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jgo

(979 posts)
Sat Jun 8, 2024, 09:34 AM Jun 8

On This Day: Volcanic system spews lava, gases, for 8 months causing death, famine, climate impact - June 8, 1783

(edited from Wikipedia)
"
Laki

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 and including the volcano Þórðarhyrna.

[42 billion tons of lava plus poisonous clouds]

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 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 was 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 15.5 mi long 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 the last millennium.

The eruption produced an estimated 14 km3 (18×109 cu yd) of basalt lava, and the total volume of tephra emitted was 0.91 km3 (1.2×109 cu yd). Lava fountains were estimated to have reached heights of 2,600 to 4,600 ft. The gases were carried by the convective eruption column to altitudes of about 50,000 ft.

["Laki haze" across Europe]

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 were disastrous. An estimated 20–25% of the population died in the famine after the fissure eruptions ensued. Approximately 80% of sheep, 50% of cattle and 50% of horses died because of dental fluorosis and skeletal fluorosis from the 8 million tons of fluorine that were released. The livestock deaths were primarily caused by eating the contaminated grass, while humans deaths were mostly from the subsequent famine.

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. 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, Mt. Asama erupted in Japan (Tenmei eruption). The eruption may have affected a drought in eastern China.

Consequences in Europe

An estimated 120,000,000 tonnes of sulfur dioxide was emitted, about three times the total annual European industrial output in 2006 (but delivered to higher altitudes, hence its persistence), and equivalent to six times the total 1991 Mount Pinatubo eruption. This outpouring of sulfur 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.

[Heat, and fog that disrupted shipping]

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. 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 ships stayed in port, unable to navigate, and the sun was described as "blood coloured".

[Choking death]

Inhaling sulfur dioxide gas causes victims to choke as their internal soft tissues swell – the gas reacts with the moisture in the lungs and produces sulfurous acid. The local death rate in Chartres was up by 5% during August and September, with more than 40 dead. In Great Britain, the east of England was most affected. The records show that the additional deaths were among outdoor workers; the death rate in Bedfordshire, Lincolnshire, and the east coast was perhaps two or three times the normal rate. It has been estimated that 23,000 British people died from the poisoning.

[Severe weather]

The weather became very hot, causing severe thunderstorms with large hailstones that were reported to have killed cattle, until the haze dissipated in the autumn. The winter of 1783–1784 was very severe; the naturalist Gilbert White in Selborne, Hampshire, reported 28 days of continuous frost. The extreme winter is estimated to have caused 8,000 additional deaths in the UK. During the spring thaw, Germany and Central Europe reported severe flood damage. This is considered part of a volcanic winter.

[Spread of poverty and famine]

The meteorological impact of Laki continued, contributing significantly to several years of extreme weather in Europe. In France, the sequence of extreme weather events included a failed harvest in 1785 that caused poverty for rural workers, as well as droughts, bad winters and summers. These events contributed significantly to an increase in poverty and famine that may have contributed to the French Revolution in 1789.

[Other climate sources]

Laki was only one factor in a decade of climatic disruption, as Grímsvötn was erupting from 1783 to 1785, and there may have been an unusually strong El Niño effect from 1789 to 1793.

Contemporaneous reports

Kirkjubaejarklaustur, an important church farm in South Iceland, was the home of the Rev. Jón Steingrímsson (1728–1791), who left contemporary eyewitness accounts of the effects of the eruption and its aftermath. Today, Kirkjubæjarkaustur is a small village.
Gilbert White recorded his perceptions of the event at Selborne, Hampshire, England:

The summer of the year 1783 was an amazing and portentous one, and full of horrible phaenomena; for besides the alarming meteors and tremendous thunder-storms that affrighted and distressed the different counties of this kingdom, the peculiar haze, or smokey fog, that prevailed for many weeks in this island, and in every part of Europe, and even beyond its limits, was a most extraordinary appearance, unlike anything known within the memory of man. By my journal I find that I had noticed this strange occurrence from June 23 to July 20 inclusive, during which period the wind varied to every quarter without making any alteration in the air. The sun, at noon, looked as blank as a clouded moon, and shed a rust-coloured ferruginous light on the ground, and floors of rooms; but was particularly lurid and blood-coloured at rising and setting. All the time the heat was so intense that butchers' meat could hardly be eaten on the day after it was killed; and the flies swarmed so in the lanes and hedges that they rendered the horses half frantic, and riding irksome. The country people began to look, with a superstitious awe, at the red, louring aspect of the sun; ...

"
https://en.wikipedia.org/wiki/Laki

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On This Day: Volcanic system spews lava, gases, for 8 months causing death, famine, climate impact - June 8, 1783 (Original Post) jgo Jun 8 OP
Thanks! AltairIV Jun 8 #1
You're most welcome. jgo Jun 8 #2
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