Английская Википедия:2023 Sundhnúkur eruption
Шаблон:Short description Шаблон:Use dmy dates Шаблон:Infobox eruption
On the evening of 18 December 2023, a volcanic eruption occurred at the Sundhnúkur crater chain north of the town of Grindavík, Iceland,[1][2] with lava spewing from fissures in the ground.[3] The intensity of the eruption and accompanying seismic activity decreased early on 19 December,[4] with lava seen spreading laterally from both sides of the newly opened fissures.[5] The eruption was described as the largest in the Reykjanes Peninsula since the beginning of eruptive activity in 2021,[5] and was visible as far away as the capital Reykjavík, 42 kilometers away.[6] The eruption ended on 21 December 2023, after the Icelandic Meteorological Office said no lava was erupting after a flight over the volcano, but clarified that it was "too early to declare the eruption over."[7] Sundhnúkur is a crater row and currently active volcanic fissure that is part of the Reykjanes Peninsula rift zone.[8]
The eruption was preceded by an intense earthquake swarm in the Eldvörp–Svartsengi volcanic system that began on 24 October 2023, caused by a magmatic intrusion underneath the area.[9] The frequency and intensity of the earthquakes dramatically increased on 10 November, with 20,000 tremors recorded by that time, the largest of which exceeded magnitude 5.3. An evacuation was ordered in Grindavík, and large-scale subsidence in and around the town is reported to have caused significant damage.[9]
Precursors
The 2023 earthquakes came nearly four years after volcanic activity began near the hyaloclastite mountain Þorbjörn, which indicated that the Reykjanes Peninsula was beginning a new volcanic cycle after 800 years of inactivity.[10] This is the fifth time a magmatic intrusion has formed in the Eldvörp-Svartsengi volcanic system since December 2019. Prior intrusions did not result in an eruption.[11] Previous volcanic unrest on the peninsula has mostly been associated with the Fagradalsfjall system, where three out of four confirmed magmatic intrusions have culminated in volcanic eruptions.[12][13][14][9]
Although earthquakes are a frequent occurrence in Iceland due to the island's location, straddling the Mid-Atlantic Ridge between the Eurasian and North American tectonic plates, the recent swarm was noted for being more extensive than usual.[15] A total of four volcanic eruptions have occurred in the Reykjanes Peninsula since 2021.[15]
The 2023 earthquake swarm is associated with a magmatic intrusion estimated to be up to Шаблон:Convert long that runs in a south-westerly direction, starting at Kálfellsheiði Шаблон:IPA-is and following the line of the Sundhnúkur Шаблон:IPA-is crater chain at a depth of around Шаблон:Convert. The largest of the earthquakes originated under the Sundhnúkur craters but subsequently propagated south-west under Grindavík and into the sea.[16] The town stands on lava erupted from Sundhnúkur around 2,350 years ago.[17] It is one of six communities on the peninsula that are situated on or near an eruptive fissure.[18]
October
An earthquake swarm began on the evening of 24 October due to the magmatic intrusion, with the intensity of the earthquakes decreasing by 30 October. Approximately 8,000 earthquakes were detected; most of these tremors occurred at a depth of Шаблон:Cvt.[9] The Icelandic Meteorological Office (IMO) reported that the swarm was focused around Eldvörp–Svartsengi, north of Grindavík.[19] Earlier in the month, the Reykjanes Peninsula experienced over 700 earthquakes, with the strongest reaching a magnitude of 3.3.[19]
November
The largest of the earthquakes to date reached magnitude 5.3 on 10 November.[20] By this time, over 22,000 earthquakes had been recorded since the beginning of the swarm in October.[21] The IMO predicted that an eruption was likely, stating that "it will take several days (rather than hours) for magma to reach the surface." The greatest extent of the magma intrusion was inferred to be around the Sundhnúkur crater chain, approximately Шаблон:Convert north of Grindavík. Instruments detected the presence of sulphur dioxide in the atmosphere on 14 November, indicating that magma was only a few hundred metres under the surface. Although the number of earthquakes decreased somewhat since 10 November, the IMO was still recording between 700–1,000 earthquakes daily by 14 November.[9]
