Ultra-Plinian Eruptions: The Largest on Earth

Yellowstone's Central Plateau — the caldera — from Mount Washburn. NPS / John Good.

What they are

Ultra-Plinian eruptions are the largest volcanic eruptions of all — so voluminous that huge calderas collapse over the emptied magma chambers. Compared with Plinian eruptions, they are more intense, erupt faster, and throw higher eruption columns. They produce thick pyroclastic flows covering vast areas and can spread ash far and wide.

Supervolcanoes

Volcanic centers whose eruptions exceed 200 cubic miles (1,000 km³) are called supervolcanoes — typically massive calderas. Yellowstone's Lava Creek eruption 640,000 years ago formed a caldera about 30 by 45 miles (50 by 70 km), dwarfing the crater atop Mount St. Helens and even Mount Mazama's caldera.

More

• NPS: eruption classifications · previous: Plinian eruptions
• Crater Lake: Geodiversity Atlas · park · USGS Cascades Volcano Observatory
• Yellowstone: Geodiversity Atlas · the volcano · USGS Yellowstone Volcano Observatory

Sources

Based on "Ultra-Plinian Eruptions," part of the series Volcanic Eruption Styles, National Park Service; a work of the United States government in the public domain. A caldera size comparison adapted from a commercially published book is left out.