Laki Was History’s Deadliest Volcano
The Laki eruption in 1783 was not one of history’s most powerful volcanic events. It was not a violent and massive explosion like Krakatoa or Tambora or Vesuvius. It did not go off with a thunderous 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 explosion. Instead, it was 8 months of rumblings. There were some small eruptions every now and then, with lava slowly seeping out, while the volcano steadily spewed sulfuric dioxide gasses. In short, Laki was not a vigorous and energetic volcano, but a tired and lazy one, farting gasses for 8 months before it finally subsided. Nonetheless, Laki was the deadliest volcanic eruption in human history.
Its deadliness was a result of its steady release, during its 8 months of activity, of massive amounts of gasses. They included flourine, and over 120 million tons of sulfuric dioxides, which produced fog and haze as far away as Syria. The flourine settled on Iceland’s grass, which gave grazing animals flouride poisoning and killed most of the island’s livestock. Because of the loss of livestock, about a quarter of Iceland’s human population starved to death.
However, Iceland was thinly populated, so the death of a quarter of its inhabitants did not make Laki history’s deadliest eruption. The greatest impact lay beyond Iceland, where Laki’s eruption led to a decline in temperatures throughout the northern hemisphere. Winter temperatures in the US, for example, dropped 10 degrees Fahrenheit in 1783, and remained below normal for several years afterwards. Still, Laki’s deadliest impact was not in the US or North America.
The worst effects were felt in Europe and those parts of the northern hemisphere, southeast of Iceland. The summer of 1783 had been a particularly hot one, and a rare high pressure zone formed over Iceland, which caused winds to blow to the southeast. So when Laki started spewing prodigious amounts of sulfuric dioxide gasses into the sky, they were carried by the winds from Iceland in a southeasterly direction. There, they caused crop failures in Europe, draught in North Africa and India, Japan’s worst famine, as well as a historic famine in Egypt, where a sixth of the population starved to death in 1784. The Laki eruption and its aftermath caused the deaths of an estimated six million people. That made it the deadliest eruption in human history. It also illustrated that low energy but large volume eruptions over an extended period can have a greater impact than huge explosive eruptions.