Deadliest Volcanic Eruptions in History

Pyroclastic flows are responsible for more volcanic deaths than any other hazard. These superheated avalanches of gas, rock fragments, and volcanic ash can reach temperatures of 700°C (1,300°F) and travel at speeds exceeding 700 km/h (430 mph), making them virtually impossible to outrun.

The most devastating example on this list is the 1902 eruption of Montagne Pelée on the Caribbean island of Martinique. On the morning of May 8, a massive pyroclastic flow — described at the time as a "nuée ardente" (glowing cloud) — swept down the mountainside and engulfed the city of Saint-Pierre in under two minutes. Of the city's approximately 30,000 inhabitants, only two survived.

The disaster shocked the world and fundamentally changed the scientific understanding of volcanic hazards.

While pyroclastic flows dominate public imagination, water-related hazards — tsunamis and lahars — have produced some of the highest individual death tolls in volcanic history.

The 1883 eruption of Krakatau generated tsunamis up to 30 meters (100 feet) high that devastated coastal towns across the Sunda Strait, killing an estimated 36,000 people. The caldera collapse that produced these waves was so violent that the sound was heard 4,800 km (3,000 mi) away in Rodrigues Island near Mauritius — the loudest sound in recorded human history. The tsunamis, not the eruption itself, accounted for over 90% of the deaths.

Lahars — fast-moving volcanic mudflows — are equally devastating. The 1985 eruption of Nevado del Ruiz in Colombia melted roughly 10% of the volcano's ice cap, sending lahars down river valleys at speeds up to 60 km/h (37 mph). The town of Armero, 74 km (46 mi) from the summit, was buried under 5 meters of mud.

Over 23,000 of its 29,000 residents perished. The tragedy was compounded by the fact that scientists had warned of the lahar risk months in advance, but evacuation orders were never issued.

The deadliest volcanic eruption in recorded history — Tambora in 1815 — killed more people through its climatic aftermath than through its immediate eruption. While approximately 12,000 people died directly from pyroclastic flows and ashfall on Sumbawa Island, an estimated 80,000 additional deaths resulted from famine and disease caused by the eruption's global climate impact.

Tambora injected an estimated 60 megatons of sulfur dioxide into the stratosphere, creating a veil of sulfuric acid aerosols that blocked sunlight worldwide. The following year, 1816, became known as the "Year Without a Summer." Crop failures struck across North America, Europe, and Asia. In parts of Indonesia, the ashfall destroyed crops entirely, triggering famine and a cholera epidemic.

The 1783 Laki eruption in Iceland produced a similar but more localized catastrophe. An eight-month-long fissure eruption released toxic fluorine gas that poisoned over 60% of Iceland's livestock. The resulting famine killed approximately 9,350 Icelanders — roughly a quarter of the population.

The volcanic haze drifted across Europe, contributing to crop failures and an estimated 23,000 additional deaths in Britain alone from respiratory illness.

These events demonstrate that the VEI scale alone cannot capture a volcano's destructive potential. Duration, gas composition, and atmospheric injection height all determine whether an eruption will have global consequences.

The 20th and 21st centuries have seen both devastating volcanic disasters and remarkable successes in volcanic hazard mitigation.

The 1991 eruption of Mount Pinatubo in the Philippines stands as the greatest success story in volcanic risk reduction. Scientists from the Philippine Institute of Volcanology and Seismology (PHIVOLCS) and the U.S. Geological Survey detected the eruption weeks in advance. Over 200,000 people were evacuated from the danger zone before the climactic VEI 6 eruption on June 15.

Despite being the second-largest eruption of the 20th century, Pinatubo's death toll (847) was a fraction of what it could have been — scientists estimate that without the evacuation, fatalities could have exceeded 20,000.

Contrast this with Nevado del Ruiz just six years earlier, where warnings went unheeded and 23,000 died. The Armero tragedy led directly to the establishment of new volcano monitoring programs across Latin America and the creation of international volcanic hazard alert protocols.

More recently, the 2022 eruption of Hunga Tonga-Hunga Ha'apai produced one of the most powerful explosions ever recorded — generating a volcanic plume that reached 57 km into the mesosphere and an atmospheric shockwave that circled the Earth multiple times. Yet only 6 people died, thanks to the volcano's remote submarine location and modern tsunami warning systems. This event, however, highlighted a new concern: submarine volcanic eruptions can generate atmospheric tsunamis and disruptions to global communications infrastructure.