Blow Hard: 11 of the Biggest Volcanic Eruptions of All Time

To witness nature’s potential for catastrophic destruction, one need only observe the volcano. Often likened to gateways to the underworld, there are approximately 1500 active volcanoes worldwide. Beyond ejecting ash and molten rock, they can drastically shift climate patterns and influence global history.

The majority are stratovolcanoes—tall, conical mountains formed by accumulated layers of ash and lava. Their soft structure enables pressure to build internally, leading to sudden, violent eruptions with minimal warning. Their steep inclines also trigger mudflows and deadly pyroclastic surges, making them the most hazardous type of volcano. (On the other hand, shield volcanoes, such as those in Hawaii, are flatter and typically release slow-moving lava through fissures.)

For proof, consider these fiery volcanic landmarks, listed in no specific sequence.

1. Novarupta // Alaska

Volcanic eruptions can be evaluated based on their impact or the sheer volume of material expelled. In terms of output, the Novarupta (or Katmai) eruption, which started on June 6, 1912, was a colossal event. Over 60 hours, it discharged more than 13 cubic kilometers of lava, averaging 573.2 million tons per hour. Approximately 100 miles away in Kodiak, ash deposits exceeded 1 foot in depth. The ash surrounding the volcano solidified into the “Valley of 10,000 Smokes,” dotted with steaming fumaroles (vents releasing gas or steam). The eruption also caused a atmospheric haze that reportedly lowered summer temperatures. It remains the largest eruption of the 20th century, scoring a 6 on the Volcanic Explosivity Index (VEI), which rates eruptions from 1 (least explosive) to 8 (most explosive).

2. Krakatoa // Indonesia

Indonesia is home to two of the most devastating volcanic eruptions of the 19th century, a grim record fueled by its 150 active volcanoes, the highest number globally. One such event took place in August 1883, when Krakatoa (also known as Krakatau) erupted on an island near Sumatra. Approximately five cubic miles of lava were ejected 50 miles into the atmosphere, triggering enormous tsunamis. In the months before the catastrophic eruption, the volcano issued several warnings through smaller explosions, with ash plumes rising only seven miles high. The first major explosion, rated a 6 on the VEI scale, occurred on August 26, destroying two-thirds of the island. Subsequent eruptions blanketed the globe in ash, causing global temperatures to drop by several degrees. The disaster claimed around 36,000 lives, including 31,000 who died in the tsunamis that ravaged nearby islands.

3. Mount Tambora // Indonesia

Mount Tambora’s eruption in April 1815 in Sumbawa, Indonesia, showcased the brutal power of volcanoes. Before the catastrophic blast, which scored a VEI of 7, soldiers in the area mistook the thunderous noises for cannon fire and prepared for battle. In a sense, they were right. Tambora ejected 12 cubic miles of gases and debris 25 miles into the sky, spawning massive tsunamis and blanketing nearby islands in ash. Around 10,000 people died instantly, with the death toll rising to 90,000 due to ensuing famine. Scientists now believe the eruption drastically altered global weather patterns, causing crop failures and food shortages as far away as North America and Europe. In 1816, with Tambora’s ash still lingering in the Northern Hemisphere, poet Lord Byron challenged his literary circle, including Mary Shelley, to craft dark tales. Shelley began writing Frankenstein.

4. Mount St. Helens // Washington

On May 18, 1980, Mount St. Helens unleashed its fury, marking a catastrophic event in North America. Earlier tremors had triggered avalanches, followed by thousands of smaller quakes that weakened the mountain’s structure. A 5.1-magnitude earthquake then caused the summit to erupt, sending ash and scorching gases into the atmosphere. The explosion sheared off 1314 feet from the mountain’s height, devastating 230 square miles and damaging 158 miles of highways. The disaster claimed 57 lives and cost over $1.1 billion in recovery efforts. With a VEI of 5, this remains the deadliest volcanic eruption in U.S. history.

