[Geysers] Re: Data loggers and eruption extraction... and models

[Davis, Brian L.]

David Schwarz wrote:

> Last I was aware, they were mostly Onset HOBO loggers (and much longer
> ago, Ryan Tempmentors).

Ralph Taylor was kind enough to reply off-list; yes, the current dataloggers are evidently Onset Hobo Pro with an external temperature sensor. I'm not sure yet the resolution (in temperature), but he mentioned that he often sets them for 1 minute intervals.

> Depending on the geyser and the sensor location, it's sometimes also
> possible to get an approximate eruption duration, and even record
> non-eruptive or minor-eruptive activity (overflow and Turban cycles
> at Grand, hot periods at Giant and Fan and Mortar, etc.).

It's actually some of this "minor-eruptive" activity that I'm curious to see (which is why I need the actual data, not the reduced data). It's a shame there's not a good way to monitor the pressure within the pool, as that could be interpreted in terms of water level. There are certainly pressure sensor that have sub-centimeter water depth resolution, but they would of course need to be in the pool, which I suspect would be very hard to do and keep the Park happy about things; a very thin clear plastic tube would work, but it still might be visible, and even made of Tygon would occasionally need to be replaced. This was essentially how Old Faithful was instrumented with pressure sensors if memory serves (only the tubes went down, not the sensors themselves) for the in-conduit measurements. Pool surface temperature might actually be easy to get, in a very non-intrusive way, using an infrared thermometer from a distance.

> Detailed analysis of the data beyond extracting eruption times
> and other well-defined features therefore has a tendency to
> tell the analyst more about local weather patterns than about
> geysers.

True, although I wonder if anyone has ever done a Fourier analysis of the data to look for essentially "harmonics" in the series. For an eruption, they're going to be invisible... for a bunch of eruptions, expanded around a well-defined point, they might not be.

In some cases, some very minor variations in the model conduit give some surprisingly complex and interesting behaviors. For instance, making the upper portion of a simple conduit wide (larger diameter) made for a system that looked a lot like Turban-Grand in that there would be a quiet post-eruption phase, followed by a series of "minor" eruptions of very periodic nature, one of which ultimately resulted in a "major" eruption. This was from a single-vent model, but it's still interesting. A system that uses a "bedding plane" style geometry (a section that goes horizontal back over itself in a very small vertical distance) also has these periodic "pre-plays", but with the further interesting thing that the post-eruptive "quiet phase" is ended by a significant (but not full) eruption (restart?). I've barely touched on the plumbing variations, but I've seen how a steam bubble can turn an erupting vent into a steaming pool as well.

There are a lot of problems with these models (no cold, slow recharge as yet, convection within the conduit difficult to determine, and only one or two heat sources, always at the same depth, and only one vent so far), but there is a lot of almost eerily familiar behavior lurking in the results. I'm just not sure how relevant it is yet (but it sure is fun). 

-- 
Brian Davis