Re: Volcano Questions

William Oertell wrote:
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Magma feeding the volcano's magma chamber comes from the highly
pressurized outer core, which is a liquid composed of metals and reduced
silicon. The pressure is resultant of the burden above the outer core
and
the force of gravity, I believe. Pressure acts in 360 degrees, so the
liquid material in the outer core will find the point of least
resistance,
and begin to migrate out of the outer core towards the surface. When it
erupts onto the surface of either a continental plate or a oceanic
plate,
it becomes a volcano, spitting out lava. The process of the magma
making
it's way towards the surface along conduits like faults, fissures, etc.
will cause tectonic activity, by the magma placing force on existing
plates/structures already in some stressful situation, due to existing
tectonic activity. This results in earthquakes, which is why
earthquakes
or seismic events proceed most (if not all) volcanic eruptions.



Not all volcanoes explode onto the surface, some just ooze or flow out,
after breaking through the surface. Some blow a small chunk of the
mountain away and then just flow lava down the sides of the mountain.
What causes a volcano to explode in a massive, violent eruption, sending
million of tons of debris into the air? Does magma build up in a
chamber
(magma chamber) until some event triggers a explosive eruption?



And further, it appears to me that as billions of cubic feet of magma
are
discharged from the outer core, that those continental and oceanic
crusts
being assimilated into the mantle would in turn cause some of the mantle
to be assimilated into the outer core, since there must be a material
balance, mass is not being created in the core, and it is not a empty
hole
after discharging magma. I would think the material balance of the
outer
core has remained relatively the same for most of the 4.7 billion years
the planet has been here, which means something must replace what is
belched out in volcanoes over the years. Gravity would tend to cause
the
dense metals (nickel, iron cobalt, etc.) to be drawn into the outer
core,
along with other material "along for the ride".


After looking at the USGS map of volcanoes in the western US, they all
line
up in a line parallel to the pacific coast and the pacific plate, where it
interacts with the oceanic plate. I suppose conventional volcano theory
would explain why there are no volcanoes in Kansas.

Has any volcano been found away from interacting plate zones (difficult to
explain using the conventional theories)? For instance in someplace like
Kansas where the nearest plate is on the dinner table, or perhaps on the
seafloor, nowhere near interacting plates?

Let's not forget Hawaii and Yellowstone.



OK -- time to hijack thread.

I've noted that Yellowstone, Long Valley, Valles, Fish Canyon Tuff/La Garita, San Juan Mountains, etc, are all examples of humongous volcanic systems that have not been associated with continental subduction. I've gotten a kick out of simply trying to identify some of these features using "Google Earth."

One such system is between Butte and Helena, MT. When playing with Google Earth, I noticed a large oval feature roughly 150mi x 250 mi, that is bounded by the Big Belt Mountains, Beaverhead and Sapphire Mountains (next to Bitteroots), with long axis running from Missoula through Butte down to Yellowstone. If you back up to about 600mi on the display, you see the oval quite clearly -- it fills up the whole sw corner of Montana. The shape seems to strongly suggest an oval, but its orogeny may not all be volcanic -- I'm curious if anybody can explain this to me?

Dan
.