On Wed, 14 Sep 2005 18:22:38 -0400, Bill Alliston
wrote:

Must be some kind of sensor that can spot a 28 mm movement. Of course my wife can get a
headache before I can raise half that distance. ..... It said OT!


The state of the art today in such mesurements is around .5 mm over 20
miles. They use lasers among other things. Some fascinating stuff. I
live within 5 miles of the San Andreas Fault, and about 40-60 miles as
the crow flies from Parkfield, California, the most active place in
the US. Ive taken the tours etc. Really interesting stuff.

Gunner


Gunner Asch wrote:

http://www.livescience.com/forcesofn...ers_bulge.html


Mystery Bulge in Oregon Still Growing
By The Associated Press

posted: 06 September 2005
09:02 am ET


BEND, Ore. (AP) -- A recent survey of a bulge that covers about 100
square miles near the South Sister indicates the area is still growing,
suggesting it could be another volcano in the making or a major shift
of molten rock under the center of the Cascade Range.

Recent eruptions at nearby Mount St. Helens in Washington state have
rekindled interest in the annual Sisters survey and its findings.

Oregon has four of the 18 most active volcanoes in the nation -- Mount
Hood, Crater Lake, Newberry and South Sister. A recent U.S. Geological
Survey report said monitoring is inadequate at all of them, with only
basic monitoring at about half of the active volcanoes.

Unlike the volcanoes, the bulge gets an extensive annual survey to
track its growth. Spread out across an area nearly as big as the city
of Portland, It's centered about three miles southwest of the South
Sister, about 25 miles from Bend.

The results of the late August survey won't be ready for weeks, but
scientists have reached some conclusions about the bulge from past
monitoring.

They say it probably began growing in 1997 and has been rising ever
since at a rate of about 1.4 inches a year. It was first observed from
space using a relatively new imaging technology known as radar
interferometry that can measure changes in the Earth's surface.

The likely cause of the bulge is a pool of magma that, according to
Deschutes National Forest geologist Larry Chitwood, is equal in size to
a lake 1 mile across and 65 feet deep.

The magma lake is rising 10 feet each year, under tremendous pressure,
and it deforms the Earth's surface as it expands, causing the bulge.

Other causes could be anything from the birth of a new volcano -- a
fourth Sister in the making -- to a routine and anticlimactic pooling
of liquid rock, researchers say.

"The honest and shortest answer is, we don't know,'' said Dan Dzurisin,
a USGS geologist.

Dzurisin recently led a three-person leveling crew on a slow walk
across the top of the bulge. They were hoping to detect any change in
its surface using survey equipment accurate to one-sixteenth of an inch
for every mile measured.

Dzurisin's survey data, in concert with space imaging and satellite
positioning measurements from two dozen fixed points on the bulge, give
scientists an idea of the bulge's depth and size.

Additional information from seismographs and chemical monitoring of
area springs reveal movement of the magma underground. A swarm of 350
small earthquakes in March 2004 indicated magma was on the move, but
the bulge has been quiet ever since.

Whether the magma will move again or ever reach the surface is a
mystery. But if it did, geological history suggests it would result
only in small cinder cones that spew ash and lava.

The good news is that such an eruption likely would not seriously
affect any population centers, Chitwood said.

Such cones are the most common volcanic features on Earth, he added.
Central Oregon has about 600. Basalt flows have occurred in the area of
the bulge every 1,000 to 1,500 years for the past 4,000 years, he said.
And the area is due for another.

"The bulge is on time,'' Chitwood said. "The bus has arrived.''

end


This makes sense. The ring of fire around the Pacific Ocean, has gaps,
of activity, between Mt St. Helens, and Mexico City. I am expecting the
Long Valley Caldera to become active, within a few million years, but
also, the area of Mojave VAlley, CA, and the Colorado River area near
Las Vegas, and also Pheonix,AZ.

How do I get to this? If you locate the subduction zone along the
Washington - Oregon coast line, then measure the distance to the
volcanoes Mt. Baker, Mt. Rainer, M. St. Helens, etc. (See:
http://vulcan.wr.usgs.gov/Volcanoes/...ade_range.html)

Now find the San Andreas Fault in California, then measure the same
distance, to the east and draw a line parallel to the SAF, and you get
the general location of possible volcanic activity in the future.

AS the Pacicfic tectonic plate subducts beneath the American plate, the
material of the Pacific plate is forced down and into the molten magma
inside the Earth. This material is lighter(lower specific gravity) than
the magma, and it coagulates and floats upward. Eventually you have
volcanic activity, at or near the surface.

Got volcano insurance?

Gunner

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner