Katla Volcano - Iceland

More immediate than concern for an eruption of the supervolcano that is Yellowstone National Park: the volcano on Iceland, which is the sole place on Earth where a mid-ocean ridge is above sea-level.

The AP reports:

REYKJAVIK, Iceland - Blasts of lava and ash shot out of a volcano in southern Iceland on Monday and small tremors rocked the ground, a surge in activity that raised fears of a larger explosion at the nearby Katla volcano.

Scientists say history has proven that when the Eyjafjallajokull volcano erupts, Katla follows — the only question is how soon. And Katla, located under the massive Myrdalsjokull icecap, threatens disastrous flooding and explosive blasts when it blows...

Like earthquakes, predicting the timing of volcanic eruptions is an imprecise science. An eruption at the Katla volcano could be disastrous, however — both for Iceland and other nations.

Iceland's Laki volcano erupted in 1783, freeing gases that turned into smog. The smog floated across the Jet Stream, changing weather patterns. Many died from gas poisoning in the British Isles. Crop production fell in western Europe. Famine spread. Some even linked the eruption, which helped fuel famine, to the French Revolution. Painters in the 18th century illustrated fiery sunsets in their works.

The winter of 1784 was also one of the longest and coldest on record in North America. New England reported a record stretch of below-zero temperatures and New Jersey reported record snow accumulation. The Mississippi River also reportedly froze in New Orleans.

"These are Hollywood-sort of scenarios but possible," said Colin Macpherson, a geologist with the University of Durham. "As the melt rises, it's a little like taking a cork out of a champagne bottle."

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