The Biggest Volcanic Eruptions in Human History

The January volcanic eruption near the island of Tonga is now being called the most powerful such event in 140 years. Authorities are still taking stock of the damage, both from massive ash plumes and a tsunami triggered by the blast. To be sure, volcanic eruptions can cause disaster on a shocking scale, as anyone who can remember the infamous 1980 eruption of Mount St. Helens can attest. Here are some of the eruptions throughout history that have left the biggest scars. 

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Mount Vesuvius has erupted eight times in the last 17,000 years, most recently in 1944, but the big one was in 17 A.D. One of the most violent eruptions in history, it destroyed the Roman cities of Pompeii and Herculaneum. Equally significant to its power is its historical significance. An eyewitness account written by the Roman historian Pliny the Younger — volcanologists now call similar episodes “Plinian eruptions” — is the earliest known surviving account of a major eruption. Also, there are the archaeologically priceless but impossibly creepy volcano “mummies” made from human beings frozen in time by pyroclastic flows of ash and pulverized pumice during their final moments on Earth. 

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The 1783 eruption of the Laki volcano in Iceland lasted eight months and spewed nearly nine cubic miles of basaltic lava up from the bowels of the planet. The cloud of volcanic ash it belched out for the better part of a year was documented as far away as Syria. In the fledgling nation of America, Ben Franklin noted the changes it caused in the atmosphere. The real trouble, however, was closer to the eruption. The blast discharged 80 times more sulphuric acid than Mount St. Helens. Acid rain caused widespread crop failure and Iceland's livestock died en masse from eating contaminated grass. About 9,000 people — about one in four human beings living in Iceland at the time — died of starvation as their land was transformed. 

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Mount Unzen is actually a group of overlapping active volcanoes. In 1792, an eruption caused enormous landslides that engulfed the city of Shimabara before falling into the sea. The collapse triggered a giant tsunami that caused even more death and destruction. It’s believed that the final tally is somewhere in the neighborhood of 15,000 dead. In the 1990s, the volcano began grumbling out of its slumber again. 

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Pressure and magma had been filling the void below Mount Tambora for centuries, and when that pressure finally burst through the surface, the result was the biggest and deadliest volcanic eruption in recorded human history. The Plinian eruption column stretched more than 30 miles high when the volcano released around 90 cubic miles of magma. The peninsula itself was essentially wiped out, with unstoppable and unsurvivable pyroclastic flows reaching the ocean on every side. The real damage, however, was lingering. It’s estimated that 100,000 people died of widespread famine in the ensuing months when much of Europe entered the “Year Without Summer.” The global temperature dropped by 3 degrees Celsius in 1816 thanks to Tambora’s curtain of ashes blocking out the sun.

In May 1883, after years of intense seismic activity in the Sunda Strait, the massive volcano on the uninhabited island of Krakatoa exploded in a furious eruption. It sent a cloud of ash 50 miles into the air, blanketing out the sun for more than two days across the region. Its sound — the loudest ever recorded in modern history — was heard for thousands of miles all over the world. The eruption destroyed the volcano and the island itself, which collapsed into a caldera. It caused all-consuming pyroclastic flows and triggered massive tsunamis that wiped out hundreds of towns and villages in the region and killed around 36,000 people. 

Until the turn of the 20th century, inhabitants of the town of St. Pierre on the French Caribbean island of Martinique mostly ignored their giant neighbor Mount Pelée, which loomed less than five miles away. Over the centuries, it had grumbled a few times, but on May 8, 1908, the people of St. Pierre would live to regret their complacency — but not for long. Before the blast, there was no shortage of bad omens. Pre-eruption tremors and steam releases sent wildlife — including giant insects and snakes — scurrying off the mountain and into St. Pierre, where dozens of people were killed by vipers reaching six feet long. Finally, the volcano exploded in a violent eruption that generated an avalanche of gas, debris, ash, rock, and fire reaching temperatures of 750 Fahrenheit. It annihilated the town of St. Pierre in an instant, killing nearly all 30,000 inhabitants.

No other historical eruption in North America can compare to the one that created the Novarupta Volcano in 1912. The biggest eruption on Earth in the 20th century, it produced 30 times more magma than Mount St. Helens. It remains one of the most scientifically important incidents in history and continues to be a source of great discovery for volcanologists. It was the first time in history that a major eruption deposited pyroclastic flows on land instead of in the sea. 

Intense and escalating seismic activity in the spring of 1980 left little doubt that Mount St. Helens was going to blow, and on May 18, that’s exactly what happened. First, a massive earthquake triggered the largest debris avalanche ever recorded. That was followed by a Plinian eruption that lasted for nine hours. A lateral eruption, it blasted out the northern flank of the volcano, not the top, which destroyed the volcano’s top and side. 520 million tons of ash went airborne toward the east, blacking out all of Spokane. Two-hundred and thirty square miles of surrounding land were destroyed and 57 people were killed, many of which — including USGS volcanologist David A. Johnston — were killed in pyroclastic flows, which reached 80 miles per hour. 

Compared to the giants, the eruption of Nevado del Ruiz wasn’t particularly apocalyptic — but its side effects sure were. After much seismic activity and warnings from scientists to evacuate the nearby town of Armero that ultimately went unheeded, the volcano erupted on Nov. 13. Although the eruption itself was no Mount Vesuvius or Krakatoa, the incident served as a testament to the unpredictable nature of natural disasters. The eruption triggered massive mudslides that engulfed the town of Armero, killing more than 23,000 people. It was the worst natural disaster in South American history and one of the deadliest eruptions ever. 

On June 15, 1991, a rumbling Mount Pinatubo grew and grew until it exploded in the biggest volcanic eruption on Earth in 100 years. Super-pressurized, gas-charged magma burst through and a cloud of volcanic ash soared 28 miles in the sky. Pyroclastic flows — fast-moving avalanches of superheated gas, ash, rock, fire, and pulverized pumice — roared down the mountain and blanketed the countryside. Some valleys piled up more than 660 feet of ash. The ash and debris spread far and wide, and the weight of it all caused thousands of roofs to collapse. Those collapses were responsible for most of the more than 840 deaths attributed to the eruption.

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On Jan. 15, an underwater volcano near Tonga exploded, sending a plume of ash and steam over 12 miles into the atmosphere in an event that was even captured on satellite. It also triggered tsunami warnings as far away as Japan, the United States, and Peru, and covered Tonga's main island of Tongatapu with surging waves and a layer of volcanic ash. At least three people were killed, and it triggered unusual pressure waves around the world for six days. The eruption is now being called the biggest in 140 years, right behind the 1883 Krakatoa eruption. Scientists continue to study the Tonga eruption's effect on the lower atmosphere and even space, where it created hurricane-force winds.