By Joel Achenbach | Washington Post
Yellowstone National Park sits squarely over a giant, active volcano. This requires attention.
Yellowstone has been a national park since 1872, but it was only in the 1960s that scientists realized the scale of the volcano – it’s 44 miles across – and not until the 1980s did they grasp that this thing is fully alive and still threatens to erupt catastrophically. Yellowstone is capable of eruptions thousands of times more violent than the Mount St. Helens eruption of 1980. The northern Rockies would be buried in multiple feet of ash. Ash would rain on almost everyone in the United States. It’d be a bad day. Thus geologists are eager to understand what, exactly, is happening below all those volcano-fueled hot springs and geysers.
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Obviously they’d like to know if and when Yellowstone will blow again, and with what level of explosiveness. A major eruption would be a low-probability, high-consequence event, a proverbial Black Swan, something that could have societal and planetary effects. The problem for scientists is that these big “supervolcano” eruptions rarely happen, and the most important action is out of sight, many miles below the surface, involving chaotic forces, complex chemistry and enigmatic geological features.
One new study has offered insight on Yellowstone’s hidden architecture. It modeled the way magma rises from deep in the Earth’s interior and creates two large chambers of partially melted rock beneath the surface of the national park.
These two magma chambers are stacked, and separated by a layer (called a “sill,” like a window sill) of non-melted rock. The magma rising from the Earth’s mantle flows easily and doesn’t hold much gas. It cools …read more
Source:: The Mercury News – Nation, World