[Geysers] Blog post about geyser mechanisms

Davis, Brian L. brdavis at iusb.edu
Tue Sep 10 06:22:00 PDT 2013

Karen Webb wrote:

> Have you got a detailed description of your set-up that could be posted?

I *did* have a webpage up at one time that detailed exactly how I went about making models, generally using a hot plate, and chemistry flask with a rubber stopper, and some plumbing supplies. That page went away, and I've never put it back together.

But I really should. Do people want this?

I make mine now out of just plumbing supplies I get at Lowe's / Home Depot type stores, using the electric water heater element that the Cross's suggested to me; it works great, and is safe* and easy to make. I'll see if I can't get something formatted into a Word document or PDF. Perhaps that way the construction techniques can be spread around, and not lost every time one of us looses the file or webpage.

Ultimately... is this something we should polish up, and host on the GOSA site? The only real question to my mind is liability, and places like Instructables have far more risky (and poorer described) things on their pages...

*"Safe" meaning "as safe as you can make large quantities of boiling or even superheated water that unpredictably erupt into the air"

Carlton Cross also wrote:

> I haven't had time to locate and read the referenced sources,  but I
> think it's important to note that pressure build-up is not what causes
> an eruption.

Agreed. This is a conversation that comes up again and again it seems. I've tried to correct people on it. I've taken direct measurements and put the data on-line. There's a real conceptual blind spot it seems on this issue. The papers in question are interesting too - both (I feel) imply something, without really working it out very well. The seismic data from Old Faithful did have one interesting aspect that I felt the authors completely mis-interpreted; it showed a "flat roof" to the subsurface void they identified, which they interpreted as a flat sinter layer (if memory serves) it seems much more likely to me that this would be an upper free surface for the water layer - in other words, a non-condensible gas (not steam) bubble a the top of a chamber.

> Steam within a horizontal chamber will displace water from the
> chamber. 

Agreed, although you do have an odd issue with such a geyser prior to overflow. Steam production in a purely vertical system does not increase the pressure on the bottom of the reservoir (pressure remains constant for any given parcel of water). But for a horizontal system, steam production in the horizontal branch would actually drive pressure in the horizontal branch upwards (as it raises the water column in the vertical segment). That's probably a very important constraint to consider, as the volume of water erupted shows that even the traditionally vertical geyser in Yellowstone must have very significant horizontal reservoirs.

Thank you Carlton for a really Great description of the geyser and modeling process - you did it wonderfully, and I need to work on it some more.

Brian Davis

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