[Geysers] Geyser Report--Grand (Stephens)

[lynn stephens]

This morning while Butch Bach and I were watching what turned out to be a 2-burst Grand, he asked if I knew what the average number of bursts had been lately.  I replied that I hadn't run statistics since sometime last summer, but thought it had been about 1 3/4 at that time.

This afternoon after the 4-burst Grand, I decided to analyze data from July 2005.  (I haven't xeroxed the August logbook yet)  During July 2005, there were 51 eruptions for which the burst count was reported in the OFVC logbook.  

                      Count   Percent of   Percent When 
                              Total        Initiator known
Grand initiated        13        25%              27%
Turban initiated       35        69%              73%
Unknown                 3         6% 

The eruptions were almost evenly split on whether Vent & Turban quit immediately after Grand (and then restarted several minutes later) or whether Vent & Turban continued after Grand stopped--Vent & Turban continued after 26 eruptions and quit after 25 eruptions.

Burst Count:                      Count      Percent
     1 burst eruptions             31          61%  
     2 burst eruptions             18          35%
     3 burst eruptions              2           4%

Average burst count for the 51 eruptions for which the burst count was reported in July -- 1.43.

There were no 4 burst eruptions during July.  There was one on June 21 at 22:57.  There was a note in the logbook that that 4 burst eruption may have been the first one reported since October 2003.

Today's eruption started at 14:26 with blue sky and sun on the eruption.  The June 21 eruption was Turban initiated; today's eruption was Grand initiated.  Grand erupted on the first Turban cycle after Rift had started, which also happened to be the first Turban cycle after the prediction window opened, so there weren't many visitors there and I think I was the only gazer at Grand for the eruption, although some of the gazers waiting for a Giant hot period also had various views of the eruption.  (MaryBeth is in Seattle this week, so I'm doing some of the Grand eruptions.)  

The first burst lasted 6m54seconds.  The visitors around me were disappointed when it stopped and couldn't understand why I was excited until I reassured them that the pool still had water and Grand would erupt again.  The second burst ended at 8m20seconds and the pool had plenty of water, so I was telling people to stick around.  The third burst ended at 10m47seconds and the pool still had some water.  After a pause of 56 seconds, which seemed to take forever, the fourth burst wowed the entire audience.  Total duration of the eruption was 12m16seconds.  Vent had turned to steam before Grand quit and Vent and Turban quit immediately at the end of Grand's eruption.  It took 21 minutes from the time Grand ended and V&T quit until V&T restarted.  I didn't stick around to see when Rift ended.

Lynn Stephens

 
 
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