[Geysers] A Couple of Changes in the Lower Basin

[Lynn Stephens]

This morning it was rainy and overcast, so there wasn't any geyser fog as I drove in.  The cool air and lack of geyser fog made it easy to pick-up steam clouds from geyser eruptions today.
 
First, Fountain had some longer than usual intervals today.  I arrived in the Lower Basin at 6:30 am; Barbara was half an hour or so ahead of me.  I know I didn't see a Fountain steam cloud until the 1238 eruption reported by DeanL, Dauberts, and TristanP.  Assuming a half hour duration, that means any Fountain eruption had to have started before 6 am, for an interval over 6h38m.  Since Barbara didn't say anything about a Fountain steam cloud and she was at Great Fountain about 6 am, it is possible the early morning eruption started before 0530.
 
This evening's eruption started sometime after 1910 when I left White Dome and before 1916 when I had the Fountain steam cloud 1916ie as I arrived at the intersection between the main road and Firehole Lake Drive.   (Tristan subsequently posted a start of 1916), for an interval of 6h38m.  These are the first closed intervals exceeding 6 1/2 hours in quite some time.
 
Second, Gemini/Pebble changed.  On July 13 Inoted the 34 minute interval late in the afternoon.  The series of 7 eruptions that afternoon started before Pebble reached overflow, but Pebble had risen above the level of the "near" and "east" vents.  I did not make any additional observations of Gemini/Pebble on July 13.  
 
Yesterday (July 14) I noted at 0635 that Pebble was low so I drove back around to listen (it was very foggy yesterday morning) to Great Fountain erupt.  The eruption started at 0701.  Barbara went past me and I was quite surprised when she called over the radio that Gemini was ie at 0721.  I moved the pickup down to Gemini, watched two additional eruptions, saw two failed attempts, and left Gemini to go do other things.  I did not return to the area until 1345, at which time the near and far vents were both active, Gemini's runoff channel to Pebble appeared wet, and the dark ring in Pebble indicated the water level had not reached the sinter ledges above the sinter wall on the southeast side of Pebble's vent.  Over the next hour Pebble's water level crept up to the top of the sinter wall, but did not get onto the ledges.  Gemini started a series of eruptions that consisted of 8 eruptions at intervals of 6-12 minutes until there was a 14 minute interval between the sixth and seventh eruptions and an 18 minute interval between the 7th and 8th eruptions.  After watching two failed attempts, I went to watch Great Fountain and Fountain and did not return to take any additional observations.
 
At least Gemini had one clear-cut series yesterday.  Today Gemini intervals were all over the place--in minutes--8, 30, 9, 15, 35, 12, 10, 11, 18, 10, 15
2h12m, 17, 29, 11
52 m, 12, 9, 9
3h39m, 19, 12, 12
 
Between each eruption, at about 10 minute intervals, Gemini's left vent would fill, bubble, sometimes shooting marble sized drops of water 8-10 inches in the air, then drain.  Sometimes the water level in the right vent would also rise such that it was visible.
 
Over the 12 hour observation period, Pebble's water level fluctuated in concert with Gemini eruptions.  As the time for each of Gemini's eruption or fill, Pebble's water level dropped.  During an eruption, it rose as water from Gemini drained into Pebble's crater.  If Gemini didn't erupt on a fill, Pebble's water level gradually rose until time for the next Gemini fill/eruption.  This continued all day long, without any break.  Overall, Pebble's water level fluctuated from a low where part of the sinter/gravel base on the west side of the crater was exposed, to water level halfway up the sinter wall on the southeast side of the vent.  During the long (2h12m, 52m, and 3h59m) intervals between Gemini eruptions, the near vent would start rumbling, then hissing, and on the two longest intervals started spitting water.  The "far" vent in Pebble never had any activity.  The water level in Pebble never reached the base of the "near" vent.
 
I haven't completed calculations, but "Rejuvenated" was having intervals of about 30 minutes all day long.
 
i recorded 25 intervals for White Dome, varying from a minimum of 14 minutes to a maximum of 84 minutes.  The median was 25 minutes and the mean was 29 minutes.  The median is 5 minutes lower than the overall median from May 23 through June 20 and the mean is 7 minutes lower than the overall median from May 23 through June 20.  There were only two intervals exceeding 45 minutes, one of 74 minutes, and one of 84 minutes.  This was one of those days where there was a gap in the distribution of White Dome intervals, but I believe that is just a coincidence, given the relatively small sample size.
 
I now have another raven story to add to my repertoire.  Yesterday afternoon I left the lid for the canopy on the back of my pickup open to keep it cool in there.  A visitor driving past asked it that was my pickup.  When I replied yes, she pointed out that a raven had gotten into the back, opened up the tupperware container in which I keep my bread, taken the bread sack out onto the sidewalk area, pecked open the sack, and was carrying away chunks of bread.
 
Yesterday a female, probably in her 20's walked out past Pebble, across Crack, over the first dip in the sinter, out to the farthest sinter point so she could look into Cave.  My camera was in the pickup, so I didn't get a picture.  When I explained to her the danger of what she had done, she replied, "I don't need you to tell me what to do.  I make my own decisions."
 
Lynn Stephens
 
 		 	   		  
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