This Is How Volcanic Eruptions Affect Your Body

In early 2022, a volcanic eruption off the coast of the small island nation of Tonga released an explosion as powerful as a hundred atomic bombs, according to NASA. "This is a preliminary estimate, but we think the amount of energy released by the eruption was equivalent to somewhere between 4 to 18 megatons of TNT," said NASA scientist Jim Garvin. "That number is based on how much was removed, how resistant the rock was, and how high the eruption cloud was blown into the atmosphere at a range of velocities."

As destructive as this large eruption was, it might be seen as relatively minor by historical standards. There were few reported casualties in the immediate aftermath, and most were thousands of miles away, in Peru, which experienced dangerous currents after the Tonga eruption caused a tsunami, per The New York Times. In the deadliest explosions in recorded history — Mount Tambora in 1815, Huaynaputina in 1600 — thousands if not millions of people died, according to Business Insider.

How do volcanic eruptions affect you? It depends on how far away you are from the blast, but with a big enough eruption, everyone on Earth is affected.

Close to the blast: tsunamis, asphyxiation, and ash

After the Tonga eruption, when residents felt the blast of the volcano, they knew they had to get to higher ground, according to The New York Times. The volcano was underwater, so the blast would almost definitely cause a tsunami.

In an above-ground volcanic explosive eruption, the biggest danger is quick-moving volcanic ash flow. In the 1980 Mount St. Helens eruption in Washington, for instance, most of the 57 deaths were due to asphyxiation, according to USA Today. When a mountain is snow-capped, the resulting mudflows can also be highly destructive, according to EarthSky.

More deaths can occur in the time after a blast, after infrastructure has been damaged. Communication in the early days after the Tonga eruption was scant. The offshore blast damaged a pivotal undersea cable to the nation, making the country almost totally dependent on satellite for phone and internet. But this task was made more difficult by the clouds of soot and vapor that hung in the air over the island, blocking satellites from access.

The biggest problem Tonga faced, however, was the ash from the volcano. After the eruption, rocks and ash began to fall from the sky; the islands were coated in ash, reducing the availability of potable drinking water, according to the Times.

Farther away: climate change and famine

Scientists believe that it's unlikely that the Tonga eruption will significantly cool the planet, as other volcanic eruptions have temporarily done, according to The New York Times. It simply did not release enough sulfur dioxide into the atmosphere. But in the past, large volcanic eruptions have dramatically cooled the planet for years at a time, causing famines and even spreading disease.

In 1815, the Tambora volcano in Indonesia erupted, according to National Geographic. It was one of the largest and deadliest volcanic eruptions on record, with an estimated death toll of more than 71,000. In the aftermath, the Earth cooled by 3 degrees Fahrenheit, and 1816 was known as "the year without a summer," according to CNN. Weather patterns changed, with some regions getting dryer and others wetter. Famine and disease resulted.

This wasn't the first time a volcanic eruption had a large effect on the global climate, nor was it the last, as the Mount Pinatubo eruption in 1991 cooled the planet by an estimated 0.9 degrees Fahrenheit (via Reuters). In A.D. 536, a volcano eruption in Iceland caused the sun to be almost completely blotted out; contemporary accounts compared it to a solar eclipse that lasted the entire year (per Science). Summer temperatures fell several degrees. Starvation was common, and the bubonic plague was rampant. No wonder scientists have described that year as the worst time for humans to be alive.