Ash, Fire and Cooling Skies: Eight Eruptions from Vesuvius to Kilauea

The path opens on 24 August 79, when Vesuvius sent a column of tephra and gas about 33 kilometers up and buried Pompeii and Herculaneum under pyroclastic surges and ash. It is a Volcanic Explosivity Index 5 event, and it is unusual because two eyewitness letters from Pliny the Younger describe it. The remains of over 1,500 people have been found, but the total death toll is unknown.

Samalas on Lombok erupted in 1257 with a probable Volcanic Explosivity Index of 7, one of the largest eruptions of the Holocene. Pyroclastic flows buried much of Lombok and crossed the sea to Sumbawa, and the city of Pamatan was destroyed. Its sulfate aerosols are tied to a volcanic winter and famines abroad, while any link to the Little Ice Age remains debated.

Laki in Iceland erupted for eight months from June 1783, pouring out about 14 cubic kilometers of basalt lava along with hydrofluoric acid and sulfur dioxide. Here the killer was gas, not blast: over half of Iceland's livestock died, crops failed, and a sulfurous haze spread over Europe. It rates only Volcanic Explosivity Index 4, which shows that size on that scale does not measure harm.

Tambora on Sumbawa, in April 1815, is rated 7 on the Volcanic Explosivity Index and counts as the most powerful eruption in recorded history. About 10,000 to 11,000 people were killed directly, and its ash veil cooled global temperatures by about half a degree Celsius. The result was the Year Without a Summer of 1816, with June frosts in New England and failed harvests across Europe.

On 8 May 1902 a pyroclastic surge from Mount Pelée swept through Saint-Pierre, Martinique, at hurricane speed, and about 28,000 people died within minutes. The overall toll of roughly 29,000 makes it the deadliest eruption of the 20th century. It also gave volcanology the term Peleean eruption, though at Volcanic Explosivity Index 4 it was far smaller than Tambora.

Nevado del Ruiz in Colombia erupted on 13 November 1985 after 69 years of dormancy, a modest Volcanic Explosivity Index 3 event. It melted glacial ice into lahars that raced downhill at about 50 kilometers per hour and engulfed Armero, killing about 23,000 people. Volcanologists had warned authorities weeks in advance, so it is widely regarded as a preventable disaster.

Pinatubo on Luzon climaxed on 15 June 1991 with an ash column about 40 kilometers high and a Volcanic Explosivity Index of 6. It was the second-largest eruption of the 20th century, and the sulfur dioxide it injected into the stratosphere cooled global temperatures by about 0.5 degrees Celsius over two years. It is considered one of the best forecast major eruptions in history, and the recorded death toll was 847.

The path closes with Kilauea's Lower Puna eruption, which began on 3 May 2018 with lava fountains up to 300 feet high from 24 fissures near Leilani Estates. About 2,000 residents evacuated and about 700 homes were destroyed, and lava filled Kapoho Bay and evaporated Green Lake. No deaths were confirmed, but it was the most destructive volcanic activity in the United States since Mount St. Helens in 1980.