[BREAKING] Vulkanen IJsland #26: Uitbarsting Reykjanes

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Op woensdag 26 juni 2024 17:29 schreef Frutsel het volgende:
Onderzoek: IJslandse vulkaanuitbarstingen kunnen decennialang aanhouden - https://nos.nl/l/2526239

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Op donderdag 18 juli 2024 17:31 schreef aloa het volgende:

[..]
https://www.ijsland-enzo.(...)spagina.asp?tabsel=0

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Strong glacial flood in Mýrdalsjökull, Aviation Color Code for Katla raised to Yellow, Iceland

A strong glacial flood began in Mýrdalsjökull, an ice cap atop the Katla volcano in southern Iceland, around 11:00 UTC on July 27, 2024. This event prompted authorities to raise the Aviation Color Code for Katla volcano to Yellow.

The glacial flood increased the flow rate of the Skálm River to more than 1 000 m3 (35 300 feet3), resulting in the destruction of part of the ring road and a bridge over the river.

The National Police Commissioner’s Public Defense declared a level of uncertainty in consultation with the police chief in South Iceland. Additionally, the Icelandic Met Office (IMO) raised the Aviation Color Code for Katla volcano to Yellow.

The flow had decreased significantly by 21:00 UTC on July 27, IMO reported, adding that there were no signs of runoff reaching Múlakvísl or other rivers from Mýrdalsjökull.

“The Norwegian Meteorological Agency continues to monitor the area and closely monitor unrest and seismic activity under the glacier. It can take up to 24 hours for the activity to return to what is known as ‘normal background activity’, so this scenario can be declared over,” IMO said.

There are no signs in the Norwegian Meteorological Agency’s data that a volcanic eruption caused the glacier run.

Although it was an unusually large run, this event was caused by geothermal heat in the glacier’s cauldrons.

A GPS meter located on Austmannsbunga shows clear signs that the changes measured in the caldera are a regular glacier run. However, it is unclear what caused more water to be released than is generally the case from such runs.

The Coast Guard went on a patrol flight with scientists from the Meteorological Office and the University of Iceland to investigate the situation. During that flight, it was confirmed that runoff only came from Sandfellsjökull and from there reached the course of the river Skálm. There was no visibility over Mýrdalsjökull to confirm which boilers the running water came from.

In an update posted at 12:00 UTC on July 28, IMO said the water level and electrical conductivity in Skálm has decreased considerably since July 27.

“Low seismic activity was measured under the glacier last night and night. In the morning, several earthquakes were recorded, the largest with a magnitude of 2.9 around 06:00 UTC [July 28]. There was no change in unrest as a result.

“If no further seismic activity or runoff turbulence is measured, no further runoff from Mýrdalsjökull is expected at this time. However, the National Weather Service continues to monitor the area closely,” IMO said.

As it happened after the big run in Múlakvísl in 2011, activity in Mýrdalsjökull can be expected to remain high with seismic activity and frequent smaller glacier runs this year that flow from the glacier.

All things considered, about 2 million m3 (70.6 million feet3) of water must be collected in Mýrdalsjökull’s cauldrons before it flows forward. Based on the first estimate of the size of the run in Skálm, it is many times more than in a traditional run.

“Scientists will analyze the collected data to get a better picture of what caused such a large run. But as was mentioned in the news yesterday, there are no signs in the Norwegian Meteorological Agency’s data that a volcanic eruption has caused a glacier run this time.”

Satellite images show that the well-known caldera on Mýrdalsjökull has subsided.

It may take several days for the flow in Skálm to return to normal for the time of year.

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Increased seismic activity in Svartsengi, Iceland signals new volcanic eruption

Rising seismic activity and land deformation patterns in Iceland’s Svartsengi area resemble those observed before the last eruption in the Sundhnúkur crater row, indicating a potential for a new volcanic eruption in the near term.

Seismic activity in the region has significantly increased over the past few weeks, with daily earthquake counts ranging from 60 to 80. Most of these earthquakes have occurred at depths of 2 – 4 km (1.2 – 2.5 miles), particularly between the Stóra-Skógfell and Grindavík regions.

These patterns are similar to those observed before previous magma movements and volcanic eruptions in the region, indicating an elevated risk of volcanic eruption



In the latest update, released by the Icelandic Meteorological Office (IMO) on August 13, volcanologists estimated that the volume of magma accumulating beneath Svartsengi exceeds 20 million m3 (706 million ft3) since the last eruption, which began on May 29.

This accumulation is accompanied by ongoing land uplift, albeit at a slower rate than previously observed. The continued deformation suggests increasing magma pressure beneath Svartsengi.

Despite the increased activity, the IMO’s hazard assessment remains unchanged from the previous week and will stay in effect until August 20.

The report outlines two primary scenarios for potential volcanic activity:

Scenario 1:

An eruption between Stóra-Skógfell and Sundhnúkur could occur with little warning, with a pre-eruption warning time potentially being less than 30 minutes. Lava could reach Grindavíkurvegur near Þorbjörn within 1.5 hours and Grindavíkurvegur near Svartsengi within 3 hours.

Scenario 2:
The likely precursor to this scenario could be an earthquake swarm starting near Stóra-Skógfell or Sýlingarfell and moving southwards, along with accelerated deformation and pressure variations in local boreholes.

The warning interval for the eruption could be longer than in Scenario 1, but its exact duration is uncertain and depends on the distance the magma travels to breach the surface. Once erupted, lava is expected to reach Nesvegur and Suðurstrandarvegur within approximately 1.5 hours and could block key escape routes on land within around 6 hours.

Lava could reach the sea east of Grindavík within 1.5 – 3 hours. The rapid cooling of lava upon entering the sea may lead to localized hazards, such as the release of ash and harmful gases like hydrochloric acid (HCl), making conditions within a 500 m (1 640 feet) radius life-threatening.

A magma intrusion that reaches south of Hagafell will likely cause significant fault movements in Grindavík. There is a possibility that lava could erupt within Grindavík. One scenario is that lava erupting from a vent north of the protective barriers at Grindavík could flow into existing fissures and then re-emerge within the town limits. Another scenario is the possibility of an eruptive fissure opening within Grindavík. However, in such a situation, a fissure would likely first open north of the town before opening within the town limits.