How a single eruption can reshape the world and destroy everything in its path

Nature · Published 7 October 2026 Swipe more like this →

In short: When magma escapes the earth's surface, the results can be catastrophic. From explosive blasts that launch 8-ton boulders to deadly mudflows known as lahars, volcanic activity can transform landscapes in minutes, burying cities under ash and altering the very terrain we call home.

Volcanic eruptions are categorized by their intensity and the way they release pressure. Effusive volcanoes, such as Hawaii's Mauna Loa, release lava that flows steadily. While these flows can destroy farms, houses, and roads, fatalities are rare because the lava is often slow enough for people to outrun. In contrast, explosive eruptions are far more lethal and unpredictable.

The power of an explosive eruption is immense. These events can shoot particles up to 20 miles into the atmosphere and hurl 8-ton boulders more than half a mile away. A significant danger is the lahar—a fast-moving, deadly mudflow that rolls downhill, clearing everything in its path. These eruptions can also trigger massive landslides and avalanches of hot ash, gas, steam, and rock that can mow down giant trees up to 15 miles away.

The environmental impact extends far beyond the immediate blast zone. Volcanic ash can carpet the ground, causing buildings to collapse and contaminating water supplies. It is also known to cause airplane engines to fail and damage electronics. For example, the 1980 eruption of Mount St. Helens in Washington—which occurred after 123 years of hibernation—destroyed 230 square miles of forest in minutes and sent ash over a 22,000 square mile area, affecting cities 370 miles away.

Despite this destruction, volcanoes are also agents of creation. They are responsible for forming mountains and islands, and over time, they leave behind incredibly fertile land. The largest volcanic explosions in Earth's history have left behind unfathomably large calderas, marking the sheer scale of these geological forces.

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