Monday, August 18, 2014

Iceland: Watching Bárðarbunga

image

Credit Icelandic Met Office

 

# 8967

 

Over the past 48 hours more than 1,000 (mostly small) earthquakes have been recorded very near Iceland’s largest active volcano and the Icelandic Met Office has raised the aviation alert status for Bárðarbunga  to Orange.   While an eruption is by no means certain, Bárðarbunga has an impressive geologic history, making this swarm worth keeping an eye on.

 

image

 

First the latest update from the Icelandic Met Office, then I’ll be back with a bit more.

 

  • Note

    Intense earthquake swarm continues at Barðarbunga. Presently there are no signs of magma moving to the surface.

Bárðarbunga, Vatnajökull ice-cap, in 1996.


Seismic activity at Bárðarbunga persists

18.8.2014

The intense seismic activity that started on 16 of August at Bárðarbunga persists. Very strong indications of ongoing magma movement, in connection with dyke intrusion, is corroborated by GPS measurements. There are currently two swarms: one to the E of Bárðarbunga caldera and one at the edge of Dyngjujökull just E of Kistufell. At 2.37 am on the 18th a strong earthquake (M4) was located in the Kistufell swarm.

This is the strongest earthquake measured in the region since 1996. As evidence of magma movement shallower than 10 km implies increased potential of a volcanic eruption, the Bárðarbunga aviation color code has been changed to orange. Presently there are no signs of eruption, but it cannot be excluded that the current activity will result in an explosive subglacial eruption, leading to an outburst flood (jökulhlaup) and ash emission. The situation is monitored closely.

 

You can read earlier dispatches going back 2 days from the Icelandic Met office at these links:

Activity in Bárðarbunga volcano

Earthquake swarm by Bárðarbunga volcano

 


There is no way of knowing at this time whether Bárðarbunga will erupt, or if it does, how big of an impact it would have.  A major eruption, while possible, is not necessarily the most likely scenario.

 

Roughly 8500 years ago this system did spew forth one of the largest known lava flows of the Holocene (present) era. But the volcano is located in a remote area - far from any large cities - and its biggest threat today may well be from floods due to melting of its thick glacial cap.

 

But we do know that occasionally Icelandic volcanoes have produced significant disruptions – not only locally – but also on a more international scale.

 

In the spring of 2010, the relatively small eruption of Iceland’s Eyjafjallajökull volcano sent thick plumes of ash into the atmosphere, closing many air corridors in Europe and disrupting travel for 6 days, illustrating just how vulnerable our modern world still remains to geologic events.  

 

An estimated 100,000 flights were affected, at a cost of over 1.7 billion dollars.  That said, not every volcanic eruption produces large ash plumes. 

 

In response to the impact of  Eyjafjallajökull  the UK’s National Risk Register For Civil Emergencies – essentially a short list of disaster scenarios (man-made & natural) that the Cabinet Office believe to be genuine threats – added volcanic eruptions in 2013. 

 

This despite the fact that there are no active volcanoes in the UK or Ireland.

 

Their concern stems from the impact of volcanic eruptions outside of their country – most notably, in Iceland. Specifically they cite:

 

Severe effusive (gas-rich) volcanic eruptions abroad – The 2010 eruption of the Eyjafjallajökull volcano in Iceland showed some of the consequences that a volcanic eruption abroad can have on the UK and its citizens. Following consultation with geological and meteorological experts about the potential risks the UK faces from volcanic eruptions in Iceland or elsewhere, the assessment is that there are two main kinds of risk from volcanic eruptions.

The first is an ash-emitting eruption, similar to that in 2010.

The second, which is slightly less likely than an ash-emitting eruption, but which could have widespread impacts on health, agriculture and transport, is an effusive-style eruption on the scale of the 1783–84 Laki eruption in Iceland. This second type of eruption is now one of the highest priority risks in the NRA and the NRR.

 

For those not familiar with the 1783 event –in that year the Craters of Laki in Iceland erupted and over the next 8 months spewed immense clouds of clouds of deadly hydrofluoric acid & sulphur dioxide, killing over half of Iceland’s livestock and roughly 25% of their population.

 

These noxious clouds drifted over Europe, and resulted in widespread crop failures and thousands of deaths from direct exposure to these fumes. There are also anecdotal reports that suggest this eruption had short-term global climate impacts as well.

 

Another eruption of the type and scale seen in 1783 could present an enormous disaster scenario not only to the UK, but to all of Europe.  Earlier this summer the British Geological Survey produced a 123 page volcanic risk report called LARGE‐MAGNITUDE FISSURE ERUPTIONS IN ICELAND: SOURCE CHARACTERISATION outlining the possible risks and uncertainties.

 

While volcanic eruptions are normally a localized (albeit often destructive and traumatic) event, sometimes they can have global impact.  

 

  • When Mount Pinatubo erupted in the Philippines in 1991, within a year its aerosol cloud had dispersed around the globe, resulting in `an overall cooling of perhaps as large as -0.4°C over large parts of the Earth in 1992-93’ (see USGS The Atmospheric Impact of the 1991 Mount Pinatubo Eruption).
  • Similarly, the explosion of Mount Tambora on the island of Sumbawa, Indonesia in 1815 killed an estimated 90,000 people locally, but its impact was felt around the globe as its ash & gas lowered temperatures across much of the Northern Hemisphere in 1816, contributing to crop failures, weather disruptions, and famine in parts of North America, Europe, and Asia.

 

None of this is to suggest that the recent activity at Bárðarbunga portends a major eruption, or that it poses a significant threat beyond Iceland.  As we saw with Mt. Hekla a little over a year ago, these threats often subside without incident or turn out far less disruptive than originally feared.

 

But we live on a turbulent and geologically active planet, orbiting a variable star, in an area of space littered with rocks and debris.

 

Earthquakes, volcanoes, Solar Flares, tsunamis, violent storms, even incoming space rocks (see Russia: Hundreds Injured By Meteorite Strike) – while relatively rare – do happen.  And often without warning.

 

While most will have limited impact, you just never know which one will touch you and your loved ones.

 

Which is why FEMA and Ready.gov (along with many other state and federal agencies) urge personal, family, business, and community preparedness for all types of natural or man-made disasters, and why this blog will be focusing on preparedness issues during National Preparedness Month (September).

No comments: