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Icelandic eruption: Apocalypse now? - Part 1

 

Icelandic eruption: Apocalypse now? - Part 1

Dr. Claus Rink, Geoscientist and Special correspondet
of Pattaya Mail and Chiang Mai Mail

What is happening in Iceland?

Volcanic activity in Iceland has been ongoing for weeks and is getting stronger than before.  If you are there it is like you are living on the surface of what sometimes seems like an entirely different planet, you become aware of nature’s power to assert itself over our miserably self-important affairs and to dispose of life in a few seconds.

The ash-plume on the way to Europe (picture: NASA)

The most recent eruption took place late last week.  The volcanic activity sent ash and debris 20,000 to 30,000 feet in the air and disbursed an ash cloud over northern Europe.  The ash cloud over Europe is so devastating that it has grounded air travel all over the continent and has stranded many people thousands of miles from their homes and jobs.

Scientists warn that it could be a couple of days or even weeks before the ash cloud stops posing a threat.  In addition, the volcano eruption in Iceland has also stopped many world leaders from heading to the funeral for the late Polish President who was killed in a plane crash earlier this month.

Atmosphere with ash particles

Many now fear that the March and April eruptions of the Eyjafjallajokull volcano will spawn an eruption at Katla, a much stronger volcano located in Iceland that would be expected to do massive devastation should it erupt.

Ash cloud
expanding to Russia

The ash cloud is reported to have extended near Russian air space and also throughout other areas in Europe.  Air traffic is all but grounded, and many people are having to find alternative transportation arrangements to get where they need to be.

However, the danger is that the small volcano is just the beginning and that it will trigger the far more powerful volcano of Katla, which nestles beneath Myrdalsjoekull.

Chances of
cataclysm high

Eyjafjallajökull is located west of the Katla volcano.  It is an ice-covered stratovolcano with a 2.5-km-wide summit caldera.  Fissure-fed lava flows occur on both the eastern and western flanks of the volcano, but are more prominent on the western side.  Although the 1666-m-high volcano has erupted during historical time, it has been less active than the other volcanoes of Iceland’s eastern volcanic zone, and relatively few Holocene lava flows are known.

The eruption is located on an approx. 2 km wide pass of ice-free land between Eyjaf­jallajökull and the neigh­bouring Katla volcano with its overlying Mýrdalsjökull ice cap.  Katla volcano is known for powerful subglacial phreatomagmatic eruptions producing basaltic tephra layers with volumes ranging from ~0.01 to more than 1 cubic kilometer.  This could trigger Katla, which is a vicious volcano that could cause both local and global damage.

Iceland is built on a volcanic magma chamber on the Atlantic’s mid-oceanic ridge and it has grown used to eruptions.  The southern town of Vik, close to the current eruption, is built on high ground.  They know that if Katla erupts, flooding will be sure to follow.

The island’s worst eruption in modern times was in 1783, when the Laki volcano blew its top.  The lava shot to heights of 1.4 kilometres and more than 120 million tonnes of sulphur dioxide was released into the atmosphere.  A quarter of the island’s population died and it transformed the world, creating Europes notorious “sand summer”, casting a toxic cloud over Prague, playing havoc with harvests in France - sometimes seen as a contributory factor in the French Revolution - and changing the climate so dramatically that New Jersey recorded its largest snowfall and Egypt one of its most enduring droughts.

Disaster for airlines and passengers

Millions of passengers were stranded last Friday after a huge cloud of volcanic ash from Iceland swept across Europe, grounding thousands of flights in the biggest air travel shutdown since World War II.  Europe’s air traffic control centre said 75% of the flights were cancelled because of the “unprecedented” situation and more would follow, while one airline grounded all its planes in the affected area until Monday.

Europe’s three biggest airports - London Heathrow, Paris-Charles de Gaulle and Frankfurt - were closed by the ash, leaving passengers stranded as a global flight backlog built up.  Eurocontrol, which coordinates air traffic control in 38 nations, said only 12,000 of the daily 28,000 flights in the affected zone would take off last Friday, after about 6,000 were cancelled the day before.

Glacier melt causes large floods
in Iceland

Jokulhlaups (floods of meltwater) reached the lowlands around the volcano with peak flow around noon on April 14, with destruction of roads, infrastructure, and farmlands.  There were no reported fatalities as people had been evacuated from the hazardous areas.  Tephra fall begins in southeast Iceland.  A second jokulhlaup/lahar emanates from the ice cap.

Activity continued at a similar level with ash generation and flow of meltwater in pulses.  Jokulhlaup/lahar occurred in the evening.  On April 16 some variability occurred in seismic tremor and tephra generation, but overall the eruptive activity remains stable.  The pulsating eruptive plume reached above 8 km, with overall height of 5 km.

Three large previous eruptions of Eyjafjallajökull are known in the last 1,100 years (historical time in Iceland).  The most recent began in December 1821 and lasted intermittently for more than a year.  The neighbouring volcano Katla erupted then on 26 June 1823.  Other instances include an eruption in 1612 or 1613, and about 920 A.D.

The new eruption is about ten times more powerful than the eruption before and is located under a glacier.  The glacier melted, causing glacier runs (jökulhlaup) that have twice flooded the south of Iceland.  A vast cloud of ash rose 30,000 feet into the air, endangering aircraft motors over the north Atlantic.

Katla, which is part of the same volcanic system and the current eruptions, lies under the Mýrdalsjökull glacier.  It has violently erupted before, causing sudden floods of unthinkable violence (200,000 cubic meters of water per second; the Amazon’s flow is 10,000 cubic meters per second) that wiped out roads and farms, taking people with them, and leaving the survivors on mountaintops that became islands for days at a time.

Although it has historically erupted every 40-80 years, its last major eruption was in 1918, so it is considered overdue, and there is speculation that the current activity is a precursor of a new Katla explosion.  Each of the previous three Eyjafjallajökull eruptions since Iceland’s settlement (920, 1612, and 1821-23) have been followed by a major Katla eruption.

The usual pattern with Icelandic eruptions is for rising and stretching of the surface as magma moves up to shallow depths of a few kilometres, followed by contraction and sinking of the surface as magma exits the shallow magma chamber and erupts at the surface.

From analysis of radar data scientist know of two events at Eyjafjallajökull, in 1994 and 1999, that started in a similar way with magma moving to a shallow depths (5-6 kilometres).  However, in both cases the magma then spread out laterally and remained in the crust.

At the end of the last ice age, the rate of eruption in Iceland was some 30 times higher than recent historic rates.  This is because the reduction in the ice load reduced the pressure on the mantle, leading to decompression melting there.  Since the late 19th Century the ice caps in Iceland have been shrinking yet further, due to changing climate.  This will lead to additional magma generation, so we should expect more frequent and/or more voluminous eruptions in the future.

Eyjafjallajökull is a relatively small volcano and unlikely to erupt the volumes of material that will have a significant impact on climate.  However, eruptions of Eyjafjallajökull in 1821-1823 and 1612 were followed in short shrift by eruptions of its much larger neighbour, Katla.

Geologists have no idea when it will stop.  An eruption in Iceland in 1973 lasted more than five months.

Next week in part 2 we look at the environmental changes and impacts.

Note:  Claus Rink is a geoscientist working in Iceland and Greenland and is also a teacher who gives lectures on volcanology and glaciology.  He is member of the Rotary Club Eastern Seaboard and is managing an education project for underprivileged people.