1783 Laki Eruption
The Laki eruption of 1783 was not one of history’s most powerful volcanic events – it was not a massive and violent eruption like Vesuvius or Krakatoa or Tambora, or what most people imagine when picturing a volcano going off with a bang, blowing its top, and releasing a massive amount of energy in a dramatic explosion with fires reaching to the heavens and rivers of lava rushing down the volcano’s sides.
Indeed, the Laki eruption was not even a single explosive event, but rather 8 months of rumblings, interspersed by relatively small eruptions from time to time, with lava slowly seeping out of the side every now and then, while the volcano steadily spewed sulfuric dioxide gasses. Laki was not a vigorous and energetic volcano, but a tired and lazy one, steadily farting gasses for 8 months before it finally subsided and went quiet. Nonetheless, Laki was the deadliest volcanic eruption in human history.
Its deadliness was a result of its steady release, during its 8 months of rumbling and periodic small explosions, of massive amounts of gasses, including fluorine and over 120 million tons of sundry sulfuric dioxides, which produced fog and haze as far away as Syria. The fluorine settled on Iceland’s grass, which gave grazing animals fluoride poisoning and killed most of the island’s livestock. The loss of livestock, in turn, caused a quarter of Iceland’s human population to starve to death.
But Iceland was and remains sparsely populated, so the death of a quarter of its population did not make Laki history’s deadliest eruption. Beyond Iceland, the eruption led to a decline in temperatures in the northern hemisphere – winter temperatures in the US, for example, dropped 10 degrees Fahrenheit in 1783, and remained below normal for several years afterward. Laki’s deadliest impact was not in the US or North America, however.
The deadly impact was in Europe and the northern hemisphere to the southeast of Iceland. The summer of 1783 had been a particularly hot one, and a rare high-pressure zone formed over Iceland that year, which caused winds to blow to the southeast. Thus, when Laki began spewing prodigious amounts of sulfuric dioxide into the sky, they were carried by the winds from Iceland in a southeasterly direction, where they caused crop failures in Europe, draught in North Africa and India, Japan’s worst famine, as well as a historic famine in Egypt, a sixth of whose population starved to death in 1784.
It is estimated that the Laki eruption and its aftermath caused the deaths of an estimated six million people, making it the deadliest volcanic eruption in human history, and illustrating that low energy but large volume eruptions over an extended period can have a greater impact than massive explosive eruptions.