Logo link to homepage

Krýsuvík-Trölladyngja

Photo of this volcano
  • Iceland
  • Iceland and Arctic Ocean
  • Crater rows
  • 1340 CE
  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 63.917°N
  • 22.067°W

  • 360 m
    1181 ft

  • 371030
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number
Most Recent Weekly Report: 28 April-4 May 2021 Citation IconCite this Report

IMO reported that the fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 28 April-4 May. According to a news source, activity at the S vent of the fifth cone, which had opened on 13 April with N and S vents, intensified at around 2030 on 26 April. Fountaining became more explosive and lava was jetted 40-50 m high. The lava-flow rate significantly increased; lava flowed S then E and descended a valley into Meradalir.

By 29 April activity had intensified at the fifth cone where lava ejections reached 250 m high, but had ceased at the others. By 1 May lava flows had traveled N in Meradalir and connected to the flows that had previously descended into the valley from a fissure that opened on 5 April. IMO noted that fountaining at the vent was steady until around 0000-0100 on 2 May when it became more pulsating. Resting periods of 1-2 minutes were punctuated by intense fountaining reaching 100-150 m high for periods of 8-12 minutes. Gas plumes with minor amounts of ash rose 800-900 m a.s.l. A news source noted that on 2 May lava fountains rose over 300 m, the highest to date, and were seen from Reykjavik. Ejecta set fire to vegetation on the hill to the S of the vent, causing a smoke plume. The Aviation Color Code remained at Orange due to the lack of ash and tephra emissions.

Sources: Icelandic Meteorological Office (IMO), Icelandic National Broadcasting Service (RUV)

Weekly Reports - Index


2021: February | March | April


28 April-4 May 2021 Citation IconCite this Report

IMO reported that the fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 28 April-4 May. According to a news source, activity at the S vent of the fifth cone, which had opened on 13 April with N and S vents, intensified at around 2030 on 26 April. Fountaining became more explosive and lava was jetted 40-50 m high. The lava-flow rate significantly increased; lava flowed S then E and descended a valley into Meradalir.

By 29 April activity had intensified at the fifth cone where lava ejections reached 250 m high, but had ceased at the others. By 1 May lava flows had traveled N in Meradalir and connected to the flows that had previously descended into the valley from a fissure that opened on 5 April. IMO noted that fountaining at the vent was steady until around 0000-0100 on 2 May when it became more pulsating. Resting periods of 1-2 minutes were punctuated by intense fountaining reaching 100-150 m high for periods of 8-12 minutes. Gas plumes with minor amounts of ash rose 800-900 m a.s.l. A news source noted that on 2 May lava fountains rose over 300 m, the highest to date, and were seen from Reykjavik. Ejecta set fire to vegetation on the hill to the S of the vent, causing a smoke plume. The Aviation Color Code remained at Orange due to the lack of ash and tephra emissions.

Sources: Icelandic Meteorological Office (IMO); Icelandic National Broadcasting Service (RUV)


21 April-27 April 2021 Citation IconCite this Report

IMO reported that the fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 21-27 April. A M 4.1 earthquake was recorded at 2305 on 21 April about 6 km WSW of the fissures and followed by several aftershocks; it was the largest on the Reykjanes Peninsula since 15 March, before the eruption began. The average lava-flow rate was calculated by the University of Iceland’s Institute of Earth Sciences using photographs most recently collected during an overflight on 26 April. They reported that during the previous five days the flow rate from all of the active craters averaged just over 6 cubic meters per second; the average rate during the 38 days of the eruption was 5.6 cubic meters per second. The area of the flow field was 1.13 square kilometers, the total volume was over 18.4 million cubic meters, with an average thickness of just over 16 m. The Aviation Color Code remained at Orange due to the lack of ash and tephra emissions.

Source: Icelandic Meteorological Office (IMO)


14 April-20 April 2021 Citation IconCite this Report

IMO reported that the fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 14-20 April. Lava flowed from about eight vents and the flow field continued to expand; on 14 April a new hiking trail (“A”) had been covered. Volcanic gas emissions were at dangerous levels during 14-15 April so the eruption site was closed to the public. At about 1500 on 17 April a new vent was confirmed to have opened. It was small and close to another crater, possibly the one that had opened on 13 April. Lava was not flowing from the northernmost crater (the first that had opened outside Geldingadalur) during 18-20 April.

The eruption had been ongoing for 30 days by 17 April. Based on a report from University of Iceland’s Institute of Earth Sciences, the average lava-flow rate during the first 17 days of the eruption was 4.5-5 cubic meters per second but had increased to 7 cubic meters per second over the previous 13 days. During 12-18 April the flow rate was closer to 8 cubic meters per second, a slight increase over the recent average. By 19 April the area of the flow field was 0.9 square kilometers and the total volume was over 14 million cubic meters.

