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Seeing as how neither you nor I were in this group back when I first read this article:

http://news.nationalgeographic.com/news/2011/01/110119-yellowstone-park-supervolcano-eruption-magma-science/

Basically it is an article on the "deep breath" the Yellowstone Caldera took recently. I know you are studying to be a vulcanologist, so I'm pretty sure you guys have talked about this in class. I would be very interested in what you have to say on the matter.

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warming up for 2012 baby! just like in the movie!

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Most of the time we spend talking about calderas focused on Long Valley Caldera in eastern California (the second largest volcano in N. America, rivaled only by Yellowstone) due to its proximity to Fresno (~40-50 miles by air, the river that runs through Fresno originates from the western flank of this 'super volcano'.  From reading the Nat Geo article, it sounds like the uplift was probably caused by inflation of the resurgent dome by an influx of magma into the reservoir.  This could also explain the earth quake swarms, which can originate from the magma (very hot -often greater than 900ºC- viscous fluid/mush under incredible pressure) causing the country rock (the solid rock its intruding into as it rises) to thermally deform and crack, which releases energy (ie magmagenic the earthquake).  As the magma forces its way into the crack it begins to wedge the crevice in the country rock apart, causing additional earthquakes that add to gether to produce the 'earthquake swarm.'  I'm not familiar with the model put forth for episodic inflation/subsidence of the resurgent dome at Yellowstone, but I'll try to do a literature review tonight and give you a more intelligent response.

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Originally Posted by Bryant Platt:
viscous fluid/mush under incredible pressure

i thought the article said it was hot rock type lava/magma under yellowstone.

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Originally Posted by Dødherre Mørktre:

Originally Posted by Bryant Platt:
viscous fluid/mush under incredible pressure

i thought the article said it was hot rock type lava/magma under yellowstone.

Yes it did.  When you heat up a rock to extreme temperatures (these are probably well over 1000º C) and apply great pressures (such as 10+ km of rock overburden) it will usually mostly melt and form a fluid more viscous (resistant to flow) than water but much, much less viscous than a solid rock.  Just picture (or look up on youtube) a basal flow running down the side of the mountain.  It flows pretty well, but not nearly as well as water.  Also, as hinted at above, you're not usually going to have 100% liquid, you'll usually have some solid minerals with high melting temperatures and some debris pulled off the conduit walls (call xenoliths, literally meaning different rock) suspended in the melted material.

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Originally Posted by Bryant Platt:
Most of the time we spend talking about calderas focused on Long Valley Caldera in eastern California (the second largest volcano in N. America, rivaled only by Yellowstone) due to its proximity to Fresno (~40-50 miles by air, the river that runs through Fresno originates from the western flank of this 'super volcano'.  From reading the Nat Geo article, it sounds like the uplift was probably caused by inflation of the resurgent dome by an influx of magma into the reservoir.  This could also explain the earth quake swarms, which can originate from the magma (very hot -often greater than 900ºC- viscous fluid/mush under incredible pressure) causing the country rock (the solid rock its intruding into as it rises) to thermally deform and crack, which releases energy (ie magmagenic the earthquake).  As the magma forces its way into the crack it begins to wedge the crevice in the country rock apart, causing additional earthquakes that add to gether to produce the 'earthquake swarm.'  I'm not familiar with the model put forth for episodic inflation/subsidence of the resurgent dome at Yellowstone, but I'll try to do a literature review tonight and give you a more intelligent response.

I wasn't even aware of the caldera  near Fresno. What is the activity level of that caldera in comparison to the one in Yellowstone??? Just how many calderas are there in North America???

I had read about these earthquake swarms before. These are usually really mild earthquakes???

From what I gather, this swelling really mean nothing as long as the magma remains far below the surface.

I wonder how oil/gas drilling just east of this caldera and the resulting fracturing affects the caldera??? Have you guys put much thought into that???

It may seem that I am asking you a bunch of questions that I myself could research, but I really get tired of filtering through apocalyptic websites while trying to find good scientific stuff. You are the only vulcanologist I know, so you get the brunt of the questions.