5. Mount Vesuvius // Italy

Though its Volcanic Explosivity Index ranks it at a 5, Mount Vesuvius’s eruption in 79 CE holds a unique place in history. On August 24, the volcano erupted, transforming the Roman cities of Pompeii and Herculaneum into eerie snapshots of ancient life. Pompeii, known for its fertile lands, and Herculaneum, a retreat for Rome’s wealthy, were both buried under ash. Many residents stayed, hoping to survive, but a subsequent blast unleashed toxic gases and fiery debris, entombing the cities in mud and ash. Rediscovered in the 18th century, Pompeii and Herculaneum continue to yield new insights into their tragic final moments.

6. Mount Pinatubo // Philippines

Mount Pinatubo’s eruption on June 15, 1991, was a catastrophic event, scoring a 6 on the VEI. This massive explosion devastated a densely populated region of Luzon, Philippines. Following a series of earthquakes and magma rising 20 miles to the surface, Pinatubo unleashed over five cubic kilometers of gas-powered lava. Pyroclastic flows deposited ash and pumice layers exceeding 660 feet thick, while tropical storms triggered massive mudslides. Buildings collapsed under the weight of wet ash. Thanks to accurate scientific predictions, timely evacuations saved thousands of lives.

7. Laki // Iceland

Laki, located in what is now Vatnajökull National Park in Iceland, stands out for its prolonged activity. Rather than a single massive eruption, Laki produced a series of lava flows and explosions lasting over eight months in 1783 and 1784, with a VEI of 4. The eruption generated enough lava to cover the entire city of Boston to a depth of 207 feet. Toxic gases caused acid rain that burned vegetation and irritated skin, while livestock deaths led to a famine that may have killed a quarter of Iceland’s population. Like Tambora, Laki’s ash disrupted global weather patterns, contributing to food shortages in Europe and possibly fueling the unrest that led to the French Revolution.

8. Mount Pelée // Martinique

Mount Pelée stood ominously over St. Pierre, a tranquil town on Martinique, like a disaster waiting to happen. In early May 1902, a fierce lahar—a torrent of volcanic debris and water—erupted from the mountain, flooding a sugar refinery and reaching the ocean, which triggered a tsunami. The chaos drove wildlife, including giant insects and venomous snakes, into the town. Snakebites claimed around 50 lives. Despite these warnings, the island’s governor reassured residents of their safety. Tragically, he was mistaken. On May 8, the volcano erupted with a VEI of 4, releasing a deadly wave of scorching gas and debris that annihilated St. Pierre and killed 30,000 people in mere minutes.

9. Nevado del Ruiz // Colombia

Spanning 77 square miles, Nevado del Ruiz is a massive stratovolcano. It has erupted multiple times since 1570, but the most devastating event took place on November 13, 1985. As magma rose toward the summit, the intense heat melted the vast glaciers covering the peak. The resulting meltwater formed destructive lahars, merging with rivers to create catastrophic mudflows in the valleys. During this VEI 3 eruption, the town of Armero was completely destroyed, and 23,000 people perished in the floods.

10. Mount Tarawera // New Zealand

On June 10, 1886, the residents of New Zealand’s North Island were stunned when Mount Tarawera erupted, creating fissures stretching 10 miles from the epicenter. The VEI 5 explosions were audible up to 310 miles away, marking the largest volcanic event in the country’s history. The eruption also spawned eerie tales. Some European settlers claimed to have seen a Māori war canoe on Lake Tarawera before the eruption. They called out to the sailors, who did not respond. After the disaster, it was revealed that no such canoe had ever been spotted on the lake.

11. Yellowstone // Wyoming

Yellowstone National Park sits atop a supervolcano, which is thought to have erupted significantly at least three times in human history: 2.1 million years ago (with a VEI of 8), 1.3 million years ago, and 664,000 years ago. The most recent eruption created a crater measuring 34 by 50 miles. Currently, the magma beneath Yellowstone lies five miles below the surface, leading some to theorize that a future eruption—though uncertain—could unleash a super-eruption (rated VEI 8 or higher), potentially burying the Rockies in ash.