My OperaNovarupta, 20th Century's Most Powerful Volcanic Eruption
Friday, October 6, 2006 10:39:52 AM
In June 1912, Novarupta erupted in the largest volcanic eruption of the twentieth century. Novarupta, meaning "new eruption", is a volcano located on the Alaska Peninsula in the Katmai area, about 470 km southwest of Anchorage. Its eruption of June 6–June 8, 1912, was ten times more powerful than the 1980 eruption of Mount St. Helens and led to the formation of this 841 m volcano. About 15 km³ of volcanic material was ejected over two and a half days. The 1815 eruption of Tambora. however, had displaced about seven times as much material. The 1883 eruption of Indonesia's Krakatoa displaced twice as much as Novarupta. Novarupta's 1912 eruption has been rated a 6 on the Volcanic Explosivity Index. Magma from underneath the Mount Katmai area was drained away to Novarupta, resulting in a collapsed 3 × 4 km caldera.Almost a hundred years later, researchers are paying attention. Novarupta is near the Arctic Circle and its impact on climate appears to be quite different from that of "ordinary" tropical volcanoes.
When a volcano erupts, it blows sulfur dioxide into the air. If the eruption is strongly vertical, it shoots that sulfur dioxide high into the stratosphere more than 16 km above Earth. In the stratosphere, sulfur dioxide reacts with water vapor to form sulfate aerosols. Because these aerosols float above the altitude of rain, they don't get washed out. They linger, reflecting sunlight and cooling Earth's surface. This can create a kind of nuclear winter (a.k.a. "volcanic winter") for a year or more after an eruption. Aerosols from an arctic eruption such as Novarupta tend to stay north of 30N. This would lead to an abnormal cooling of the northern hemisphere. Cooling of the northern hemisphere would set in motion a chain of events involving land and sea surface temperatures, the flow of air over the Himalayan mountains and, finally, clouds and rain over India. It is an extremely complex situation and supercomputers are needed to do the calculations.
- Terradaily of 4 October 2006 at http://www.terradaily.com/reports/Novarupta_And_The_Next_Nuclear_Winter_999.html
- LiveScience of 5 October 2006 at http://www.livescience.com/forcesofnature/061005_novarupta_india.html
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