With the recent postings concerning the Yellowstone SuperCaldera, I got to ruminating about the properties of lava and what some of the mechanisms of an eruption (especially in supercalderas) could be. I have never studied volcanism, so my thoughts on this are from a working experience with thixotropic Non-Newtonian fluids, which pretty much defines magma.

First I’ll define some terms:

A Newtonian fluid is any fluid which has a linear relationship between its shear stress and velocity gradient.

A Non-Newtonian fluid is any fluid which DOESN’T have a linear relationship between its shear stress and velocity gradient. There are different classifications of Non-Newtonian fluids based on the reaction of the shear stress to increasing shear straing (velocity gradient). There are Plastics, Dilatants and Thixotropic.

Since magma is thixotropic we will center on this class of fluids.

A thixotropic fluid is one that requires some finite amount of shear prior to flowing (it has a yield point basically). The best example of this is toothpaste. Toothpaste, if a sufficient shear force is not applied, remains in a “gel” form and can suspend an object (i.e. it can resist a shear force). Once the required shear force is applied to break the “gel strength” the toothpaste then transitions from a “gel” to a flowable “fluid”. (Ketchup is another good example.) A flowable fluid cannot support a shear force. As long as the thixotropic fluid is flowing, it will remain in the “fluid” form. But the minute it comes to a stop, it begins to transition back to the gel form, which means its viscosity (resistance to flow) dramatically increases and you are back to the “required shear force” to get it to move again. These fluids are also known as “shear-thinning” fluids.

Now we must drill down to a smaller subclass of thixotropic fluids in order to get where magma belongs. Not only is it thixotropic, but it can also transition completely to a solid depending on its temperature and pressure. Materials that fall into this category are cement (this is chemically dependent instead of just temperature and pressure dependent), molten metal, and magma.

This subclass is very important to what I theorize could happen in a supercaldera. Because it is the gel transition phase to a solid that is the important thing. During this transition time a problem referred to as gas migration can take place. This problem is battled in any industry that works with these type fluids. For instance, the casting industry goes to great pains to avoid “worm holes” that gas migration can cause during the gel-to-solid transition time in metal castings. The oil industry is constantly striving to combat “channeling” that can occur in the cement sheath when a gas producing zone begins to migrate during the gel-to-solid transition time.

So why is the gel-to-solid transition phase so critical?

Let’s say we have a tall, tall pipe, standing vertical, sealed at the bottom and open at the top. We drill a small hole in the side of the pipe and start pumping high pressure gas into this hole. The gas will rise up through the pipe and exit out the top. Now, let’s stop pumping the high pressure gas for a little bit and instead pump a cement slurry in the top of the pipe. Once we have the pipe full, we begin pumping the high pressure gas back in near the bottom. The column of cement (which right now is still a fluid) creates a hydrostatic head (pressure) at the bottom of the column dependent on the height of the column. If our column of cement is tall enough (which we are assuming it is) it will have enough hydrostatic pressure to restrict the gas from flowing upwards.

Now, move forward in time a bit and we get to the gel-to-solid transition time of the cement. We still have our high-pressure gas acting at the bottom of the cement column. But what is happening now is, the cement slurry is in the process of converting to concrete, and isn’t quite there yet. It is a gel, with a limited gel strength (like our toothpaste). When the cement hits the gel-transition phase, it no longer acts as a fluid, and it no longer can produce hydrostatic pressure at the bottom of the column. Hence, our high pressure gas now can “channel” through this gelled cement because it has enough energy to overcome the gel strength.

Now, in my mind, this channeling is the exact same phenomena that creates volcanoes in the first place. Earth was a big ball of hot stuff in various forms that coalesced and began to cool…from the outside in. So the outermost layer cooled first but the molten layer below continue to outgas. Before the outer layer could solidify (during its gel state) the molten layer below “channeled” and then (over large periods of time) continue to move since it was still fluid…but left its little blow-hole behind in the outer layers.

Now getting to supercalderas, such as that in Yellowstone. We have this massive stream of magma coming up and building pressure through outgassing and such. If this stream of magma is “mushrooming” over a large space, then the surface area of molten magma contacting the cooler upper crust is increasing and this will dramatically increase the cooling rate of the top part of the mushroom. If this mushroom top begins a gel-to-solid transition, it can then no longer hold back the outgassing occurring below, and you’d get a “kick”, or a blow-out.

Am I not correct that part of the concerns here lately are that the heat is rising in an ever-widening area in Yellowstone? Is this a sign that the magma is mushrooming out? Could we be seeing the signs that the mushroom cap is becoming large enough to start cooling and entering the gel-to-solid transition?

I look forward to any and all inputs concerning my thoughts.

