Katla rattles some more – Iceland volcano eruption draws closer

While the blogosphere has been erupting over the Wagner – Trenberth – Spencer debacle, the most dangerous volcano in iceland has been starting to rumble again, with many earthquakes in its vicinity fuelling speculation that a big eruption is on the cards.

According to website Clickgreen.org.uk the Icelandic Government has approved a series of risk assessment exercises after scientists warned of major volcanic eruptions occurring every two to seven years.

The news comes as observers report strengthening earthquakes and harmonic tremors around Katla, which signify an increasing risk of an imminent eruption.

Tonight, experts have confirmed the start of pulses of harmonic tremors, which follows 48 hours of intensifying earthquakes and tremors.

Newser.com says:

Although earthquakes around Katla are common, an increase in cluster earthquakes is not.

“It’s one of the most feared volcanos, so we’re closely monitoring it,” said Pall Einarsson of the University of Iceland. “That said, it’s normal for earthquakes to be detected around Katla. What’s a bit unusual is that we’re seeing swarms of small earthquakes, some occurring every 10 minutes or so.”

Iceland sits on a large volcanic hot spot in the Atlantic’s mid-oceanic ridge. Eruptions, common throughout Iceland’s history, are often triggered by seismic activity when the Earth’s plates move and when magma from deep underground pushes its way to the surface.

Like earthquakes, predicting the timing of volcanic eruptions is an imprecise science.

Last year’s eruption of the Eyjafjallajokull volcano forced hundreds of people to be evacuated and paralyzed international air travel for weeks because of a hovering ash cloud.

And history has shown that when Eyjafjallajokull volcano erupts, Katla _ located under the massive Myrdalsjokull icecap _ isn’t far behind.

Katla, which threatens disastrous flooding if its ice cap melts, typically awakens every 80 years or so, and last erupted in 1918.

[UPDATE 08/09]  Icelandreview.com says: 

Geophysicist Magnús Tumi Gudmundsson went on an observation flight over Mýrdalsjökull yesterday. “There is always uncertainty regarding Katla and therefore it was considered necessary to fly over the glacier to shed a light on what is going on,” he told Fréttabladid.

He noted that calderas and cracks in the glacier clearly showed increased geothermal heat and regular series of minor earthquakes also indicate that the volcano has been expanding recently.

Gudmundsson pointed out that there is only one definite indication of an onset of an eruption in Katla . “All sources on Katla eruptions over the past 500 years mention large earthquakes that can clearly be found in Mýrdalur [by Vík] a few hours before the eruption begins. That is in fact the only absolute warning.”

Seismic activity was recorded below Mýrdalsjökull yesterday but this morning it seemed to have subsided. The glacial river Múlakvísl also flooded but the water level peaked yesterday evening and the water flow has since decreased, ruv.is reports.

The calderas which caused the flood in Múlakvísl in July are unchanged but Gudmundsson said there is a new depression in the icecap to the south of them which indicate increased geothermal heat.

He added that there is no clear reason for yesterday’s earthquakes. According to ruv.is, scientists believe water may have caused the tremors, although the tremors were weaker than those that preceded the flood in Múlakvísl last summer.

Since the flood in July approximately 800 minor earthquakes have been registered in the area, compared to 300 last year. Gudmundsson iterated there is good reason to be prepared for an eruption but these series of events won’t necessarily lead to one.