IMO warned visitors that new fissures could open without adequate visible warning, especially in an area by Litla-Hrút, just S of Keilir, `where seismicity was concentrated. They also warned of increased gas emissions hazards. The Aviation Color Code remained Orange due to the lack of ash and tephra emissions.

Source: Icelandic Meteorological Office (IMO)


7 April-13 April 2021 Citation IconCite this Report

IMO reported that the fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 7-13 April. Lava from the third fissure flowed S into Geldingadalur and NE towards the Meradalir valley site. Flows from the three fissures connected into one flow field on 7 April. Another new fissure opened at around 0300 on 10 April, halfway between two existing fissures, and all four fissures were simultaneously active. Lava flowed towards Geldingadalur. Gas-rich emission plumes were visible in webcam images rising 1.1-1.3 km (3,600-4,300 ft) a.s.l. At least two new vents opened on 13 April based on webcam views. On 14 April IMO noted that lava was flowing from at least eight vents and unverified reports form the morning suggested two additional vents had opened. Sulfur dioxide gas flux was 29 kilograms per second, comparable to measurements collected during the previous few weeks.

IMO warned visitors that new fissures could open without adequate visible warning, especially in an area just S of Keilir, by Litla-Hrút, where seismicity was concentrated. They also warned of increased gas emissions hazards. The Aviation Color Code remained Orange due to the lack of ash and tephra emissions.

Source: Icelandic Meteorological Office (IMO)


31 March-6 April 2021 Citation IconCite this Report

IMO reported that the small eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 31 March-6 April. Video and visitor photographs showed spattering and lava fountaining from the two cones, and lava flows from both cones moved W and S within the Geldingadalur valley. A new fissure, 100-200 m long, opened about 700 m NE of the Geldingadalur cones around noon on 5 April. During a helicopter overflight, scientists observed a gas plume rising from the new fissure and a fast-moving lava flow descending into the Meradalir valley to the SE. On 6 April lava from the second fissure was advancing at a rate of 7 cubic meters per second; lava-flow rates at the Geldingadalir site averaged 5.5 cubic meters per second. Around midnight during 6-7 April a third fissure opened in between the first two; all three were oriented NE-SW. Earlier on 6 April field teams had observed a landslide in same area. Lava from the third fissure mostly flowed SW into Geldingadalur. The Aviation Color Code remained Orange due to the lack of ash and tephra emissions.

Sources: Icelandic Meteorological Office (IMO); Icelandic Coast Guard


24 March-30 March 2021 Citation IconCite this Report

IMO reported that the small eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula continued during 24-30 March. Video and visitor photographs showed that continuous spattering and lava fountaining resulted in the formation of a second large cone adjacent to the main cone. Lava flows from both cones moved W and S within Geldingadalur valley. On 25 and 29 March the extrusion rate from the cone was an estimated 5.8 and 5.3 cubic meters per second, respectively, based on the latest Pléiades image acquisition (LMI).

A gas plume on 25 and 29 March rose to 1 km (3,300 ft) a.s.l; no ash or tephra was produced. Minor seismicity continued around the Fagradalsfjall area. Video data showed that on the morning of 28 March the N part of the largest cone along the fissure collapsed. Sulfur dioxide flux was 18-19 kg/s and drifted predominantly S. The IMO periodically issued warnings about weather conditions that would cause high concentrations of volcanic gases to settle near the eruption site, causing hazardous conditions for visitors. The Aviation Color Code remained Orange due to the lack of ash and tephra emissions.

Sources: Icelandic Meteorological Office (IMO); Icelandic National Broadcasting Service (RUV)


17 March-23 March 2021 Citation IconCite this Report

IMO reported that a small eruption in the western part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, began at around 2045 on 19 March. The eruption was first visible in webcam images and confirmed by satellite data, and an orange glow in clouds on the horizon was seen from Reykjanesbaer and Grindavík (10 km SW). The Aviation Color Code was raised to Red. Reykjanesbraut, the main road from the capital region to Reykjanesbaer and the international airport at Keflavík, was closed.

A fissure, 500-700 m long, had opened on a slope in the Geldingadalur valley about 4.7 km N of the coast and just off the SE flank of Fagradalsfjall mountain. Small lava fountains rose as high as 100 m above the fissure, and by 1110 on 20 March, the lava had covered an area less than 1 square kilometer and was approximately 500 m across. The extrusion rate was an estimated 5 cubic meters per second. The Aviation Color Code was lowered to Orange because there was little to no ash production that would affect aircraft. Reykjanesbraut reopened, but Sudurstrandarvegur, the road along the S coastline, was closed between Grindavík and Thorlakshofn.

