Reply #42: Rainier would be bad, but Yellowstone would be devistating

[Ediacara]

Rainier has a higher chance in the near term of erupting, and since it's close to 4 major metropolitan areas (Portland, Seattle, Vancouver, and Spokane) it could kill many thousands.

Yellowstone is a completely different kind of volcano though. Rhyolitic magma (which is what's under Yellowstone) is increadibly viscous, so they doesn't erupt very frequently, and when it does, it's like a nuclear bomb. The magma under Rainier (and the rest of the Cascades) is Andesitic, which is considered intermediate between Basaltic (like Hawai'i, very fluid magmas) and Rhyolitic magmas.

Mount Saint Helens was pretty explosive, but a virtual hickup compared to Yellowstone (or any other Rhyolite volcano). Millions of tons of rock will be vaporized and thrust into the air, and ash will be up to 30 metres thick in most of Montana, Idaho, and Wyoming. Ash will fall in the Pacific, Northern Mexico, Central Canada, and probably as far away as New York City. The earthquake will be felt through most of North America.

The ash fall will lead to massive North American crop failures in the first one or two years, and may reduce global temperatures worldwide for decades. As many as one million may die in the initial blast, fifteen million more may die for ash inhalation, and many millions more will die of starvation.

The United States will probably cease to exist.

Yellowstone is some pretty dangerous shit.