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Originally Posted by Mark Simmons:

Originally Posted by Bryant Platt:
Most of the time we spend talking about calderas focused on Long Valley Caldera in eastern California (the second largest volcano in N. America, rivaled only by Yellowstone) due to its proximity to Fresno (~40-50 miles by air, the river that runs through Fresno originates from the western flank of this 'super volcano'.  From reading the Nat Geo article, it sounds like the uplift was probably caused by inflation of the resurgent dome by an influx of magma into the reservoir.  This could also explain the earth quake swarms, which can originate from the magma (very hot -often greater than 900ºC- viscous fluid/mush under incredible pressure) causing the country rock (the solid rock its intruding into as it rises) to thermally deform and crack, which releases energy (ie magmagenic the earthquake).  As the magma forces its way into the crack it begins to wedge the crevice in the country rock apart, causing additional earthquakes that add to gether to produce the 'earthquake swarm.'  I'm not familiar with the model put forth for episodic inflation/subsidence of the resurgent dome at Yellowstone, but I'll try to do a literature review tonight and give you a more intelligent response.

I wasn't even aware of the caldera  near Fresno. What is the activity level of that caldera in comparison to the one in Yellowstone??? Just how many calderas are there in North America???

I had read about these earthquake swarms before. These are usually really mild earthquakes???

From what I gather, this swelling really mean nothing as long as the magma remains far below the surface.

I wonder how oil/gas drilling just east of this caldera and the resulting fracturing affects the caldera??? Have you guys put much thought into that???

It may seem that I am asking you a bunch of questions that I myself could research, but I really get tired of filtering through apocalyptic websites while trying to find good scientific stuff. You are the only vulcanologist I know, so you get the brunt of the questions.

Long Valley Caldera (LVC) is located north east of Fresno, on the far side of the Sierra Nevada.  The LVC is topographically defined by a 22 mile across depression formed by the caldera forming eruption 760,000 years ago, which initially created a 3km deep crater (which rapidly filled 2/3 of the way with erupted ash and other debris).  Volcanism at LVC predates the caldera forming eruption by at least hundreds of thousands of years.  After the caldera forming eruption, volcanic events have persisted up to modern times (I believe the youngest eruption in the area is ~600 yrs old), however the younger events have been considerably less violent.  In the 1980's there was a flare up of activity that suggested a threat of eruption in the near future.  The resurgent dome began being rapidly inflated and large volumes of CO2 created a large tree kill in the Mammoth Mountain area on the west margin of caldera (if your into skiing you may know the name, Mammoth Mountain is one of the more popular ski resorts in California).  Several swarms of small earthquakes were also recorded and believed to denote the movement of magma at fairly shallow depth.  This increase in magmagenic activity triggered a change in the monitoring level by the United States Geological Survey (USGS) Long Valley Volcanic Observatory (LVO) staff, which designates changes in monitoring techniques dependent on degree of activity.  The media misconstrued this change in monitoring level as a sign that an eruption was eminent and quickly caused a panic amongst the inhabitants of the town of Mammoth Lakes (a beautiful resort town located within the caldera's crater).  An eruption never occurred, the rate of earthquake swarms has decreased, but CO2 emissions continue to kill off trees in parts of the LVC and recent influx of geothermal activity has forced the Inyo National Forest to close some popular hot springs (there is a risk that the normally warm water flowing into Hot Creek from the ground could turn fatally hot or even erupt in geysers).  The USGS response coding has also been changed to be more readily understood by our more vacuous friends with communications degrees.  If you would like more information on Long Valley Caldera I'd be more than happy to field any questions to the best of my ability.  You can also learn more by visiting the USGS Long Valley Volcanic Observatory website, linked below.

http://volcanoes.usgs.gov/lvo/

Yes, these earthquakes are usually really mild.  Most of them are far too small for you to even feel.