Interesting. Can't really comment much on it since my education neglected fluid dynamics and I'm more of a volcano tourist than geologist.

I do know that the composition of the magma has some effect on the way the lava emerges.

A lot of the effects will depend on what type of volcanic activity develops. I'm not sure if these volcanos tended to be shield volcanos or the more common strombolian volcanos. And I can't recall offhand what happened last (geologic) time.

Hmm.

Perhaps what we need are some links to volcanism research on the region?

I know! (Please do respond though!!!)

Did you notice my post on the WWS thread? There has been a 4.4 in West Yellowstone!

I know! (Please do respond though!!!)

Did you notice my post on the WWS thread? There has been a 4.4 in West Yellowstone!

Yeah I saw that. I want to bring the GPS data into your discussion but it might take me awhile to think through.

kukla, are you refering to the use of GPS to track land mass movements? I have been doing a little of that over the last 3 years but only with landslides and settlement creep. I know they are now using it to monitor fault movements in California. You have to get to survey grade equipment to detect that sort of thing and plot velocity vectors.

However, the use of mapping grade equipment and a good GIS like ArcGIS would allow a visual comparison for the area of the caldera in relation to temp changes. I'm certain the USGS is already utilizing this to aid in their understanding and research of this sight.

Thank you very much, Kukla. Your theory makes good sense to me.

Yes, as the magma transforms it will decrease in volume and in mass (due to outgassing, fluids loss, etc.). This volumetric loss during transition is the very culprit that disallows the solidying thixotropic fluid from maintaining the hydrostatic required to "hold back" pressure that may be pushing up underneath it. So, if the magma is mushrooming out radially, it would not surprise me if there was subsidence if it were beginning to transition.

Thanks again!

[Edited on 21-8-2003 by Valhall]

Bumping for the sake of the times.

S+F
Wonderful thread Valhall,
Good to see you back on the boards more on this topic to.

Thanks indeed for the information and explanation of the dynamics of the lava during the phase transitions.

A thought as the locality of the current swarm.

So if we assume such a mushroom has indeed since when you posted this and to now been growing of lava in the caldera.

Now in addition to the normal cooling of the top of the Magma/Mushroom by convection and such like, I have been thinking on something about the recent events a bit.

It would appear to me due to the nature of the swarm, the proximity and depth, and the historical characteristics of this immediate area that a Hydrological Event is taking place. Either more water is being added to the current hydrological nature beneath the lake, or one of the current flows of such has been blocked, and therefore is working itself a new channel back out.

Hopefully so anyhow!

Now only recently as I am sure you know was the lake really explored properly, and the amount of Hydrothermal Vents really surprised many researchers.

So we know there is a lot of activity, lots of water circulating down, being heated and returning again to the surface on the lake floor, and surrounding areas, as a norm.

If the current events are just as hoped and speculated by myself just a blockage, or new channel, vents, geyser being formed, all the seismic activity by the pressure of such steam/water just on top of the caldera has me worried that it may allow a new fracture of the plume/caldera solid top in the lake, allowing a huge amount of new water to literally drop suddenly onto the "mushroom" head from the lake.

That would I assume rapidly change the temperature of the top part of the mushroom, and create a further transistion as you describe, from convection magma properties of the system, to the gel like shift you mention.

Further blocking any normal and natural convection, movement of the magma, Capping it as such as you describe, allowing further pressure to build from below?

Your thoughts greatly appreciated.

Kind Regards,

Elf.

Yeah, you know, the docudrama that was produced a couple of years ago on a Yellowstone eruption centered in on hydrologic activity causing a destabilization of the magma cap and column. In that scenario an earthquake caused a fissure, IIRC, that allowed the water from the lake to invade down into the magma chamber creating superheated steam that basically caused the big blow in a localized area. Once you get an eruption in one localized area (which would release the containing pressure, then the destabilization grows in area and it becomes a chain reaction. In the docudrama it required a minimum number of localized eruptions before the entire supercaldera became unstable enough to erupt as a whole unit.

This, of course, all makes sense.

If you had water (snow melt, whatever) invading the magma chamber and impinging on the magma cap you would have kind of a one-two punch, so to speak. First, you're cooling the top of the cap, which hastens the gel transitioning, and second you're building up one hell of a steam head that is wanting to escape (with basically the only way to escape being upward). So if the pressure from the steam caused an eruption that released the steam pressure, then what you've got is a cooled cap that can't transfer hydrostatic pressure to the magma column below it.

icky combination.

Originally posted by MischeviousElf

have been digging around really wanted to read it again and bring to ATS the info.

Thanks Indeed.

Elf.