Ground deformation sensors at Festarfjall Шаблон:IPA-is and Svartsengi recorded that the ground had moved apart by Шаблон:Cvt.[16] Satellite measurements recorded the subsidence by about Шаблон:Convert of a swathe of land measuring approximately five kilometres long and two kilometres wide (Шаблон:Convert), running from the Sundhnúkur craters to the western side of Grindavík. The creation of this graben-like formation has enabled scientists to estimate the volume of the magmatic intrusion as approximately Шаблон:Convert.[22] It is estimated that the subsidence has been continuing at a rate of about four centimeters (1.6 inches) a day.[23] A large crack opened up through the town, which old maps indicate is a reactivation of an existing fault. Scientists at the University of Iceland believe that the fault was created by the last Sundhnúkur eruption over 2,000 years ago.[24]
Sensors emplaced in a borehole in Svartsengi detected the presence of sulphur dioxide on 16 November, a classic signature of magma close to the surface. This led the IMO to conclude that the area around the volcanic edifice of Hagafell Шаблон:IPA-is, approximately Шаблон:Cvt north of Grindavík, is at the highest level of risk. A rapid Шаблон:Convert uplift of the ground in the Svartsengi area was recorded from 18–21 November, likely indicating an upwelling of magma from a source Шаблон:Convert below the ground. An eruption was still regarded as likely on 21 November, but as seismic activity declined from 24 November that likelihood also began to decline.[9]
According to Professor Magnús Tumi Guðmundsson, a geophysicist at the University of Iceland, the magma channel, approximately two meters wide, has undergone rapid solidification. Around 90% of the magma solidified within 10 to 15 days due to the cold nature of the earth's crust, with some remaining magma near Sundhnúkur posing potential risks for further activity if underground pressure increases. Magnús notes that while the magma cools quickly, the surrounding rock stays hot and weak, maintaining a state of geological vulnerability in the area for several months, necessitating ongoing caution and monitoring.[25] If an eruption occurs, it is most likely to take place in the area between Sýlingarfell Шаблон:IPA-is and Hagafell mountains.[26]
Significant land movements were recorded around the Svartsengi area, with a displacement of about Шаблон:Cvt to the west and Шаблон:Cvt to the north. During the evacuation of Grindavík on 10 November, the ground near Svartsengi initially descended by Шаблон:Cvt and subsequently rose by Шаблон:Cvt. A GPS station at Festarfjall, situated east of Grindavík, underwent a shift of Шаблон:Cvt eastward and Шаблон:Cvt southward, along with an upward movement of Шаблон:Cvt. Moreover, the GPS station in Grindavík, directly above the magma conduit, moved Шаблон:Cvt eastward. On 10 November, at the aforementioned location, there was also a dramatic drop of Шаблон:Cvt, followed by an additional sinking of Шаблон:Cvt.[27]
December
By 1 December "relatively few earthquakes" were being detected, although the IMO maintained that an eruption was still possible. It is most likely that the magma accumulating under Svartsengi is feeding the Шаблон:Convert Sundhnúkur crater chain, where the magma intrusion occurred. Deformations are still being measured at stations near the conduit, but it is believed that this is due to the land uplift occurring at Svartsengi.[9] At the beginning of the month, recent GPS data from the IMO showed that the land had risen above its level prior to the start of the earthquake series. Professor Þorvaldur Þórðarson, a volcanology expert from the University of Iceland, theorized that this elevation could be attributed to a combination of tectonic movements and magma build-up. Notably, the pronounced terrestrial shifts on 10 November may have facilitated the migration of magma from deeper reservoirs to more superficial ones.[28]
The ongoing volcanic activity at Svartsengi entered a new phase with increased chances of magma propagation and potential eruptions. The observed pattern suggested a possible repetition of events, where magma accumulating beneath Svartsengi feeds a dike beneath Grindavík, similar to the one formed on 10 November. The magma flow is now accumulating under Svartsengi at a rate comparable to the flow of the Elliðaár river. The magma lies at a depth of about Шаблон:Convert.[29]
The recent seismic trends at Svartsengi, characterized by varying intensities and a concentration of activity along a dike, closely resembled the seismic and volcanic patterns experienced during the Krafla Fires, which began in 1975. In the Krafla Fires the region witnessed over a period of ten years 20 distinct magma propagations, nine of which culminated in eruptions. These events were marked by varying magma volumes feeding the same dike, leading to different eruption scales. In Svartsengi, geodetic data showed a similar pattern of reduced magma volumes compared to levels observed before the 10 November dike intrusion, parallelling the smaller magma accumulations at Krafla that were sufficient to trigger new propagations and subsequent eruptions.[30]
