Dr. Claus Rink, Geoscientist and Special correspondet
of Pattaya Mail and Chiang Mai Mail
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.
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.
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
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.
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
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
Next week in part 2 we
look at the environmental changes and impacts.
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