The eruption continued during 21-23 March with a consistent extrusion rate. About three cones had formed along the fissure; the tallest and widest was situated at the higher part of the fissure. Lava flows, mainly from the largest cone, fanned out to the NW, W, and SW, and also flowed S and fanned out to the E. Spatter was ejected above the cones. Video captured by visitors showed parts of the largest cone collapsing and rebuilding. The IMO periodically issued warnings about weather conditions that would cause high concentrations of volcanic gases to settle near the eruption site, causing hazardous conditions for visitors. IMO noted that through the night of 22-23 March night sulfur dioxide levels in Reykjavík had increased, though not to unsafe levels.

Source: Icelandic Meteorological Office (IMO)


10 March-16 March 2021 Citation IconCite this Report

IMO reported that seismicity in the Reykjanes Peninsula remained elevated with thousands of earthquakes recorded during 10-16 March, in the western part of the Krýsuvík-Trölladyngja volcanic system in the Fagradalsfjall fissure swarm area. About 16,500 earthquakes had been detected over the week. Some of the largest events, M 4.3-5.4 recorded during 10-12 and 14-15 March, were felt as far as Hvanneyri (97 km NNE of Grindavik), Hvolsvollur (110 km ESE of Grindavik), and Saudakrokur (250 NE of Grindavik). A few, short-lived pulses of tremor were also recorded. The magma intrusion continued to move SW along a fault between Keilir and Fagradalsfjall, and was as shallow as 1 km below the surface. GPS, satellite, and seismic data indicated that the intrusion had expanded S to Nátthaga, a valley just E of Borgarfjall and S of Fagradalsfjall, and was 3-5 km long. Ground fracturing was visible in the area above the intrusion. The Aviation Color Code for Krýsuvík remained at Orange.

Source: Icelandic Meteorological Office (IMO)


3 March-9 March 2021 Citation IconCite this Report

IMO reported that seismicity in the area between the Krýsuvík and Reykjanes-Svartsengi volcanic systems remained elevated during 4-10 March. GPS and InSAR data indicated that the intrusion was ongoing, with magma moving slowly SW along a fault between Keilir and Fagradalsfjall at depths of 2-6 km. Seismicity fluctuated during 6-7 March but continued to be elevated; the largest event was a M 5.1 on 7 March. The geophysical and satellite data on 8 March suggested that magma movement had decelerated over the past week, and was possibly as shallow as 1 km. A burst of seismicity was recorded around 0520 on 9 March, concentrated at the S end of the intrusion in an area that was most likely source of the magma. On 10 March IMO stated that more than 34,000 earthquakes had been detected during the past two weeks, a total larger than all of 2020 which was characterized as an unusually high year for seismicity. The Aviation Color Code for Krýsuvík remained at Orange.

Source: Icelandic Meteorological Office (IMO)


24 February-2 March 2021 Citation IconCite this Report

IMO reported that seismicity in the area between Krýsuvík and Reykjanes-Svartsengi volcanic systems remained elevated during 26 February-1 March. More than 6,000 earthquakes had been detected after a M 5.7 event was recorded at 1005 on 24 February; two of those events were above M 5. The earthquakes were distributed over a 25-km-long section of a N-S striking fault along the E-W striking plate boundary, primarily located between Keilir and Fagradalsfjall. GPS data showed 4 cm of horizontal displacement near the epicenter of the M 5.7 event. An InSAR interferogram showed left-lateral movement over a large section of the plate boundary. Tremor began to be recorded by several stations at 1425 on 3 March, in an area located 2 km SW of Keilir. The signals possibly indicated magma rising towards the surface and prompted IMO to raise the Aviation Color Code for Krýsuvík to Orange.

Source: Icelandic Meteorological Office (IMO)


17 February-23 February 2021 Citation IconCite this Report

IMO raised the Aviation Color Code for Krýsuvík to Yellow on 24 February based on recent increased seismicity. Intense seismic activity had been detected for the previous few days and since midnight through the generation of the report at 1107 more than 500 earthquakes had been recorded. At 1005 a M 5.7 earthquake occurred 5 km W of Krýsuvík and at 1027 a M 4.2 was located in Nupshlidarhals, less than 1 km NW of Krýsuvík. The seismic unrest was unusual for the area in the context of the unrest in the Reykjanes peninsula that began in January 2020.

Source: Icelandic Meteorological Office (IMO)


The Global Volcanism Program has no Bulletin Reports available for Krýsuvík-Trölladyngja.

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.

Eruptive History

There is data available for 11 Holocene eruptive periods.

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1340 (?) Unknown Confirmed 1 Tephrochronology Tradarfjöll
1325 (?) Unknown Confirmed 1 Tephrochronology Elborg vid Trolladyngju
1188 Unknown Confirmed 1 Historical Observations Mavahlidargigir
1151 Unknown Confirmed 1 Historical Observations Ogmundargigar and other vents
1075 ± 75 years Unknown Confirmed 0 Radiocarbon (uncorrected) Gvendarselsgigar
0900 (?) Unknown Confirmed 2 Tephrochronology Melholl, Afstapahraun
0190 BCE ± 75 years Unknown Confirmed 2 Radiocarbon (uncorrected) Obrinnisholar
1060 BCE ± 75 years Unknown Confirmed 0 Radiocarbon (uncorrected) Sandfellskofagigir
5290 BCE ± 150 years Unknown Confirmed 2 Radiocarbon (uncorrected) Burfell
6000 BCE (?) Unknown Confirmed 0 Tephrochronology Hrútagjár
8500 BCE (?) Unknown Confirmed 0 Tephrochronology Hagafell
Deformation History

There is data available for 3 deformation periods. Expand each entry for additional details.


Deformation during 2010 - 2011 [Uplift; Observed by GPS, InSAR]

Start Date: 2010 Stop Date: 2011 Direction: Uplift Method: GPS, InSAR
Magnitude: Unknown Spatial Extent: Unknown Latitude: Unknown Longitude: Unknown

Reference List: Michalczewska et al. 2012*.

Full References:

Michalczewska, K., S. Hreinsdottir, T. Arnadottir, S. Hjaltadottir, T. Agustsdottir, M. T. Gudmundsson, H. Geirsson, F. Sigmundsson, G. Gudmundsson, 2012. Inflation and deflation episodes in the Krisuvik volcanic system. (abstract V33A-2843), Fall AGU.

Deformation during 2009 - 2009 [Uplift; Observed by GPS, InSAR]

Start Date: 2009 Stop Date: 2009 Direction: Uplift Method: GPS, InSAR
Magnitude: Unknown Spatial Extent: Unknown Latitude: Unknown Longitude: Unknown

Reference List: Michalczewska et al. 2012*.

Full References:

Michalczewska, K., S. Hreinsdottir, T. Arnadottir, S. Hjaltadottir, T. Agustsdottir, M. T. Gudmundsson, H. Geirsson, F. Sigmundsson, G. Gudmundsson, 2012. Inflation and deflation episodes in the Krisuvik volcanic system. (abstract V33A-2843), Fall AGU.

Deformation during 2009 - 2010 [Subsidence; Observed by GPS, InSAR]

Start Date: 2009 Stop Date: 2010 Direction: Subsidence Method: GPS, InSAR
Magnitude: Unknown Spatial Extent: Unknown Latitude: Unknown Longitude: Unknown

Reference List: Michalczewska et al. 2012*.

Full References:

Michalczewska, K., S. Hreinsdottir, T. Arnadottir, S. Hjaltadottir, T. Agustsdottir, M. T. Gudmundsson, H. Geirsson, F. Sigmundsson, G. Gudmundsson, 2012. Inflation and deflation episodes in the Krisuvik volcanic system. (abstract V33A-2843), Fall AGU.

Emission History

There is no Emissions History data available for Krýsuvík-Trölladyngja.

GVP Map Holdings

The maps shown below have been scanned from the GVP map archives and include the volcano on this page. Clicking on the small images will load the full 300 dpi map. Very small-scale maps (such as world maps) are not included. The maps database originated over 30 years ago, but was only recently updated and connected to our main database. We welcome users to tell us if they see incorrect information or other problems with the maps; please use the Contact GVP link at the bottom of the page to send us email.


Title: Geomorphology of Iceland
Publisher: University of Goteborg, Dept Phys Geog
Country: Iceland
Year: 1984
Map Type: Geology (Geomorphology)
Scale: 1:1,750
Map of Geomorphology of Iceland

Title: Geographical Names of Iceland
Publisher: University of Goteborg, Dept Phys Geog
Country: Iceland
Year: 1984
Map Type: Unknown
Scale: 1:1,750
Map of Geographical Names of Iceland
Smithsonian Sample Collections Database

The following 2 samples associated with this volcano can be found in the Smithsonian's NMNH Department of Mineral Sciences collections, and may be availble for research (contact the Rock and Ore Collections Manager). Catalog number links will open a window with more information.

Catalog Number Sample Description Lava Source Collection Date
NMNH 115620 Tholeiite -- --
NMNH 115637 Olivine Tholeiite HRUTAGJARDYNGJA --
External Sites