[Geysers] Geyser Report June 13 (Stephens)

[Lynn Stephens]

I don't have anything as exciting as Giant video or Ledge or Norris 
disturbance--so I'll just do some "facts" on Great Fountain for today's 
report.

Since the road opened on May 26, I've oberved 27 closed intervals ranging 
from a minimum of 10h11m to a maximum of 18h26m with a median of 12h15m and 
a mean of 12h32m.  I've recorded 21 overflow lengths ranging from a minimum 
of 72 minutes to a maximum of 102 minutes with a median of 81 minutes and a 
mean of 83 minutes.  To get the "half hour" prediction I'm generally using 
70 to 100 minutes, but adjusting so the prediction is to the nearest "5" or 
"0" minutes.  I've generally been having good results adjusting the midpoint 
of the 4 hour prediction window based on the number and strength of the 
bursts.
     No fourth or very weak fourth with long pause between third and fourth 
--10 1/2 hours
     Strong fourth with no fifth -- 11 hours
     Strong fourth with medium fifth -- 12 1/4 hours
     Fifth with no sixth or weak sixth -- 13 hours
     Six with no energy expended in the seventh -- 14 hours.
     Six with weak seventh -- 15 hours.

People have asked how to determine the end of the eruption--It's subjective 
but I've been using the definition that others studying Great Fountain had 
used before me--the end of the last burst that throws water out of the 
crater.  A regression of duration against following interval doesn't work 
quite as well as the subjective rule of thumb given above.  For example, two 
eruptions may have the same duration but if one had longer than average 
pauses between, for example, the third and fourth bursts and the individual 
bursts in the fourth are separated by many seconds and the bursts don't 
throw out much water, then that eruption will result in a shorter subsequent 
duration.

If we don't know the duration, then we are using 12 1/4 hours as the 
midpoint of the four hour prediction because the median has been staying at 
12 hours 15 minutes.

I've been asked whether a false overflow has any impact on the length of the 
subsequent "true" overflow.  I don't believe so.  I don't have a large 
sample size to quote in this email--just the three observations from this 
year, but I believe they are representative of prior years' observations. In 
one case this summer a false overflow was succeeded by a subsequent "true" 
overflow of 78 minutes (just slightly shorter than the "average" overflow), 
in another case the false overflow was succeeded by a subsequent 
"true"overflow of 85 minutes (just slightly longer than the "average" 
overflow), and in the third case, the false overflow was succeeded by a 
subsequent "true" overflow of 102 minutes (the longest "true" overflow of 
the season to date).

Weather report:  Warm and sunny.  I left the trailer this morning at 6:30 am 
carrying my sweatshirt and sweatpants to put them into hte pickup in case I 
need them tonight.

Visitor comment(s) of the day.  Greaqt Fountain was having a beautiful 
sunlit eruption that started at 10:29 this morning with almost no clouds in 
the intensely blue sky as a background. There wasn't much steam because the 
temperature was already in the mid to upper 60's.  There was just enough of 
a light breeze to blow the steam toward the northeast--in other words, 
superb viewing conditions from the boardwalk.  A father was leading his 
young son back toward the parking lot about 4 mnutes into the first burst.  
In the other hand the father was carrying a video camera.  The boy looked to 
about 6-8 years old.  As they passed me, I could hear the boy say, "But I 
want to see more of this."  The father's reply:  "We'll watch it when we get 
home."

Animal tidbits:  As I was driving from Firehole Lake toward the main road, 
there were four white pelicans performing their aerial ballets in the sky 
above Fountain Paintpots.  I'm always surprised to see the black tips on the 
underside of their outstretched wings, which make the twists and turns and 
loops and circles in their flight patterns easily distinguishable.

I was talking with some visitors at Great Fountain this morning.  They are 
camped at Mammoth, close to two college age girls from an Ivy league 
institution who were camped with a dome tent.  This morning the woman was up 
early to use the facilities and noticed a cow elk approaching the dome tent. 
  At first the cow elk sniffed around it for awhile.  Then she started 
rubbing her nose on the tent.  And then she started chomping on the tent.  
At some point the two girls woke up.  One of them was apparently VERY afraid 
of bears.  So one girl was hitting at the tent wall while the other girl was 
screaming "No, don't, you might antagonize it."  The woman watching the 
scene yelled over that it was "only" an elk, not a bear, so it was OK to try 
to scare it off, or, if they wanted, it was OK to come on out of the tent 
since the elk probably wasn't going to eat on them.

Lynn Stephens

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