From the beginning of the earthquakes until 10 November, the land at Svartsengi elevated by more than Шаблон:Convert within a span of 16 days. Following a substantial subsidence of Шаблон:Convert, a new phase of activity led to a land rise of Шаблон:Cvt over an equivalent 16-day period. Currently, the land has consistently ascended to about Шаблон:Cvt in approximately 30 days.[31] As a result, the rate of uplift went to double the initial rate and surpassed its height just before the precursor of the magmatic intrusion. The subsidence previously mentioned was due to the path of magma originating from Svartsengi, moving under Grindavík, and extending towards the Sundhnúkur craters in the northeast.[32]
Impact
Grindavík
Following the 5.2 tremor on 10 November, a state of emergency was declared, and evacuation plans were put into effect for Grindavík.[33] This culminated in the relocation of nearly 4,000 residents, equivalent to nearly 1 percent of Iceland's entire population.[34] The Department of Civil Protection and Emergency Management deployed the Icelandic Coast Guard Vessel Þór to the area "for safety purposes".[35] It also closed all roads to Grindavík except for emergency and evacuation purposes.[36] On 13 November, authorities allowed residents to return briefly to the town to retrieve their belongings.[37] Boat owners were also allowed to remove their vessels from the harbour. The Icelandic government is seeking to accommodate displaced residents in holiday homes and little-used properties while the emergency continues. The subsidence, faulting and earthquakes have caused widespread damage to properties and infrastructure in the town.[24] The seismic activity has received significant coverage by the international media.[38] The evacuation of Grindavík has been described as the first community-level evacuation in Iceland since the eruption of Heimaey in 1973.[23]
Prior to the evacuation, reports emerged of individuals relocating due to the incessant tremors disrupting sleep and fears of potential consequences. During the evacuation, the Icelandic Red Cross provided accommodations for about 1,700 displaced residents at three emergency centers in Keflavík, Kópavogur, and Selfoss. Of these individuals, approximately 140 actually spent the night in these centers. The majority of the other displaced residents independently found alternative accommodations elsewhere. Furthermore, every individual in the Grindavík area received an SMS message from 112, Iceland's emergency service, with the headline "EVACUATION".[39][40][41]
The Icelandic government plans to assist around 700 residents, who are part of about 200 families, from the original 3,700 population of Grindavík. The plan includes purchasing up to 210 new apartments through two non-profit housing associations, primarily in the Reykjanes area and the Capital Region. This is to be supplemented by temporary financial support for increased housing costs, with the entire support system estimated to cost about 220–240 million ISK per month, subject to a three-month reassessment. This initiative represents a comprehensive effort to provide both immediate and sustainable housing solutions for Grindavík's displaced residents.[42] On 1 December, the government, in partnership with the Government Property Agency, began seeking additional temporary rental properties from private and corporate owners to assist displaced Grindavík residents as part of a larger pre-established housing support program that includes wage and rental subsidies.[43] A week later, a platform for Grindavík residents was launched online, targeting temporary housing in the Reykjanes peninsula, the Capital Region, and neighboring municipalities. It enables direct leasing between residents and property owners, supported by government rental subsidies.[44]
In a collaborative response to the disaster and ongoing uncertainty in Grindavík, Iceland's major banks—Arion Banki, Íslandsbanki, and Landsbankinn, in partnership with the Financial Services Industry Association in Iceland—agreed to waive interest and indexation on housing loans for Grindavík residents for three months. This relief applies to loans up to 50 million ISK. The measure aims to provide equitable support, including options like deferred loan repayments. Each bank will further outline the specifics of these relief measures, ensuring they are tailored to the evolving needs of their customers in Grindavík.[45]
