Laki (Icelandic pronunciation: [ˈlaːcɪ] ) or Lakagígar ([ˈlaːkaˌciːɣar̥], Craters of Laki) is a volcanic fissure in the western part of Vatnajökull National Park, Iceland, not far from the volcanic fissure of Eldgjá and the small village of Kirkjubæjarklaustur. The fissure is properly referred to as Lakagígar, while Laki is a mountain that the fissure bisects. Lakagígar is part of a volcanic system centered on the volcano Grímsvötn, including the volcano Þórðarhyrna. 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 violently over an eight-month period between June 1783 and February 1784 from the Laki fissure and the adjoining volcano Grímsvötn. It poured out an estimated 42 billion tonnes or 14 km3 (18×10^9 cu yd) of basalt lava, as well as clouds of poisonous hydrofluoric acid and sulfur dioxide compounds that contaminated the soil, leading to the death of over 50% of Iceland's livestock population and the destruction of the vast majority of all crops. This led to a famine, which then killed at least a fifth of the island's human population, although some have claimed a quarter. The Laki eruption and its aftermath caused a drop in global temperatures, as 120 million tonnes of sulfur dioxide were spewed into the Northern Hemisphere. This caused crop failures in Europe and may have caused droughts in North Africa and India.
1783 eruption
On 8 June 1783, a 25 km-long (15.5 mi) fissure of at least 130 vents 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 4 on the volcanic explosivity index, but the eight-month emission of sulfuric aerosols resulted in one of the most important climatic and socially significant natural events of that millennium. The eruption, also known as the Skaftáreldar [ˈskaftˌauːrˌɛltar̥] ("Skaftá fires") or Síðueldur [ˈsiːðʏˌɛltʏr̥] produced an estimated 14 km3 (18×10^9 cu yd) of basalt lava, and the total volume of tephra emitted was 0.91 km3 (1.2×10^9 cu yd). 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 around 15 km (50,000 ft). The eruption continued until 7 February 1784, but most of the lava was ejected in the first five months. One study states that the event "occurred as ten pulses of activity, each starting with a short-lived explosive phase followed by a long-lived period of fire-fountaining". Grímsvötn volcano, from which the Laki fissure extends, also erupted at the time, from 1783 until 1785. The outpouring of gases, including an estimated 8 million tonnes of fluorine and an estimated 120 million tonnes of sulfur dioxide, gave rise to what has since become known as the "Laki haze" across Europe.
Consequences in Iceland The consequences for Iceland, known as the Móðuharðindin [ˈmouːðʏˌharðɪntɪn] (mist hardships), were disastrous. An estimated 20% of the population died in the famine after the fissure eruptions ensued, with about 8,000 excess deaths. About 80% of sheep (190,500 head), 50% of cattle (11,500 head), and 50% of horses (28,000 head) died because of dental and skeletal fluorosis from the 8 million tons of fluorine that were released. Milk yields halved. The livestock deaths were primarily caused by eating contaminated grass, while the humans' deaths were from the subsequent famine, not fluorine poisoning. The parish minister and provost of Vestur-Skaftafellssýsla, Jón Steingrímsson (1728–1791), grew famous for the eldmessa [ˈɛltˌmɛsːa] ("fire mass") that he delivered on 20 July 1783. The church farm of Kirkjubæjarklaustur was endangered by a branch of the lava flow that halted not far from the farm, while the Rev. Jón and his parishioners were worshipping in the church. The spot at which the lava diverted away from the church became known thereafter as Eldmessutangi [ˈɛltˌmɛsːʏˌtʰauɲcɪ] ("Fire Mass Point").
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 grey. All the earth's plants burned, withered, and turned grey, one after another, as the fire increased and neared the settlements.
Consequences in monsoon regions Some evidence indicates 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. The resulting famine that afflicted Egypt in 1784 cost it roughly one-sixth of its population. The eruption was also found to have affected South Arabia and the already ongoing Chalisa famine in India.
Consequences in East Asia The Great Tenmei famine of 1782–1788 in Japan may have been worsened by the Laki eruption. In the same year, Mount Asama erupted in Japan (Tenmei eruption). The eruption may have affected a drought in eastern China.
Consequences in Europe
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