atmosphere.

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).

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).