[Geysers] Geyser Report Tuesday, September 25, 2012 -- Old Faithful

[Lynn Stephens]

THIS POST IS FOR THE PERSONAL USE OF THE READERS OF THIS LISTSERV AND MAY NOT BE REPRODUCED FOR ANY OTHER PURPOSE, INCLUDING PUBLICATION IN THE TRANSACTIONS OR THE SPUT (other than Tara's use in the Current Geyser Activity column). Barbara wrote:

> The "Current Geyser Activity" report updated 9-1-12 shows Old Faithful
> being predicted at 88 or 62 minutes --plus or minus 10.
> The last Giantess eruption was 9-13-11, the last Giant 1-22-10E, last
> Steamboat 5-23-05, last known Echinus 6-18-12 (and the one before that
> was 12-7-09).  All this just in case you've lost track of how long
> it's been......
I just finished transcribing the OFVEC logbook pages for 2011, (the updated log has been posted on the GOSA website).  Thanks to MaryBeth Schwarz for copying the pages (3/15/11 through 3/15/2012) for me this summer. I thought I was seeing more Old Faithful intervals in the 80 minute range during the later months of 2011.  (I set the spreadsheet to calculate intervals from the start time rather than transcribing the intervals recorded in the logbook because many of those intervals have been miscalculated.)  An analysis of the intervals indicated a shift in the distribution toward shorter intervals occurred in late October, 2011.  Although the entire distribution shifted toward shorter intervals, the largest change involved a shift from 90-99 minute intervals toward 80-89 minute intervals.  The percent of intervals in the 90 - 99 minute category declined from 52.8% to 31.9%, a decrease of 20.9%.  The percent of intervals in the 80-89 minute category correspondingly increased from 26.1% to 50.0%, an increase of 23.9%.  My impression from eyeballing the 2012 logbook pages and data on geysertimes.org since March 15 is that the distribution has not shifted back.                8/1 to 10/28         10/29 - 12/31                      %                        %<60              .9                           .760-64          2.2                         3.365-69          1.3                         3.370-74          1.0                         2.0 75-79          1.3                         2.680-84          7.1                       20.885-89        19.1                       29.290-94        30.4                       17.695-99        22.4                       14.3100-104      8.6                         6.5>=105        5.7                         1.3 count           687                       154min               41 min                   55 minmax             116 min                 116 minmean             91 min                   87 min median           92 min                  88 min  Lynn Stephens 		 	   		  
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