yellowstone

Mauna Loa in Hawaii rises 4,170 metres above the sea — but that's only the tip. Measured from its true base on the ocean floor, it stands roughly 17 kilometres tall, more than twice Everest's height above sea level, and is so heavy it has pushed the seabed downward beneath it. It may not even be the largest volcano on Earth by volume. And lurking beneath Yellowstone is something that isn't a mountain at all: a supervolcano whose eruptions are measured not in metres but in continents.

Toba, Yellowstone, Tambora, Krakatau, and Pinatubo compared by volume, climate effect, and death toll, with a plain explanation of the VEI scale and why the biggest eruption is rarely the deadliest.

The Yellowstone supervolcano produces a major eruption roughly every 600,000–800,000 years. The last was 631,000 years ago. If it erupted today, parts of the western United States would be buried in ash, global temperatures would drop, and agriculture would collapse for years.