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Sisters volcano bulging...more equipment brought in

While the press pooh-pooh's the bulging found in the South Sister volcano..USGS is setting up more equipment to monitor the build up of gases...Remember the silence around Mt. St. Helens and read on...

Sister develops tell-tale bulge

After 1500 years of quiet an Oregon volcano threatens to blow.

22 May 2002 TOM CLARKE The South Sister volcano, near the town of Bend, Oregon. USGS

An ominous bulge on a dormant volcano in Oregon, accompanied by the faint whiff of magma from deep within the Earth, suggests that the mountain is rousing itself from a 1,500-year slumber.

It is unlikely that the peak, called South Sister, will blow in the immediate future, say vulcanologists on the ground. All the same, they are stepping up efforts to monitor the volcano and to predict how an eruption might affect the town of Bend in central Oregon, just 22 miles away.

"About one in ten such cases might culminates in an eruption," says Clive Oppenheimer, a volcano researcher at the University of Cambridge, UK. The groundswell may be the beginning of an awakening that takes decades or centuries, he says.

Ground swell

The bulge was first spotted last year in satellite images of the Three Sisters chain of peaks. Returning to archive images, scientists working for the US Geological Survey (USGS) determined that the bulge first arose in 1996 and has grown about three centimetres a year since. It is now 13 centimetres high and covers about 100 square kilometres on the western flank of the volcano. Compared to the 100-metre-high bulge that preceded the devastating eruption of neighbouring Mount St Helens, South Sister's hump is modest to say the least. But, says Oppenheimer, it covers a vast area, so the magma movement that is causing it "must be very big".

South Sister's groundswell ringed by contour lines. "We're now tracking its growth," says USGS volcanologist Charles Wicks, based in Menlo Park, California. He and his colleagues have installed global-positioning system (GPS) and seismic monitoring instruments at the centre of the bulge. The GPS device measures changes in height and position to within millimetres, confirming that the bulge is continuing to rise.

What looks like volcanic activity smells like it too. Sensitive molecular detectors are picking up changes in the levels of chlorine and sulphur ions in spring water coming from the mountain and the type of helium gas seeping from rocks. The signatures are characteristic of new magma, suggesting that it is rising from deep within the Earth beneath South Sister. But geologists believe that an eruption is a way off, because both carbon dioxide in the air and seismic rumblings are noticeably absent.

Volcanoes typically start to release CO2 when magma is close to the surface. Also, the rumblings and small earthquakes that always precede eruptions can only occur when the existing rock cracks to let magma through.

Keeping watch

The only way to establish if and when South Sister will erupt is to keep watching, says Wicks. The magma is still about 4 miles deep and not yet breaking through rock, so "anything could happen anywhere", he says. If it blew, South Sister could put on quite a show. The Three Sisters are composite volcanoes. Other composites include Vesuvius in Italy, Mount Fuji in Japan and Mount St Helens, just north of the Sisters in Washington state, which have all erupted with devastating consequences.

The wilderness around Bend is becoming increasingly settled. Some 110,000 people live in areas that were criss-crossed by rivers of hot ash and rubble in previous Three Sister eruptions. Based on the early evidence, the USGS is drawing up an emergency-response plan. It details which areas may be most at risk and how best to evacuate the area if South Sister were to wake from her slumber.

homepage: homepage: http://www.nature.com/nsu/020520/020520-5.html

Neat article, silly commentary 06.Jun.2002 10:17

it's not if, it's when

The High Cascades are volcanoes. They are considered "active" geologically, not in "slumber" as the author would have.

There is no reason to believe that the active volcanoes of the Cascades (Hood, St. Helens, Adams, Rainier, Three Sisters, others...) won't erupt again. The tectonic forces that drive this volcanism are ongoing, thus the volcanism will be.

There is no conspiracy of silence on the part of the scientific community about this. These mountains will erupt. The nature, size, and timing of the eruptions however is highly unpredictable.

What is a composite cone? 06.Jun.2002 10:56

Volcano lover

The volcanoes of the High Cascades are composite cones - they are built up by successive eruptions. Each individual eruption will differ: some will primarily be lava, while others will be ash and debris. Some will be relatively small, while others can be quite large and even destructive.
What is a composite cone?
What is a composite cone?

On the more destructive end... 06.Jun.2002 11:01

Volcano lover

Sometimes eruptions will result in the destruction, rather than the building up, of a composite cone volcano... such was the case with Mt. St. Helens in 1980.
On the more destructive end...
On the more destructive end...

No conspiracy- just science vs the community 06.Jun.2002 11:05


I agree there is probably no conspiracy. But I don't agree that somethings important to the community will be kept quiet.

I live next to Mt. St Helens during it's eruption. I lived in a rural area and I felt small earthquakes and observed changes in my well water the year before the eruption. When I contacted the USGS and other agencies I was told that the agencies did not observe this phenomena so it did not exist. I invited these scientist to take water and gas samples from my well. That never happened. I was shamed in the local press after I wrote letters to the editor. Finally, I had so many calls after my letter to the editor I organized a group of people in the area to call me when they experienced earthquakes, ground water or well water changes or other phenomena. I documented hundreds of occurences and took them to the USGS who continued to say that the there would probably be no eruption in the near future...this was just normal Cascade Mountain behavior.

What scientist have not done well is to be good social workers, good communicators and in many ways good qualitative researchers. If this lady in Sisters has observations to share...I would suggest that she start organizing on a local community level, go to the USGS as a coaliton, and if they still refuse to hear...start their own investigative research team.

Private wells are a good place to start. Does the water taste or smell different? Earth movements: string dangling ornaments with small bells. Keep a log. whenever the bell rings...chart it. Share this information with other community members. See if other people are experiencing this phenomena. Educate yourselves. We did not have the internet to help educate us in 1980.

Report back to this website if you have concerns.

Just because people don't hold a degree in science does not mean they aren't smart. Academic eliteism is a social disease.

Most destructive 06.Jun.2002 11:12

Volcano lover

Oregon's lovely Crater Lake is a caldera - the hollowed out remains of a once-massive volcano, similar to Mt. Hood etc, known as Mt. Mazama. It blew its insides out around 7,700 years ago, and the remaining shell collapsed in on itself, forming todays "crater".

Needless to say, this sort of eruption can happen in the Cascades, and were it to happen near a populated area could kill lots of people. This is not a secret, and anyone who lives near the Cascades should be aware of this fact.
Most destructive
Most destructive

Willamette Valley could be target 06.Jun.2002 14:20


The swelling on the South Sisters is on the west side. If the the mountain blew the hot gases and ash would most probably shoot toward the Willamette Valley... Eugene, Corvallis, Salem would be in it's path. Eugene, especially.

Tectonic plate tilt. 03.Oct.2004 22:52

Bryan York yorkbryan@hotmail.com

My observations in Washingtons Geology, is Tectonic plate tilt will cause mass sudden land drop. I see this evidence in the area of the L.C.Formation and South west quadrant. Earthquakes and sulfer emissions will be on the rise. Animals will be acting odd and minor faults will be post indicators of events that are imminent. Volcanic activity just the byproduct of events now occuring. Bryan York. www.bryanyork.com