[BREAKING] Vulkanen IJsland #21: Eruptie op komst bij Reykjanes?

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A series of tremors hit the Tungnafellsjökull glacier in the Icelandic highlands this morning.

A total of eleven tremors over magnitude 2 were felt in the area this morning, with the strongest – a magnitude 2.9 – coming around 11am.

According to Hildur María Friðriksdóttir from the Icelandic Met Office, tremor waves of this kind are common in the area and are no cause for concern.

Tungnafellsjökull is a relatively small (10 x 5km) glacier to the north-west of the mighty Vatnajökull glacier in South Iceland.

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Bárðarbunga Volcano Might Erupt Again

Geologists are now investigating data, indicating that magma might be accumulating again under Bárðarbunga volcano in Vatnajökull glacier. The Holuhraun eruption, which took place between August 31, 2014, and February 27, 2015, was part of a series of events which started in the volcano in 1974 and might provide evidence about the behavior of the volcano in the future.

According to Páll Einarsson, professor of geophysics at the University of Iceland, the next few months will determine whether magma is in fact accumulating. “That’s the big question,” he told RÚV. “There are some indications that this might be the case, but we have to investigate it further.”

The signals, gathered by new equipment on location, are not clear and come from a great depth. Geologists are still learning how to interpret such data.

The Holuhraun eruption is now seen as a chapter in a story that began in 1974. That year, a series of large earthquakes began, which hit at regular intervals in Bárðarbunga. The first chapter ended 22 years later with the eruption and glacial flood in Gjálp in 1996.

After the Gjálp eruption, the volcano was silent for many years, but a few years ago, a new series of earthquakes began, culminating in the Holuhraun eruption in the northeastern highlands in August 2014. The magma came from Bárðarbunga and the caldera sank by 60 meters (197 feet) in the course of the eruption.

Páll believes it’s possible that the next eruption might occur in Bárðarbunga itself. “Bárðarbunga is probably the most powerful volcano in Iceland … Bárðarbunga is the center of a volcanic system which often erupts at the periphery, but still more frequently in the volcano itself.”

It is difficult to predict when the next eruption might start and whether previous eruptions can be used as evidence as to what might happen next. Páll concludes: “We have 30 volcanic systems in Iceland and each one of them has its own personality. To predict what is likely to happen in the near future we have to get to know them a bit personally.”

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Katla hit by series of tremors
A 3.3 magnitude tremor hit the south-east of Katla, one of Iceland’s most active volcanoes, in the early hours of this morning.

The main tremor was followed by around ten aftershocks, some of which were shallow and possibly connected to geothermal activity, the Icelandic Met Office reports.

No significant changes to nearby rivers have been reported, but the relevant data will be studied more closely.

“Katla sees this type of seismic cycle from time to time – on average 1-3 times a year,” says the Met Office. “We are monitoring the area closely and will keep everybody informed of any changes. At the moment, things appear to have quietened down.”

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Earthquake activity in Bárðarbunga and Grímsfjall volcanoes

Yesterday (17-March-2016) an earthquake swarm took place in Bárðarbunga volcano. This is a weekly cycle at the moment in Bárðarbunga volcano so older readers are used to seeing and read about it already. This started in September 2015 (for the new readers) after the eruption in Holuhraun ended in February 2015. This activity suggest that magma has started to flow into the magma chamber in Bárðarbunga volcano again at faster speeds than before the eruption in Holuhraun. The exact rate is difficult to know, since the magma that started the eruption in Holhraun had been building up in Bárðarbunga volcano since 1970-ish and part of that time earthquake recording was poor or did not exist in Iceland or parts of it until 1995 when the SIL network was created by Veðurstofa Íslands.

The largest earthquake this week had the magnitude of 3,4 while other earthquakes that took place had smaller magnitude. The second largest earthquake had the magnitude of 2,8. Other earthquakes where smaller in magnitude. It is also interesting that part of the earthquake swarm aligned it self along north-south fault in the eastern part of the caldera. That is a new feature, either a weakness is forming at this location or something else is up. This area has around 300 – 500 meter thick glacier on top of it and an eruption at this location would be extremely bad. The glacier flood from eruption at this location would mostly go down Jökulsá á fjöllum glacier river. Other flood locations can’t be ruled out (I’m not an expert on glacier floods and I do have limited knowledge of the landscape under the glacier).

Grímsfjall volcano

It has been five years since Grímsfjall volcano erupted in a largest eruption in 140 years for Grímsfjall volcano. Over the past few weeks there has been a slight increase in earthquake in Grímsfjall volcano. At the moment this doesn’t mean an eruption is imminent, the thing however about eruptions in Grímsfjall volcano is that they happen suddenly and without warning. Normally eruption happens in Grímsfjall volcano every 3 – 5 years on average, sometimes its shorter and sometimes its longer between eruptions.

Notice on Böðvarshólar geophone station

For the longest time now I’ve been having 3G connection issues with Böðvarshólar geophone station. The problems include poor signal, little bandwidth. The poor signal leaks into my recording of earthquakes, making them bad and extremely noisy and that makes them less usable for me. I am going to attempt to improve this situation but if that fails I will have to turn the station down. Since the cost of getting a good antenna for this location is too high and the solution takes too long to implement anyway. I will post a notice if I take down the Böðvarshólar geophone station. If it happens, it is going to happen before I move to Denmark.

