3 Sisters Oregon. Magma warning. shallower intrusion of magma or even to a

[junker]

small eruption....official press release in toto...


PRESS RELEASE -
March 24, 2004
March 2004 Earthquake Swarm at Three Sisters, Oregon
U.S. Geological Survey Cascades Volcano Observatory, Vancouver, Washington
University of Washington, Pacific Northwest Seismograph Network, Seattle, Washington
THREE SISTERS, OREGON, INFORMATION STATEMENT
At approximately 10 a.m. yesterday (Tuesday, March 23), an ongoing swarm of small earthquakes began in the Three Sisters volcanic center in the central Oregon Cascade Range. This activity poses no immediate threat to the public. As of this morning, the regional seismic network has detected approximately 100 earthquakes ranging in magnitude up to about 1.5. The rate of earthquakes peaked late yesterday and appears to be declining slowly. The earthquakes are occurring in the northeast part of an area centered 5 kilometers (3 miles) west of South Sister volcano in which the ground has been uplifted by as much as 25 cm (about 10 inches) since late 1997. On the basis of multiple lines of evidence, scientists infer that the cause of the uplift is the continuing intrusion of a modest volume of magma (molten rock). The magma appears to be accumulating at a depth of about 7 kilometers (4 miles) below the ground surface and now measures about 40 million cubic meters (about 50 million cubic yards) in volume. Until yesterday, only a few earthquakes have accompanied this process, but scientists have expected that swarms of small earthquakes such as the present one would eventually accompany the uplift. The most likely cause of the earthquakes is small amounts of slippage on faults as the Earth's crust adjusts to the slow ground deformation of the past 7 years. Heat and gases related to the magmatic intrusion have probably caused increases in fluid pressure deep underground, which also helps to trigger minor faulting events.
The processes that have been causing the uplift over the past seven years could eventually lead to shallower intrusion of magma or even to a volcanic eruption; however, both are unlikely without significantly more intense precursory activity. Scientists continue to monitor the situation closely and to evaluate data from field instruments.
Today scientists are deploying another seismometer in order to locate earthquakes more precisely. With the assistance of the Willamette and Deschutes National Forests, additional fieldwork over the next week will fix problems with some field instruments that resulted from the heavy winter snow-pack and will assess sites for new instruments.
Additional information, including maps and a volcanic-hazards assessment, may be found on the Internet at Web at URL:
http://vulcan.wr.usgs.gov/Volcanoes/Sisters/framework.html
Updates on Seismicity can be found at:
http://www.pnsn.org/SISTERS/welcome.html
Information contacts:
U.S. Geological Survey-Cascades Volcano Observatory, Vancouver, Washington
[phone]
Pacific Northwest Seismograph Network, University of Washington, Seattle, Washington
[phone]



This is file /SEIS/PNSN/NEWS/pressrelease.html
general format last modified 05/15/03

[livetohike]

1. Interesting

and what a beautiful area of the country. Thanks for posting this. We have an old friend in Bend.

[happyslug]

2. Test

[IndianaGreen]

3. "a modest volume of magma"

The processes that have been causing the uplift over the past seven years could eventually lead to shallower intrusion of magma or even to a volcanic eruption; however, both are unlikely without significantly more intense precursory activity. Scientists continue to monitor the situation closely and to evaluate data from field instruments.

They showed a segment in the news a couple of days ago about increased magma activity in another place, Yellowstone. Looks like the entire region is becoming geologically active again.

Picture of the Three Sisters:

[gkdmaths]

4. its never been inactive.

its amazing that most of us in the region can go about our lives without ever realizing it, but once youre there and you pay attention (and you have the knowledge) you realize that there is a great deal of geological activity happening before your eyes.

someties it becomes surreal.

For instance, I once observed a Red Admiral avoid a small plume of H2S emitted from a vent at ~11,000 ft on Mt Adams.

gkd

[Ediacara]

5. More magmatic hysteria....

Well it should all work out ok since subduction zones don't actually exist, and well, ya, then I guess geology doesn't work anymore.....

In any case, the USGS will make a big deal about an eruption that's actually iminent. They knew about St Helens with primative equipment and poor prediction techniques, and now, you will can be assured that a Cascades eruption would be prefaced by the same sort of evacuations and eruption predictions.

In any case, you still have plenty of time to buy homeowners insurance...