[Geysers] Re: Conduit dimensions - sources?

[Gordon Bower]

I apologize for reopening a now-ancient thread, but it seemed re-using the thread title from last October might be the easiest way to jog people's memories, and it's probably a topic of interest to a number of our subscribers.

Brian Davis mentioned, among other things: "I've been reading through Rinehart's "Geysers and Geothermal Energy", and came across a rather unusual claim - that there was a thermister measurement in Old Faithful at a depth of 175 m (!!)."

As it happens, I stumbled this week (via a different paper of Rinehart's, which claimed some very deep plumbing of Solitary also) on the 1969 paper in which Rinehart described his experience with lowering a thermistor into Old Faithful in January 1968. (If you don't have access to Journal of Geophysical Research archives and want a PDF of the whole article, feel free to contact me offlist.)

This is what he said:

"The temperatures were measured by lowering
a single thermistor by cable down the throat
of the geyser and leaving it at a fixed depth
during several eruptions. The cable was attached
to a single-channel lnstrument Corporation of
America Model 400 pen recorder operated most
of the time at a paper speed of 2.5 cm/min and
other times at 7.6 cm/min.

"The geyser tube proved to be much deeper
than the 30 meters originally anticipated, and
in the end it was believed that a measurement
was made at the extreme depth of 175 meters.
Lack of cable prevented going still deeper.

"There is some ambiguity as to the actual
depths reached. First, the geyser tube may not
stand vertical, in which case the depths quoted
here are slant depths. Second, the cable may
have been balling up at the bottom of a much
shallower tube. The apparent straight-downward
pull on the cable at all times and the general
freedom of motion were such as to convince an
experimenter that the weighted thermistor and
attached cable were freely falling at all times.
Further, the temperature patterns show progressive
changes that seem most likely associated
with changes in depth. In particular, the
pattern changed markedly between the 60- and
the 90-meter level, the range in levels at which
the sediments merge into more solid rock in the
surrounding terrain [Fenner, 1936].

"The thermistor was weighted with a modified
brass plumb bob and had a time constant of
a few seconds and a temperature resolution of
0.5øC. Simultaneous readings at several levels
were not possible with the single thermistor,
although it would have been highly desirable.
Again the great regularity of the geyser's behavior permits records taken at different times
to be meaningfully related.

"A total of twenty-eight intervals were successfully monitored: six at 15 meters, seven at
23 meters, seven at 30 meters, four at 60
meters, three at 90 meters, and one at 175 meters.

"On three or four occasions the plumb bob
was hurled from the geyser during an eruption
by the uprushing water, but most of the time
it remained below ground level, although probably
not always at the depth it had been placed."

GRB
 		 	   		  
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