The "Worldwide Event" thread which was basically the first "Quake Watch" thread in 2003 is what brought me to ATS. I've watched global quake activity since the 90's, and up until I got fed up with the nonsense here, I kept a running track of annual activity categorized by magnitude.

Anybody who argues against connectivity in global quake activity is a goober that hasn't spent time looking into it. When the Boxing Day quake happened in Indonesia it rippled water in wells in America. That kills any argument that the energy from one quake can't affect the status of another fault area - any where on the globe. But, also, in tracking this over the years, others and myself, have seen a pattern of activity in a particular area being followed by activity in a specific other area....like they are coupled by some means - whether it just be the default travel of the energy wave to that particular location, or whether they have some connectivity due to magma flows, etc.

Also, I'd like to add something else in here. Back in 2004 I did an ATSNN Exclusive Interview with the lead scientist at Yellowstone because there were rumors rampant across the internet that noxious gases were being released and that bison had been found dead, etc.

I have asked the moderators to see if they can find that interview. And this is why it's important....

In the interview I was outright lied to. I was explicitly told that no unexplained animal deaths, or animal deaths associated with gaseous emissions had taken place.

So we rocked along here believing that we had set the record straight and that all the panicky rumors that were running about were just dooms day bull-hockey....That is until the docudrama came out and it was accompanied by a documentary in which the geologists/scientists at Yellowstone were interviewed - the rumors of the bison being killed by dangerous gases that had emitted and lingered at ground level due to the cold temperatures had been true (I believe it was like 5 or 6 bison dropped dead all at the same time because they grazed into the area where the gases had collected), and they had taken place prior to my interview...so I was outright lied to.

Lesson to pass on is this - your tax dollars that pay the USGS scientists don't necessarily buy you the truth. So, take that for what it's worth.

Val, in a general sense, could you give us your take on this recent swarm activity at Yellowstone? Where does it all fit in? Do you feel these quakes are caused from hydrothermal or geothermal activity, or both? And why in your opinion is the USGS justified at this point in not raising the alert level? Or do you feel otherwise?

I don't remember seeing you giving an overall opinion on these quakes, but forgive if I missed it.

Originally posted by TrueAmerican
Val, in a general sense, could you give us your take on this recent swarm activity at Yellowstone? Where does it all fit in? Do you feel these quakes are caused from hydrothermal or geothermal activity, or both? And why in your opinion is the USGS justified at this point in not raising the alert level? Or do you feel otherwise?

I don't remember seeing you giving an overall opinion on these quakes, but forgive if I missed it.

I have only tenuously kept up with the fast-moving thread so I'm unclear on what all the data is. Has the lake level decreased in any stepwise fashion since this started? Are there any unexplainable short-term water level decreases in the area where the increased activity is occurring? While I have not paid enough attention to the data to even proffer a guess on what could be happening, the sticky-wicket about Yellowstone is that it could be both. Anytime the hydrothermal situation becomes unstable and kicks, it could open a fissure and then you've got the combo deal going.

The current activity mirrors that of the 2003-2004 period, only I believe the "swarm" that is occurring has a higher number of quakes involved in a short amount time than during the last period of increased activity. I can tell you this, that the one USGS update that took place a couple or three days ago where they stated this is "not business as usual" and that DHS was reviewing evacuation plans for the two neighboring counties is not something I've seen come from the USGS before concerning Yellowstone activity in the past. So that was a bit disturbing to see, but at the same time a little more comforting than their behavior in the past. At least they have started acting as they should - i.e. anytime Yellowstone kicks a fit it's something to take serious.

Originally posted by Valhall
The Baker activity is interesting in light of the recent Yellowstone activity.

Yes I thought soo but the snow came in, and we didnt manage to get a Full 360degree and Aerial View so it sort of petered out.

I did try very hard indeed many emails, great effort by some members... it seems they wont Lie now just ignore you totally.

To think the thread I posted this in response too, I was only saying in there initially before giving the OP the benefit of the doubt, Yellowstone has been quite not active recently, lol.

Then a couple of weeks later Bam.

It is though now you mention it very telling especially as the observatories own website seems to be down.

Thanks for the Old reserach and Cascades info will look into it now Valhall.

You have put a lot of really good research and effort into ATS, and I know maybe you feel things were not as they should be, but it is very much appreciated as a community, is there for prosperity and thanks for sharing it with us, and bringing this back up so we can compare historically what's been happening There.

I am wondering now if the 11th full moon which I think is the 4th closest? for many years is going to trigger anymore activity, especially if any not very viscous at all.

Thanks again Valhall, for the info, and meaning ive got many pages of reading to do late in the UK because wont sleep till I have read it lol.

Kind regards,

Elf