I wouldn't expect magma movement at depth to be a huge concern to the public, but of course I would defer to the experts at the USGS.  Why does depth matter?  The deeper the magma is, the greater amount of pressure it is under due to the weight of the overlying rocks pressing down on it.  As the magma ascends toward the surface the pressure on it decreases, allowing the dissolved gasses in the magma (called volatiles) to begin to come together to formulate bubbles (or vesicles).  When this happens the vapor pressure in the magma increases, pushing back against the overburden.  If this balance tips enough, a violent eruption can result.  A good example of this would be Mt. St. Helens, where a landslide rapidly reduced the pressure from overburden, allowing gasses to expand and push the remaining overburden out of the way.  So long as the magma is deep enough (read so long as pressure from overburden is great enough) vesiculation should be minimized.  I hope that wasn't too much?

I've not heard much discussion of the affect of fracking on magmatic volcanism (to discern from mud volcanoes, which can be triggered by petrol wells and fracking).  What kinds of depths are they fracturing at?  I would imagine that if one were to drill a very deep well directly above a magma chamber, if they got close enough to the magma an eruption would result (sad thing is I've actually thought about this) due to offering a low pressure (~ 1 atm if empty, the static pressure of the drilling mud if thats being employed) conduit to the surface.  That said, in several volcanically active areas (like LVC) hydrothermal energy is generated by drilling wells to collect magmatically heated fluids and use them to turn turbines.  To prevent ground water depletion many geothermal power plants re-inject fluid back into the aquifer to be reheated and reused.  I don't know of any instances of this practice of drilling and injecting fluids destabilizing the magma chamber.  Another thing I would consider is the affect of proximity to magma on the oil field.  If you have a shallow magma source you should also have a high geothermal gradient (that is, you should increase temperature rapidly as go beneath the surface of the earth).  If you have a magma chamber hanging out not too far beneath the surface things should be hot, and I'd expect you'd a) cook the oil to gas or b) burn off the gas dependent on the distance to the magma chamber and the heat of the magma.  By the fact they're drilling for oil, I'd expect they're a ways away from the magma chamber.  But this is just a slightly educated guess.

I'm glad to be of service.  I'd be more than happy to answer any further questions to the best of my abilities.

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you know, this stuff fascinates me, but i'm only versed enough to read about it lol.

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Originally Posted by Bryant Platt:

I've not heard much discussion of the affect of fracking on magmatic volcanism (to discern from mud volcanoes, which can be triggered by petrol wells and fracking).  What kinds of depths are they fracturing at?  I would imagine that if one were to drill a very deep well directly above a magma chamber, if they got close enough to the magma an eruption would result (sad thing is I've actually thought about this) due to offering a low pressure (~ 1 atm if empty, the static pressure of the drilling mud if thats being employed) conduit to the surface.  That said, in several volcanically active areas (like LVC) hydrothermal energy is generated by drilling wells to collect magmatically heated fluids and use them to turn turbines.  To prevent ground water depletion many geothermal power plants re-inject fluid back into the aquifer to be reheated and reused.  I don't know of any instances of this practice of drilling and injecting fluids destabilizing the magma chamber.  Another thing I would consider is the affect of proximity to magma on the oil field.  If you have a shallow magma source you should also have a high geothermal gradient (that is, you should increase temperature rapidly as go beneath the surface of the earth).  If you have a magma chamber hanging out not too far beneath the surface things should be hot, and I'd expect you'd a) cook the oil to gas or b) burn off the gas dependent on the distance to the magma chamber and the heat of the magma.  By the fact they're drilling for oil, I'd expect they're a ways away from the magma chamber.  But this is just a slightly educated guess.

I'm glad to be of service.  I'd be more than happy to answer any further questions to the best of my abilities.

Well fracking is either hydrological or sonic in nature (method used depends on what the rock bed makeup is). Gas wells are usually 6000 feet and deeper, but the ones that require fracking are usually at around 15000 feet. That is one of the reasons the Federal Government labeled the movie Gas Land as basically a sham......do deep to affect water wells that rarely go over 500 feet in depth (that and over half the cases shown in that film were caused by water wells running through coal beds). These wells can also be drilled to that depth vertically then take a horizontal turn for runs of over double that in length. So at 15000 feet the well should be almost 2 miles from the upper reaches of most magma pools in the Yellowstone area. Do you think disturbing the rock layers above the magma in those areas would cause unwanted results???

BTW-Damn good answers so far.