Opnieuw wordt een IJslandse vulkaan wakker / aviation code geel

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Gestart door 4seasons, zo 19 nov 2017 - 14:02

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Opnieuw lijkt het erop dat een slapende vulkaan in IJsland wakker wordt.
Ditmaal Öræfajökull.

CiteerDe Öræfajökull is een met ijs bedekt vulkanisch massief, dat deel uitmaakt van de Vatnajökull, de grootste gletsjer van Europa. De hoogste top van Öræfajökull is Hvannadalshnúkur. Met een hoogte van 2.119 meter is dit tevens het hoogste punt van IJsland.

De rivier de Stigá heeft zijn oorsprong in de Öræfajökull. In dit riviertje bevindt zich de Stigafoss, met een verval van 138 meter de één na hoogste waterval van IJsland.
Bron: Wikipedia

Maar er heerst grote onzekerheid omdat men weinig afweet van hoe de vulkaan zich zal gaan gedragen.
De laatste erupties waren in 1727 en daarvoor in 1362.
De aviation code is verhoogd naar geel.
De IJslandse dienst heeft ondertussen meetapparatuur geplaatst.

Hieronder de - tot nu toe - bekende gegevens/artikelen.
IMO (Icelandic Meteorological Office)
MBL Island
Iceland Monitor
Iceland Review

New seismic stations installed around Öræfajökull
In the last week of October, staff from IMO installed two new seismic stations near the glacier Öræfajökull: at Háöxl (Hox), south of the glacier; and at Kvísker (Kvi), on the eastern side of the glacier. In addition earlier in the month, IMO gained access to the seismic station, owned by the British Geological Society, located near Falljökull (Fal), west of Öræfajökull. This station, which was installed for ice-quakes research, has proofed to be very beneficial to locate earthquakes in this volcanic area.




Uncertainty about course of events at Öræfajökull volcano

Here you can see the new ice cauldron. Photo/Ágúst J. Magnússon

Although it's clear that there's a lot of geothermal heat underneath the Öræfajökull cauldron there are no signs of an iminent eruption.
Scientists are however, uncertain as to what exactly is going on.
Scientists from the geological department of the University of Iceland as well as from the Iceland Met Office and representatives of the Civil Protection management in Iceland flew across the glacier yesterday.
Samples from the rivers were also taken to measure gases and electrical conductivity.
The new ice-cauldron was measured and it's 1 km in diameter and 15-20 metres deep.
Water from the cauldron flows into Kvíá river. The aviation colour code remains yellow in the area.

New satellite images of Öræfajökull volcano showed on Friday night that a new ice-cauldron has formed within the caldera in the last week.
A pilot flying over the area took pictures of the cauldron today and sent them to the Icelandic Meteorological Office.
The cauldron is about 1 km in diameter and it reflects a recent increase in geothermal activity within the caldera.

It seems that geothermal water has been slowly released from underneath the cauldron to the glacial river of the Kvíárjökull outlet-glacier (SE flank of Öræfajökull volcano).
Associated with this water release sulphur smell has been reported nearby Kvíárjökull since last week.
Most of the water has probably already been released. An increase in the seismic activity has been recorded for the last few months, but for the past days it has been low.
This data indicates increased activity of the volcano which has not erupted since 1727. Currently there are no signs of an imminent eruption.
The Icelandic Meteorological Office has increased the surveillance of the area and is monitoring the volcano closely in collaboration with scientists from the University of Iceland and the Icelandic Civil Protection Authorities

Öræfajökull Volcano Possibly Awakening

Satellite images of Öræfajökull.
The image to the left was taken today, while the one to the right was taken on November 1st.Photo: Icelandic Met Office
By Geir Finnsson

Recent satellite images reveal that a new, one-kilometre wide caldera has emerged in Öræfajökull glacier, South Iceland, following increased geothermal activity in the area.
Earlier this week, the Icelandic Met Office received reports of a sulphur-odour in the area, which was later confirmed by the police. Such an odour usually indicates geothermal activity.
Geothermal water appears to have leaked slowly from beneath the caldera in the vicinity of Kvíárjökull glacier but most of it has probably already come out.
The Met Office has issued a yellow alert for Öræfajökull, which indicates that the volcano is showing more activity than normal.

According to Bryndís Ýr Gísladóttir at the Icelandic Met Office, this is done due to the fact that there isn't enough information on the volcano as of yet.
"We issued a yellow warning for security reasons because we actually don't know that much about Öræfajökull glacier nor how it behaves because its last eruption occurred in 1727, and 1362 before that."
Bryndís believes the volcano might be waking up from a long slumber.
During Iceland's settlement, the glacier was called Knappafellsjökull. Its 1362 eruption completely destroyed the nearby farms, renaming the glacier Öræfajökull. Öræfi translates to wasteland.

