You wouldn't like supervolcanoes when they're
angry. These massive eruptors—100 times more powerful than Mount St. Helens—can blanket entire continents with ash and spew so many planet-cooling
aerosols into the atmosphere that they trigger "volcanic winters" that can last for a decade or more. Now we have another reason to fear them: They may blow their top with only a few centuries of warning—not the 100,000-year heads-up
that many geologists had counted on. The discovery, reported online today in PLoS ONE, is based on a multitude of quartz crystals found in 11
samples of frothy lava left in the wake of the supereruption that created a massive crater in east-central California about 760,000 years ago (part of the
Long Valley Caldera, which measures about 32 kilometers long and 16 kilometers wide, shown.) The size distribution of the quartz crystals, as well as the
concentrations of titanium within them, suggest they formed in a geologically short period of time—certainly less than 10,000 years, and possibly in as
little as 500 years. Despite this short fuse, the researchers say, there's no question that scientists would notice the warning signs of an impending
supereruption, including the migration upward and accumulation of large volumes of molten rock just a few kilometers below Earth's surface.
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