Laki Eruption in 1783
Sunday, 11. February 2007, 11:07:38
The Laki volcano eruption on Iceland in 1783 lasted eight months during which time about 14 cubic km of basaltic lava and some tephra were erupted from a 25-km-long fissure. Haze from the eruption was reported from Iceland to Syria. In Iceland, the haze lead to the loss of most of the island's livestock (by eating fluorine contaminated grass), crop failure (by acid rain), and the death of one-quarter of the human residents (by famine).
It is estimated that 80 Mt of sulfuric acid aerosol was released by the eruption (80 times more than Mount St. Helens). The poison gas cloud killed 30,000 Britons - and it could happen again! In the United Kingdom, the summer of 1783 was known as the "sand-summer" due to ash fallout. We should heed the lessons, experts warn! Tens of thousands of people in the UK face the threat of being poisoned by lethal gas - from volcanoes 1000 km away in Iceland.
People died in such vast numbers because the volcanic cloud exacerbated their respiratory illnesses. According to new research, most victims in Britain died from heart and lung problems caused by the gas and fine dust from the cloud and from associated hot climatic conditions causing additional health problems. A similar eruption today would kill up to 100,000 people in the UK because it now has a much larger population and a much bigger percentage of it is elderly and therefore more vulnerable.
Iceland has the world's highest number of so-called fissure volcanoes, a particularly dangerous type because of the vast quantities of atmospheric pollution they can produce. Unlike ordinary volcanoes, these erupt when vast cracks, sometimes up to 60 km long, open up in the ground. Icelandic fissure volcanoes can erupt continuously for more than five years. Fissure volcanoes don't erupt as explosively as ordinary volcanoes, so gas and ash aren't thrown up into the upper atmosphere but circulate instead lower down, causing severe air pollution over a very wide area. Winds determine the direction in which the pollution goes (see map of ash fall direction).
Apart from causing widespread respiratory problems, the volcanic cloud of 1783 hit Britain in other ways too. Initially it helped to raise temperatures and severely damaged vegetation, including crops. After several months of continuous eruption, sulphur levels in the atmosphere reduced the amount of solar heat reaching the surface and temperatures fell alarmingly.
A further 200,000 people died in France, the Low Countries and northern Italy. In the eastern United States, the winter average temperature was 4.8 degrees C below the 225 year average. There is also evidence that the Laki eruption had effects beyond Europe and America, with weakened African and Indian monsoon circulations, leading to precipitation anomalies of -1 to -3 mm per day over the Sahel of Africa, resulting in, amongst other effects, low flow in the River Nile.
See also my log on fissure volcanoes.
It is estimated that 80 Mt of sulfuric acid aerosol was released by the eruption (80 times more than Mount St. Helens). The poison gas cloud killed 30,000 Britons - and it could happen again! In the United Kingdom, the summer of 1783 was known as the "sand-summer" due to ash fallout. We should heed the lessons, experts warn! Tens of thousands of people in the UK face the threat of being poisoned by lethal gas - from volcanoes 1000 km away in Iceland.
People died in such vast numbers because the volcanic cloud exacerbated their respiratory illnesses. According to new research, most victims in Britain died from heart and lung problems caused by the gas and fine dust from the cloud and from associated hot climatic conditions causing additional health problems. A similar eruption today would kill up to 100,000 people in the UK because it now has a much larger population and a much bigger percentage of it is elderly and therefore more vulnerable.
Iceland has the world's highest number of so-called fissure volcanoes, a particularly dangerous type because of the vast quantities of atmospheric pollution they can produce. Unlike ordinary volcanoes, these erupt when vast cracks, sometimes up to 60 km long, open up in the ground. Icelandic fissure volcanoes can erupt continuously for more than five years. Fissure volcanoes don't erupt as explosively as ordinary volcanoes, so gas and ash aren't thrown up into the upper atmosphere but circulate instead lower down, causing severe air pollution over a very wide area. Winds determine the direction in which the pollution goes (see map of ash fall direction).Apart from causing widespread respiratory problems, the volcanic cloud of 1783 hit Britain in other ways too. Initially it helped to raise temperatures and severely damaged vegetation, including crops. After several months of continuous eruption, sulphur levels in the atmosphere reduced the amount of solar heat reaching the surface and temperatures fell alarmingly.
A further 200,000 people died in France, the Low Countries and northern Italy. In the eastern United States, the winter average temperature was 4.8 degrees C below the 225 year average. There is also evidence that the Laki eruption had effects beyond Europe and America, with weakened African and Indian monsoon circulations, leading to precipitation anomalies of -1 to -3 mm per day over the Sahel of Africa, resulting in, amongst other effects, low flow in the River Nile.
- The Independent of 14 January 2007 at http://news.independent.co.uk/environment/article2152450.ece
- Energy Balance (Blog) at http://ergobalance.blogspot.com/2007/01/uk-poison-gas-cloud-30000-people-killed.html
- Nasa: Historic Volcanic Eruption Shrunk the Mighty Nile River at http://www.nasa.gov/centers/goddard/news/topstory/2006/volcano_nile.html
See also my log on fissure volcanoes.
You must be logged in to write a comment. if you're not a registered member, please 
