October 1, 2013
Volcano Experts Identify Source Of Largest Eruption In Past 3,700 Years
Brett Smith for redOrbit.com - Your Universe Online
Vulcanologist have identified the source of the largest volcanic eruption in the last 3,700 years, which was said to have created a ‘Pompeii of the East,’ according to a newly published report in Proceedings of the National Academy of Sciences.
Using a wide range of scientific techniques, the study researchers were able to identify the Samalas volcano in Indonesia as the source of a 1257 AD eruption that sent volcanic ash around the Earth from pole to pole.
“Until now we thought that Tambora was the largest eruption for 3,700 years," Lavigne said.
In the study, the international team used radiocarbon-dating results, volcanic ejecta chemistry and historical writings to reach their conclusion.
"This eruption was known by many different disciplines, many researchers," Lavigne said, "but the main problem may be that they worked individually. I think this is a key point for work on other eruptions. We had geologists, geochemists, geographers, historians, radiocarbon-dating specialists, and many others—all these researchers from different specialties to combine facts."
The epic eruption sent 10 cubic miles of material as high as 27 miles into the sky, eventually sprinkling back onto Earth. Near Mount Samalas, the debris settled into thick deposits that provided researchers with a picture of the way the eruption occurred.
The team was able to zero in on the eruption date by analyzing carbonized tree trunks and branches along the volcano’s flanks. The radiocarbon data confirmed the mid-13th century eruption date, as none of the samples were dated later than 1257. The radiocarbon analysis allowed for the elimination of other likely candidates, such as El Chichón and Okataina.
"We started with the ice cores," Lavigne said, "and we know from the [distribution near both poles] that the eruption was tropical."
Evidence provided by glass samples found in the ice cores allowed the team to rule out Ecuador's Quilotoa volcano.
"This just shows that there is a lot we don't know about volcanic eruptions, even what may seem like basic questions about some of these very big eruptions," said geologist Ben Andrews of the Smithsonian Institution's Global Volcanism Program, which maintains a public database of 10,000 years of volcanic eruptions. "This international team of scholars did a huge amount of work to help us understand this one."
Some historical Indonesian records describe a massive volcanic eruption that formed a caldera at Mount Samalas. The records describe ashfall and pyroclastic flows destroying Pamatan, capital of a regional kingdom, and surrounding lands. These historical records also allowed the team to narrow the date range considerably – stating that it took place before the end of the 13th century.