[Geysers] Characteristics of Grand's Eruptions

[Lynn Stephens]

Karen Webb was right--the proportion of Grand versus Turban starts has changed since the switch to shorter intervals.  The trend toward a larger proportion of Grand starts began increasing even before the switch to the streak of sub-6 hour intervals. Using data from geysertimes.org, I looked at Grand versus Turban starts since Grand started having intervals between 5 and 6 hours (using the 0846 8/30 eruption as the starting point through the 1803 9/14 eruption).  There were 42 eruptions during this time frame for which the start was listed:  25 (60%) Grand starts.  Looking backward from the 0846 8/30 eruption for the prior 42 eruptions for which the starting geyser was listed 31% were Grand starts.   Proportion of Grand Starts   Switch to current streak        60%   2012 prior to switch             31%   2011                                                               16%        Looking at burst data, the average may have decreased very slightly.  For the same time period (0846 8/30 through 18:03 9/14) burst data was shown for 45 eruptions:     1B = 31    68.9%    2B = 12    26.7%    3B =   2     4.4%   Mean = 1.36 The prior 45 eruptions for which the number of bursts was shown:     1B = 27   60.0%        2B = 17   37.8%    3B =   1    2.2%   Mean = 1.42 There is limited evidence showing the downward trend in the average (mean) number of bursts is continuing. (For comparison purposes, the average number of bursts in 1975 was 2.87.) Limitation:  Inclusion of information about starting geyser and burst data reported in the OFVEC logbook but not reported on geysertimes may yield slightly different results. Lynn Stephens       		 	   		  
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