ki or Lakagígar (Craters of Laki) is a volcanic fissure in the south of Iceland, not far from the canyon of Eldgjá and the small village of Kirkjubæjarklaustur.
Lakagígar is the correct name, as Laki mountain itself did not erupt,
as fissures opened up on each side of it. Lakagígar is part of a
volcanic system centered on the volcano Grímsvötn and including the volcano Þórðarhyrna.[1][2][3] It lies between the glaciers of Mýrdalsjökull and Vatnajökull, in an area of fissures that run in a southwest to northeast direction.
The system erupted over an eight-month period between 1783 and 1784 from the Laki fissure and the adjoining volcano Grímsvötn, pouring out an estimated 14 km3 (3.4 cu mi) of basalt lava and clouds of poisonous hydrofluoric acid and sulfur dioxide compounds that killed over 50% of Iceland's livestock population, leading to a famine which then killed approximately 25% of the island's human population.[4]
The Laki eruption and its aftermath caused a drop in global temperatures, as sulfur dioxide was spewed into the Northern Hemisphere. This caused crop failures in Europe and may have caused droughts in India. The eruption has been estimated to have killed over six million people globally,[5] making it the deadliest in historical times.
The eruption, also known as the Skaftáreldar ("Skaftá fires") or Síðueldur, produced an estimated 14 km3 (3.4 cu mi) of basalt lava, and the total volume of tephra emitted was 0.91 km3 (0.2 cu mi).[8] Lava fountains were estimated to have reached heights of 800 to 1,400 m (2,600 to 4,600 ft). The gases were carried by the convective eruption column to altitudes of about 15 km (10 mi).[9]
The eruption continued until 7 February 1784, but most of the lava was ejected in the first five months. Grímsvötn volcano, from which the Laki fissure extends, was also erupting at the time, from 1783 until 1785. The outpouring of gases, including an estimated 8 million tons of hydrogen fluoride and an estimated 120 million tons of sulfur dioxide, gave rise to what has since become known as the "Laki haze" across Europe.[9]
The parish priest and dean of Vestur-Skaftafellssýsla, Jón Steingrímsson (1728–1791), grew famous because of the eldmessa ("fire sermon") that he delivered on 20 July 1783. The people of the small settlement of Kirkjubæjarklaustur were worshipping while the village was endangered by a lava stream, which ceased to flow not far from town, with the townsfolk still in church.
The summer of 1783 was the hottest on record and a rare high-pressure zone over Iceland caused the winds to blow to the south-east.[11] The poisonous cloud drifted to Bergen in Denmark–Norway, then spread to Prague in the Kingdom of Bohemia (now the Czech Republic) by 17 June, Berlin by 18 June, Paris by 20 June, Le Havre by 22 June, and Great Britain by 23 June. The fog was so thick that boats stayed in port, unable to navigate, and the sun was described as "blood coloured".[11]
Inhaling sulphur dioxide gas causes victims to choke as their internal soft tissue swells – the gas reacts
The system erupted over an eight-month period between 1783 and 1784 from the Laki fissure and the adjoining volcano Grímsvötn, pouring out an estimated 14 km3 (3.4 cu mi) of basalt lava and clouds of poisonous hydrofluoric acid and sulfur dioxide compounds that killed over 50% of Iceland's livestock population, leading to a famine which then killed approximately 25% of the island's human population.[4]
The Laki eruption and its aftermath caused a drop in global temperatures, as sulfur dioxide was spewed into the Northern Hemisphere. This caused crop failures in Europe and may have caused droughts in India. The eruption has been estimated to have killed over six million people globally,[5] making it the deadliest in historical times.
Contents
1783 eruption
On 8 June 1783, a fissure with 130 craters opened with phreatomagmatic explosions because of the groundwater interacting with the rising basalt magma. Over a few days the eruptions became less explosive, Strombolian, and later Hawaiian in character, with high rates of lava effusion. This event is rated as 6 on the Volcanic Explosivity Index, but the eight-month emission of sulfuric aerosols resulted in one of the most important climatic and socially repercussive events of the last millennium.[6][7]The eruption, also known as the Skaftáreldar ("Skaftá fires") or Síðueldur, produced an estimated 14 km3 (3.4 cu mi) of basalt lava, and the total volume of tephra emitted was 0.91 km3 (0.2 cu mi).[8] Lava fountains were estimated to have reached heights of 800 to 1,400 m (2,600 to 4,600 ft). The gases were carried by the convective eruption column to altitudes of about 15 km (10 mi).[9]
The eruption continued until 7 February 1784, but most of the lava was ejected in the first five months. Grímsvötn volcano, from which the Laki fissure extends, was also erupting at the time, from 1783 until 1785. The outpouring of gases, including an estimated 8 million tons of hydrogen fluoride and an estimated 120 million tons of sulfur dioxide, gave rise to what has since become known as the "Laki haze" across Europe.[9]
Consequences in Iceland
The consequences for Iceland, known as the "Móðuharðindin" (Mist Hardships), were catastrophic.[10] An estimated 20–25% of the population died in the famine and fluoride poisoning after the fissure eruptions ensued. Around 80% of sheep, 50% of cattle and 50% of horses died because of dental fluorosis and skeletal fluorosis from the 8 million tons of hydrogen fluoride that were released.[11][12]The parish priest and dean of Vestur-Skaftafellssýsla, Jón Steingrímsson (1728–1791), grew famous because of the eldmessa ("fire sermon") that he delivered on 20 July 1783. The people of the small settlement of Kirkjubæjarklaustur were worshipping while the village was endangered by a lava stream, which ceased to flow not far from town, with the townsfolk still in church.
- "This past week, and the two prior to it, more poison fell from the sky than words can describe: ash, volcanic hairs, rain full of sulfur and saltpeter, all of it mixed with sand. The snouts, nostrils, and feet of livestock grazing or walking on the grass turned bright yellow and raw. All water went tepid and light blue in color and gravel slides turned gray. All the earth's plants burned, withered and turned gray, one after another, as the fire increased and neared the settlements."[13]
Center of the Laki Fissure
Consequences in monsoon regions
There is evidence that the Laki eruption weakened African and Indian monsoon circulations, leading to between 1 and 3 millimetres (0.04 and 0.12 in) less daily precipitation than normal over the Sahel of Africa, resulting in, among other effects, low flow in the River Nile.[14] The resulting famine that afflicted Egypt in 1784 cost it roughly one-sixth of its population.[14][15] The eruption was also found to have affected the southern Arabian Peninsula and India.[15]Consequences in Europe
An estimated 120,000,000 long tons (120,000,000 t) of sulphur dioxide was emitted, about three times the total annual European industrial output in 2006 (but delivered to higher altitudes, hence more persistent), and equivalent to six times the total 1991 Mount Pinatubo eruption.[11][16] This outpouring of sulphur dioxide during unusual weather conditions caused a thick haze to spread across western Europe, resulting in many thousands of deaths throughout the remainder of 1783 and the winter of 1784.The summer of 1783 was the hottest on record and a rare high-pressure zone over Iceland caused the winds to blow to the south-east.[11] The poisonous cloud drifted to Bergen in Denmark–Norway, then spread to Prague in the Kingdom of Bohemia (now the Czech Republic) by 17 June, Berlin by 18 June, Paris by 20 June, Le Havre by 22 June, and Great Britain by 23 June. The fog was so thick that boats stayed in port, unable to navigate, and the sun was described as "blood coloured".[11]
Inhaling sulphur dioxide gas causes victims to choke as their internal soft tissue swells – the gas reacts
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