The State Commissioner of Police, in consultation with the Police Commissioner in the Reykjanes peninsula, downgraded the earthquake risk level in Grindavík from emergency to critical level, effective from 23 November. This decision, based on a new assessment by the Icelandic Meteorological Office, indicated a reduced likelihood of a sudden eruption in Grindavík. Residents and businesses in Grindavík are now permitted to enter the area between 7 a.m. and 9 p.m. to retrieve valuables, attend to their properties, and conduct business activities.[46] However, the town remains closed to the general public and unauthorized traffic. Safety measures, including limited vehicle access with restriction on certain types of transportation, constraints on essential services and a prepared evacuation plan, were established and are still in effect.[47] The area, under continuous surveillance, is still considered dangerous. Residents were advised to keep records of valuables taken and to contact their insurance companies, and to be cautious as houses might be unsafe. However, a resident of Grindavik was later caught staying at his home with his wife for several nights and was threatened with arrest.[3][48][49][50]
The earthquakes in Grindavík significantly affected infrastructure and homes. Around 120 properties suffered damage, with between 10 to 20 being deemed uninhabitable. Two weeks following the earthquakes, a thorough damage assessment was initiated and is currently ongoing. The estimated total cost of the damages is up to 10 billion ISK.[51] Property owners facing irreparable damage to their homes were obligated to allocate a segment of their insurance compensation—earmarked primarily for on-site repairs or reconstruction—to cover a disposal fee. In cases where rebuilding at the original location was not permitted, property owners were then allowed to use their insurance proceeds to buy homes elsewhere.[52][53]
Blue Lagoon
The management of the Blue Lagoon spa announced the site's closure to visitors from 9 November to 16 November as a precaution following the earthquakes.[54] Rocks dislodged by the earthquakes were reported to have fallen onto roads in the area while 30 guests left the resort following a 4.8 tremor in the early hours of 9 November. In addition to these safety concerns, the closure was also implemented to reduce increased stress on staff. The management has assured that all staff will receive their full salaries during the closure period. Furthermore, guests who were evacuated as a result of the tremor will be provided with a full refund.[55][56]
Helga Árnadóttir, CEO of the Blue Lagoon, confirmed that the seismic activity at Svartsengi caused no visible damage or structural impairment to their facilities. The buildings, designed for earthquake resilience, remained intact and structurally sound. Despite this, the Blue Lagoon temporarily ceased operations as a precautionary measure due to the earthquakes.[57]
The administrators of the Blue Lagoon subsequently extended the closure announcement five times due to continuing geological activity, with the anticipated reopening date set for 17 December.[58] Despite this, staff members of the Blue Lagoon were seen bathing in the spa's geothermal waters on 8 December.[59] Prior to reopening, the staff were trained in evacuation procedures to ensure preparedness for any emergencies, while the administration prepared an evacuation process, expected to take around two hours in case of emergency. Additionally, guests were to be informed about the current situation.[60][61][62][63]
The Blue Lagoon managed to remain open for just two days before a necessary closure ensued following the 18 December eruption that occurred merely 2 to 3 kilometers away. The anticipated reopening of the Blue Lagoon is scheduled for 28 December. All guests and staff were evacuated from the site roughly one to two hours before the eruption.[64][65]
Svartsengi Power Station
Since the state of emergency was declared, the Svartsengi Power Station has been unoccupied and is being remotely controlled from the Reykjanes Power Station.[66] The management of the power station expects to maintain this remote operation mode until the end of the year. The Reykjanes Power Station is equipped to generate electricity in case the Svartsengi line is cut off. The capability to deliver hot water, a critical function of the Svartsengi Power Station, cannot be replicated by the Reykjanes facility.[67][68]
The power station experienced minimal impact from the earthquakes on 10 November, with the only damages being "the interior furnishings and exterior walls, as well as considerable cracking in pathways and remote areas of the site." Despite these issues, the power station continued to maintain its usual production levels of hot and cold water, as well as electricity.[66]
Barrier construction
A strategic plan for the construction of protective barriers had been established well in advance of the recent seismic disturbances in the area.[12] The commencement of this plan was placed on hold, as there was no pressing threat of a volcanic eruption, coupled with the significant environmental repercussions involved. However, on 10 November, due to escalating earthquake activity, a fleet of lorries began delivering materials to the predetermined site near the Blue Lagoon and Svartsengi Power Station. Yet, this initial operation was soon put on hold owing to concerns about a potential eruption later that same day. The construction process was officially resumed on 13 November, following the Althing's approval of a bill proposed by Prime Minister Katrín Jakobsdóttir.[69] Subsequently, Justice Minister Guðrún Hafsteinsdóttir began enforcing the new regulations related to the project the next day.[70] Following this, workers began assembling filler materials into barriers at the planned sites.[71] The construction of the barriers was almost complete when the eruption occurred. Once it was safe for workers to resume, they were quickly sent back to the site to finish the remaining filling work on the barriers.[72]
Additional measures were also put in place, such as safeguarding power lines, although the construction of barriers for the Svartsengi Power Line was postponed until 2024 due to decreased volcanic activity. However, should the lava flow head towards the hot water line, protecting it without inflicting damage would be extremely challenging.[72][73]
In parallel, the civil defence department, equipped with plans for more protective barriers, made preparations to extend these measures to Grindavík if necessary.[74] Also under consideration is the construction of protective barriers for the town of Vogar, located in the northern part of the peninsula, after lava flow models indicated a chance of lava from the current eruption flowing north towards Route 41 (Reykjanesbraut) in the future. While Vogar and Route 41 are considered to have a low risk of being affected, Route 43 (Grindavíkurvegur), being closer to the lava front, faces a medium risk in this scenario, prompting additional concern for its safety.[75][76]
In response to these developments, the Icelandic government implemented a 0.008% additional property tax, levied on the fire insurance value of properties, to fund the construction of lava barriers on the Reykjanes peninsula and safeguard local infrastructure from potential volcanic eruptions. The temporary tax, which is intended to last for three years, will come into effect on 1 January 2024, and is projected to raise nearly ISK 1 billion annually. The tax is scheduled to expire on 31 December 2026.[69][77][78]
Eruption
Following the volcanic eruption on 18 December, the Icelandic Coast Guard deployed a helicopter to the area to monitor activity.[5] Numerous delays were reported at Keflavík International Airport, which remained open. The Blue Lagoon spa, which had reopened the day before, did not take bookings on the night of the eruption.[3] Police raised alert levels while civil defence authorities warned the public not to approach the area while emergency personnel assessed the situation.[79] By 19 December, the scent of smoke and ash was detected as far as Шаблон:Convert from the eruption site, raising fears that volcanic gases could reach Reykjavik by the next day.[80] On the same day, the Icelandic Coast Guard rescued a man who had gotten lost near the eruption site using a helicopter.[81] On 21 December, the IMO said no lava was erupting after a flight over the volcano, but clarified that it was "too early to declare the eruption over." Officials said residents of Grindavik would be allowed back into the town.[82]
The IMO said the eruption occurred at around 22:17 GMT following a series of small earthquakes at around 21:00.[83] It pinpointed the origin of the eruption near Hagafell,[84] about Шаблон:Convert north-east of Grindavik, and noted that the eruption stemmed from a fissure with a length of about 3.5 km, with lava flowing at a rate of around 100 to 200 cubic metres per second adding that seismic activity appeared to be moving towards the direction of Grindavik. An Icelandic Civil Defence official told the public broadcaster RÚV that the eruption had happened quickly and appeared to be "quite a large event".[6]
See also
- Geology of Reykjanes Peninsula
- List of earthquakes in 2023
- List of earthquakes in Iceland
- List of volcanic eruptions in Iceland
References
External links
- Icelandic Meteorological Office — Official website (in Icelandic)
- Шаблон:In lang Icelandic Meteorological Office — Official website
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