[Geysers] North Goggle Description

[Michael Goldberg]

David,

No, you haven't missed anything that I'm aware of.

This might be a good opportunity to remember some details of North 
Goggle's other recent active periods.  What Graham saw falls nicely in 
line with I recall from the 1990s.

[Facts and figures in the description below may be incorrect. 
Corrections are welcomed.]

Back then the intermittent overflow periods came regularly every 11 
minutes.  The first precursor to eruptions was an "extended" overflow that 
lasted well beyond the usual 2 minutes.  For as long as the water level 
stayed up North Goggle (and Goggles Spring) would get progressively 
hotter.  It took a half-hour or more to reach the point where there was 
any kind of boiling at the surface.  Usually the water drained too soon, 
and the moment of opporutnity was lost.

After a lengthy extended overflow, say an hour or more, the water would 
drain down and boil/splash furiously at depth.  The recovery time varied 
in correspondence with the duration of overflow.  In any case, boiling 
died down as water reappeared and rose slowly in the vent.

Then upon reaching overflow there would be a flood of large (i.e. 
filling the entire vent) bubbles. This would either trigger a minor 
eruption, or not.  If not, the next couple of overflow periods would 
start in the same way and could also bring about an eruption.

Minor Eruptions had heavy water to 6-10 feet and lasted maybe 20 seconds.

I'm a little fuzzier on what happened after the eruption.
In many ways it was like the recovery following an extended overflow.
One difference: The first subsequent high-water period (20 minutes 
post-erutpion?) would stay well below ground.  The ones after that would 
be as described above and could again trigger an eruption.

When North Goggle had series of minors, the most common interval between 
eruptions was 40-60 minutes, so it would go again on its second or third 
chance.  The number of eruptions in a series roughly paralleled Grand's 
burst count at the time -- mostly 1 to 4, but capabale of throwing in a 9
just to keep everybody off balance.

I never witnessed a major eruption.  My understanding is that tthe 
extended overflow continues for long enough that the system heats up to 
the point where it can launch straight into the eruption.

Timing: The events described often started around the end of a Lion 
series, with the eruptions occurring during Lion's quiet period.

The 1985 activity was apparently quite different.  Most eruptions were 
majors, and most of them occurred within a Lion series [see Allan 
Friedman's article in Transactions I].  I don't know anything about the 
precursor activity that year.

Michael Goldberg
Michael.Goldberg at uc.edu