Mixing magma holds key to historic eruptions

Posted by: Saving Water SA (Cape Town, South Africa) – partnered with Water Rhapsody conservation systems – 03 August 2010

A new study has found that a mixing of two different types of magma is the key to the historic eruptions of Mount Hood, Oregon’s tallest mountain, and that eruptions often happen in a relatively short time – weeks or months – after this mixing occurs.

Mount Hood is the highest mountain in Oregon at 3429 metres

This behavior is different from that of most other Cascade Range volcanoes, including Mount Hood’s nearby, more explosive neighbor, Mt. St. Helens.

The research results are reported this week in the journal Nature Geoscience by geologists from Oregon State University (OSU) and the University of California at Davis, in work supported by the National Science Foundation (NSF).

“These results clarify details of the processes that trigger Mount Hood eruptions,” said Sonia Esperanca, program director in NSF’s Division of Earth Sciences, which funded the research. “Similar triggering processes may occur in several of Earth’s most active volcanoes.”

“The data will help give us a better road map to what a future eruption on Mount Hood will look like, and what will take place before it occurs,” said Adam Kent, a geoscientist at OSU. “It should also help us understand the nature of future eruptions and what risks they will entail.” Continue reading

Global temperatures unaffected by volcanic ash

Posted by: Saving Water SA (Cape Town, South Africa) – partnered with Water Rhapsody conservation systems – 21 April 2010

The volcanic ash cloud from the Icelandic volcano is not expected to have an impact on global temperatures.

Photo by Sverrir Thor under Ceative Commons licence 2.0

The volcano, located under the Eyjafjallajokull glacier has produced a 10-kilometre high plume of ash and rock that extends across most of northern Europe. While the particles may have an effect on local temperatures in the short-term, experts don’t believe it will have the same impact as the Pinatubo eruption two decades earlier that resulted in a 10% reduction in sunlight reaching the Earth’s surface, and a 0.4°C drop in global average temperatures.

Dr Blair Trewin of the National Climate Centre in Melbourne says, in its current form the ash cloud is unlikely to have the same impact on global temperatures. “For a volcano to have a significant global cooling effect it has to get its ash up into the stratosphere,” he says. “If it doesn’t, the ash will get rained out fairly quickly.”

Despite spewing an estimated 150,000 tons of carbon pollution a day into the atmosphere, the volcano may actually result in a net reduction of carbon pollution because of all the flights the volcano is grounding in Europe. Those flights would have a bigger carbon footprint than the volcano.

Dr Jeff Masters, Director of Meteorology at Weather Underground says the eruption isn’t expected to have a significant impact on weather patterns in the northern hemisphere. “However, the ash could bring spectacular sunsets to Europe over the next week, and to North America by sometime next week, as the jet stream wraps the ash cloud eastwards across the northern hemisphere.”