Rögnvaldur Ólafsson at the Department of Civil Protection and Emergency Management told Bylgjan that the yellow alert was issued primarily to keep the public informed. There are no signs of volcanic unrest as of yet.
"It's clear that there's more heat underneath the mountain than normally, at least enough to form a caldera that people haven't seen before.
So there's something happening there, although it is nothing special. There are no signs that indicate there's going to be an eruption."

Geologist Magnús Tumi Guðmundsson flew over the area earlier today. According to his findings, the caldera appears to be roughly 21-25 metre (68-82 ft) deep.
The caldera itself isn't very deep, but the deepening itself developed very quickly.
The area will continue to be monitored carefully.

Community Meeting Held Due To Increased Seismic Activity
The Department of Civil Protection and Emergency Management, as well as the Met Office, held a meeting with residents of Öræfar yesterday. RÚV reports.
Over 26 small earthquakes were detected under Öræfajökull glacier for the past 48 hours.
"The Met Office has placed more seismographs in the area and more similar devices are on their way.
Alongside this we've begun work at evacuation plans and other necessary work that we need to keep in mind if Öræfajökull starts to show any further signs," Víðir Reynisson at the Department of Civil Protection and Emergency Management told RÚV.

According to Víðir, Öræfajökull began to show increased seismic activity during the latter parts of the year.
The area contains one of the most active volcanoes in Iceland, and although there is no guarantee anything will happen, Víðir feels it important to always be prepared. "I always say that we ought to respect our volcanoes and maybe show them some fear as well."

Nearby residents appear to be quite calm over the situation, which is to be expected of anyone living near such an area. An evacuation plan ought to be finished early next year.
Öræfajökull has erupted two times over the past millennia. The last eruption was 290 years ago.
Although increased seismic activity is always a reason for caution, the chances of an eruption in the near future aren't necessarily high.

Yellow alert put up for Öræfajökull volcano
A new caldera, measuring a diameter of one kilometres has been formed in this last week in Öræfajökull glacier, a caldera spotted via satellite images of the glacier.
Iceland's volcanoes may be ready to blow
According to the Iceland Met Office this caldera shows increased activity in Öræfajökull which is located in Vatnajökull, Iceland's largest glacier.
A great sulphuric stench has eminated from the river Kvíá last week. 
Increased seismic activity has occured in the area in recent months, activity which has subsided in recent days. The volcano hasn't erupted since 1727. There are still no signs of an imminent eruption states an announcement from the Met Office. However, the safety code has been put up to yellow.
Iceland's volcanoes may be getting ready to blow
According to Páll Einarsson, geophysicist at the geological science department of the  University of Iceland believes that there are evident signs that some of Iceland's most famous volcanoes are becoming unrestful.
Interviewed by Morgunblaðið, Einarsson says that there is a process of action going on within these volcanoes which could very well end in an eruption in the course of time.
He adds that it is impossible to predict eruptions a long time ahead of them occurring but that they are under more surveillance than ever before
There has been increased pressure in both Bárðarbunga and Grímsvötn after the last eruptions, in both volcanoes, " says Einarsson. Both of these volcanoes are underneath Vatnajökull glacier and are both recharging and most probably preparing for the next chapter in volcanic activity.
The volcanic eruption in Holuhraun, which originated in the Bárðarbunga stratovolcano in 2014-2015 was considerably large. So was the eruption in Grímsvötn volcano in 2011 which was unusually large, the largest seen for decades.
Hekla, Iceland's most famous volcano, is also experiencing mounting pressure since its eruption in the year 2000.
"It would come as a surprise to no one if Hekla blows soon. It could also drag on for a while. We don't know how long volcanoes can endure expansion of gases without this coming to an eruption," says Einarsson.
Another volcano also undergoing expansion is Öræfajökull, a part of Vatnajökull, where Iceland's highest peak, Hvannadalshnjúkur is located.  Measurements confirm this expansion which is accompanied by earthquakes. The edges of the Öræfajökull crater are at an altitude of 1800 metres. This volcano has erupted twice in recorded time, the first time in 1362 and the second in 1727. The former eruption caused a lot of damage and made the farmland of Litla Hérað into a lava desert

There are two recent examples of increase in gas pressure not leading to eruption. The former was at Hrómundartindur, east of Hengill in South Iceland, not far from Reykjavik. The area underwent increased pressure between 1994- 1998 accompanied by earthquakes. Suddenly this expansion of pressure came to a halt.
The latter example was at Upptyppingar between 2007 and 2008 where pressure mounted for a year and suddenly stopped.
The recent sulphuric odours that have been detected at Jökulsá á Fjöllum, a glacial river which originates in Vatnajökull, is because of geothermal activity in Kverkfjöll when underlying hot springs are dispersing excess water, he believes.


Uncertainly level declared for Öræfajökull volcano, aviation code moved to yellow alert


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