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Op zaterdag 19 maart 2016 14:56 schreef DemonRage het volgende:
Gaan we weer zo'n periode krijgen dat we met z'n allen met spanning de IJslandse vulkanen in de gaten gaan houden?

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Earthquake Hits Major Volcano Site

There was a major earthquake on the northern edge of the Bárðarbunga volcanic craters at around midnight last night.

The quake measured 4.2 on the Richter scale and is therefore the largest quake to have hit the famous volcano since it stopped erupting in February last year.

According to Bjarki Fries, a naural disasters specialist with the Icelandic met office, the earthquake emanated from 3.5 kilometers underground. Around 15 aftershocks have already been measured, the most powerful of which was a 3.5 quake at 01.00 this morning.

Met office earthquakes specialist Martin Hensch told RÚV that there is no evidence of lava movements or of any eruption activity connected to the earthquakes, but that the situation will be monitored carefully. There were two quakes in the same location on April 3, measuring 3.4 and 3 on the Richter scale.

The recent eruption at Bárðarbunga, often known as Holuhraun, lasted from late August 2014 to late February 2015, and despite not affecting aviation or physically threatening any human settlements, it caused dangerous levels of pollution around Iceland and produced more new lava than almost any other eruption in Iceland since the Vikings first arrived.

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Op dinsdag 21 juni 2016 22:06 schreef aloa het volgende:
Hekla staat op uitbarsten...

http://www.hln.be/hln/nl/(...)zen-grote-ramp.dhtml

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Is Hekla really going to blow?
The volcanoes of Iceland are some of the most closely watched on the planet. Not only is there an extensive seismic array that records all the earthquakes that occur on the island nation, but many volcanoes have both GPS monitoring of their shape and borehole strain gauges that measure stresses underground caused by these changes in shape. There have been examples in Iceland where sudden and strong changes in strain in these boreholes came right before an eruption, including the 2000 eruption of Hekla. Volcanologists in Iceland are watching for any signs that an eruption might be in the works so that appropriate measures to protect lives and property can be enacted.

That’s why it is a little peculiar that Dr. Páll Einarsson of the University of Iceland warned people and airplanes to “stay away” from Iceland’s Hekla based on his interpretation of accumulated strain at the volcano. According to reports coming out of Iceland, Dr. Einarsson says that strain measured on these strain gauges is higher than it was prior to the 2000 eruption. Also, it has been 16 years since Hekla’s last eruption and, at least for a brief period from 1970-2000 (mind you, this is a very short time for the lifespan of any volcano), it was erupting about every 10 years. Put those together and he thinks that Hekla is ready for its next eruption, and it could happen soon.

However, I am a little perplexed by this statement from Dr. Einarsson and I wish I knew more about the context in which the quotes were given. Without confirmation from the Icelandic Met Office (the volcano monitoring agency), I don’t really know how to assess the validity of what Dr. Einarsson is saying.

Volcanoes care not for your puny human schedules, so you might expect an eruption soon ... or might not.

Does this mean that doom is coming? Not necessarily. As I said, although Hekla did have a pattern of eruptions every ten years after 1970, prior to that the volcano had no eruption from 1947 to 1970, over 22 years. In fact, if you go back to the 1597 AD eruption (again, be wary of any arbitrary starting point for statistics), Hekla has had eight eruptions separated by anywhere from 32 to 79 years (and if I wanted to choose the most common repose interval, it is ~35 years). That being said, volcanoes care not for your puny human schedules, so you might expect an eruption soon … or might not.

Scientists also don’t have strain data going back further than the 2000 eruption of Hekla, so they don’t have a good baseline for understanding exactly how the strain changes before every eruption—just what happened prior to the 2000 event. That’s not to say that they shouldn’t expect something similar, but the data is somewhat scant.

You can actually see the near real-time strain data coming from around Hekla. Now, I am no expert on these readings, but if you compare them to the readings before the 2000 eruption, there doesn’t seem to be much sign of an eruption coming in the near future (that is, next few hours to days). The five gauges are all roughly the same and prior to the 2000 eruption, they all diverged as the new magma intruded the volcano. You can also check out the earthquakes recorded near Hekla and nothing suspicious appears to be happening either.

For an Icelandic volcano, Hekla has a surprisingly explosive history of eruptions. These explosive eruptions have produced ash plumes that reached over 15 kilometers (~50,000 feet). They are also eruptions that tend to be rich in fluorine, which is especially hazardous to grazing animals as they eat fluorine-contaminated ground cover that leads to fluorinosis (and many times, death). You can imagine the travel ramifications of a large explosive eruption from Hekla—we saw that during the 2010 eruption of Eyjafjallajökull. Hekla has produced some large fissure eruptions as well, with abundant basaltic lava flows, much like what we saw from the Holuhraun eruption in 2014-15.

Now, I’m not saying that Dr. Einarsson is wrong to be point out what he thinks the threat of Hekla right now might be, but without official world from the IMO or emergency management agencies in Iceland, I worry that these statements could be jumping the gun (if Dr. Einarsson was quoted correctly). One of the biggest challenges for volcano monitoring and mitigation is getting people to believe the threat when it presents itself. Too many false alarms, even if they aren’t coming from the official monitoring and management agencies, can make people feel like they can’t trust officials (see: L’Aquila earthquake in Italy). I hope that the IMO releases a statement soon in response to what Dr. Einarsson said so we can know what might be happening at Hekla. Until then, you can watch Hekla on its webcam.