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Geologists working near the Holuhraun eruption north of Vatnajokull have been advised to leave, as increased volcanic tremor has been detected in the vicinity. GPS measurements show that the magma intrusion has increased since the beginning of the current eruption and a rift valley has formed.
notice how earthquake activity decreases during daylight hours, only since the eruption though on the 29th,
wonder why that is?
"Geologists working near the Holuhraun eruption north of Vatnajokull have been called back, as increased volcanic tremor has been detected in the vicinity. GPS measurements show that the magma intrusion has increased since the beginning of the current eruption and a rift valley has formed."
"Our GPS measurements of land deformation show that the intrusion has gotten wider," says Dr. Einarsson. "That´s why this Graben, or small rift valley has formed; the intrusion is simply getting more material than it is releasing throught the Holuhraun eruption, and this is a cause for concern, because it increases the likelyhood of something else happening."
The current eruption is an effusive lava eruption on barren land, with little or no explosive activity and no ash production. "This was the best possible scenario for an event of this nature," says Dr. Einarsson. "But the Holuhraun eruption is in effect not large enough, to act as a safety valve for the intrusion; it´s still gettting wider, and magma from it could breach the surface in other places. This causes concern, because other scenarios, among them a subglacial eruption, are possible."
The scientist at ISOR say it is impossible to predict how long the eruption at Holuhraun will last. That depends mainly on how clean a path the magma will have, from the source at Bardarbunga, to the eruption site. The Krafla Fires (an eruption in the Krafla volcanic system in the north of Iceland in the 1970s and 80s) came in short bursts, with the magma gathering steadily in a shallow magma chamber, and flowing from there intermittently into the fissure system.
The lava flowing from the fissure north of Vatnajokull is classified as Pahoehoe lava - a type of basaltic lava that is very common in eruptions in Iceland. The term comes from Hawaii and means smooth unbroken lava. The lava at Holuhraun is so thin however, that it forms slabs on the surface.
Warning of flooding in the area. Rögnvaldur Olafsson, a project manager with Civil Protection, said of crisis yet the level of risk, has not been considered necessary to move the capabilities neyðarstig so far. He says the reason for the spaces Gunni unrest in the region. "It is out of this increased volatility as shown in meters, because it can not locate it exactly and you can not say that it relates directly eruption is in progress, or at least not visible and can not quite known what is going on, "says Tries. "It's jarðsig running out and extends beneath it, so this is part of a larger context."
Following the eruption of Eyjafjallajökull in 2010, it was emerged and supplemented by data collected during the period of cool, Iceland and obviously against all odds, slid not to Europe, but it follows the movement of the North American plate. So the main consequence is that the hot spot is therefore no longer at the center of the island, but appears more easterly thereof.
Prof Páll Einarsson, geophysicist at the University of Iceland, commented: "It is already clear that the event presently in progress is a significant magmatic and tectonic event. In terms of seismicity, volumes, and displacements involved only two events in recent decades are comparable to this one. These are the Gjálp eruption in the Bárðarbunga area in 1996 and the Krafla rifting episode of 1975-1989. The presently propagating dike is superseded by only the initial dyke in the Krafla sequence of dykes. In fact, is resembles that event in many ways. The possibility must be seriously considered that we are witnessing the initial phase of a major rifting episode on the scale of the Krafla episode and the similar episode that began in Afar in 2005."
Ármann says if Fissure will cover the glacier area will be very dangerous. There is no one who does a longer than five minutes from the car - people have short time begins to erupt under ice.
Model calculations based on continuous GPS measurements north of Vatnajökull since midnight August 31 to the end of the day September 2 , indicate an increased volume of magma insert ( passing under Dyngjujökli and vent ) . In addition, the article observed fissures in the northern Rift Dyngjujökli and radar images from yesterday ( see photo below of the page ) for the divergence of the region. Thus it can not be ruled out that gosprungan may be extended in both directions. It is therefore appropriate that all who are in the area take care of both scientists and others.
"An increased tremor was a cause for concern, because we did not see increased activity in the eruption itself," says Dr. Hoskuldsson. "If magma had breached the surface under the Dyngjujokull glacier, we would not see it until either the eruption had melted through the glacier, or when the meltwater had started to flood from beneath the margin of the glacier. So the only sensible option was to clear the area immediately."
The magma intrusion which feeds the Holuhraun eruption comes from the south, from the Bardarbunga volcano. Most of the intrusion lies deep beneath the Vatnajokull glacier and Dyngjujokull outlet glacier, so a subglacial eruption is a very real possibility, says Dr. Hoskuldsson. "We know where the magma is coming from, and in episodes like this, experience has shown that eruptions can occur near the source. Given that the current eruption is quite near the edge of the glacier, we would expect a subglacial eruption."