Sunday, June 17, 2007
Fourpeaked volcano alert status dropped to green level
The Alaska Volcano Observatory has dropped the advisory status to normal for Fourpeaked Volcano, a volcano about 100 miles south of Homer that became active last fall. Fourpeaked probably last erupted 10,000 years, scientists said. On the four-color aviation code, Fourpeaked was downgraded to green.
Scientists were surprised last September when many Homer residents reported steam rising from the mountain near Cape Douglas, visible looking south toward lower Cook Inlet.
AVO scientists installed seismometers, pressure sensors and a Web camera near Fourpeaked, and collected gas samples on flights over the volcano. Based on a drop in small earthquakes from 33 in March to seven in May, AVO said in a release scientists now believe Fourpeaked is returning to quiescence.
They still aren't sure exactly what happened, said Stephanie Prejean, a U.S. Geological Survey seismologist with AVO.
"Specifically what happened in September is questionable," she said.
Most likely Fourpeaked gave off steam, gases and old volcanic ash from previous eruptions stirred up by the steaming. A full eruption with magma rising to the surface, as happened with Augustine Volcano in 2005 probably did not happen, Prejean said.
Based on anecdotal accounts from longtime fishermen, AVO now thinks Fourpeaked could have given off steam in the 1960s. After reports of the 2006 event, two fishermen told AVO they saw it steaming then.
"We have been able to learn more about the volcano because of the public response," Prejean said. "That's been one interesting part of the story."
The Alaska Volcano Observatory is a cooperative program of USGS, the University of Alaska Fairbanks Geophysical Institute and the Alaska Division of Geological and Geophysical Surveys. For more information, visit its Web page at http://www.avo.edu/.
Michael Armstrong can be reached at michael.armstrong@homernews.com.
Scientists were surprised last September when many Homer residents reported steam rising from the mountain near Cape Douglas, visible looking south toward lower Cook Inlet.
AVO scientists installed seismometers, pressure sensors and a Web camera near Fourpeaked, and collected gas samples on flights over the volcano. Based on a drop in small earthquakes from 33 in March to seven in May, AVO said in a release scientists now believe Fourpeaked is returning to quiescence.
They still aren't sure exactly what happened, said Stephanie Prejean, a U.S. Geological Survey seismologist with AVO.
"Specifically what happened in September is questionable," she said.
Most likely Fourpeaked gave off steam, gases and old volcanic ash from previous eruptions stirred up by the steaming. A full eruption with magma rising to the surface, as happened with Augustine Volcano in 2005 probably did not happen, Prejean said.
Based on anecdotal accounts from longtime fishermen, AVO now thinks Fourpeaked could have given off steam in the 1960s. After reports of the 2006 event, two fishermen told AVO they saw it steaming then.
"We have been able to learn more about the volcano because of the public response," Prejean said. "That's been one interesting part of the story."
The Alaska Volcano Observatory is a cooperative program of USGS, the University of Alaska Fairbanks Geophysical Institute and the Alaska Division of Geological and Geophysical Surveys. For more information, visit its Web page at http://www.avo.edu/.
Michael Armstrong can be reached at michael.armstrong@homernews.com.
# posted by kevin : 8:27 PM
