Posted on 04/01/2002 3:57:12 AM PST by kattracks
MENLO PARK, Calif., Mar 31, 2002 (United Press International via COMTEX) -- Ground near the long-dormant Three Sisters volcano in the central region of Oregon's Cascade Mountains has risen approximately 4 inches (100 millimeters) in a 6 by 12 mile (10 by 20 km) parcel since 1998, meaning that magma, underground lava, has flowed into the area, according to a team of researchers from the U.S. Geological Survey.
"It hasn't erupted in about 1,500 years, so it's a truly dormant volcano. Yet there's something going on there," said geologist Charles Wicks Jr., lead author of a report in the American Geophysical Journal.
"Right now in the Cascades, the only volcano that we know is restless is Three Sisters, based on the deformation," said co-author, geologist Daniel Dzurisin at the USGS Cascade Volcano Observatory in Vancouver, Wash.
The researchers said it's far too early to tell if this swelling and movement of magma presages a volcanic eruption. It might simply "freeze out," said Wicks, meaning the magma flow might simply stop.
The groundswell was observed by satellite radar images, a new technique that Dzurisin said would help scientists track such deformations.
"We now have a tool that allows us to see this kind of deformation around volcanoes, which we've suspected for a long time. But in the past we haven't been able to observe it unless there was accompanying seismicity," said Dzurisin, referring to the earthquakes that occur when the magma breaks through the rocky crust prior to eruptions. Such quakes are often a warning of an impending eruption.
"As far as I know this type of observation hasn't been made any other place. We don't know if this type of uplift occurs fairly frequently at similar types of places around the world. This type of thing may be relatively common, but we don't know," said University of Washington geophysicist Stephen Malone, who is familiar with the finding but is not connected with the published research.
He noted that geologists are installing seismometers in the area to monitor for earthquakes.
While the Three Sisters is only about 70 miles (130 kilometers) from Mt. St. Helens, which erupted in 1980, there is no direct physical connection between the two. The Cascades are volcanic because the Pacific tectonic plate slides under the North American plate and is melted by the heat of the Earth's interior, thus producing magma that rises to the surface.
While geologists say that tracking such groundswells is important for basic understanding of the way volcanoes work, there are important practical benefits as well.
"Ultimately the goal is mitigate volcanic hazards, and the way we can do that is to understand the processes that lead up to eruptions better. We hope that by being able to see ground deformation like this we might be able to extend the warnings that we might give," said Dzurisin.
(Reported by Harvey Black in Madison, Wisc.)
Copyright 2002 by United Press International.
It shouldn't be at all surprising to see new eruptions in the area. It might be a good idea to sell that property in Bend or Sun River now.
Most assuredly! I mean that's at least what the three sisters will need. We may even need special legislation passed at both the state and federal levels managing this magma issue.
South Sister is on the left.
I was in Wasginton state west of Vancouver when the earquake and eruption up there occured. I am glad to run across this thread, the scale of the St. Helen's blast was awesome.
I would hate to be in Eugene if it went Pompeii.
I like to bus up to McKenzie Bridge on the city bus that leaves Eugene zero dark thirty and bicycle up to 242 and come back the new route to catch the last bus of the day back to Eugene.
It is one of my favorite areas here in Oregon, and I know the forests up there well, and have climbed the South Sister several times.
[Graphic,201K,JPG, click to enlarge]
This radar interferogram shows a pattern of ground uplift centered about 3 miles (5 km) west of South Sister volcano in central Oregon. Each full color band from blue to red represents about 2.8 cm (slightly more than 1 inch) of ground movement in the direction of the radar satellite. In this case, four concentric color bands show that the surface moved toward the satellite (mostly upward) by as much as 10 cm (about 4 inches) sometime between August 1996 and October 2000. No information is available for uncolored areas, where forest vegetation or other factors hinder the acquisition of useful radar data. A numerical model places the source of the uplift about 4 miles (7 km) beneath the ground surface. The most likely cause is magma accumulation in the Earth's crust, a process that has been observed with radar interferometry at several other volcanoes worldwide. There is no immediate danger of a volcanic eruption or other hazardous activity. The U.S. Geological Survey, in cooperation with the U.S. Forest Service, is analyzing additional information and installing new monitoring instruments to determine if the uplift is continuing. The interferogram was produced by Wicks and others (2001) using radar images from the European Space Agency's ERS satellites.
In Calif. it was fires, mud slides, earthquakes. Here in Vegas you dry up and blow away and we even had an earthquak here a few years ago.
'Tornados in other states, hurricans in Florida.
I am in love with Oregon. True Love star crossed kind of thing.
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OK, Panic!
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