[Geysers] Why doesn't Giant like May and June? (Stephens)

[lynn stephens]

THIS ITEM IS FOR THE PERSONAL USE OF THE READERS OF THE LISTSERV AND IS NOT TO BE REPRODUCED FOR ANY OTHER PURPOSE.

Tom and Genean:  I’ll update this, add a graph, and do some other rewrites and send it in about May 16 for the June issue of The Sput.

What is there about the months of May through August that Giant doesn’t like, at least since 1959?  One of the reasons I went over for opening weekend was my distrust of Giant.  When I headed toward the Park on April 20, beginning with the August 6, 2005 eruption and continuing through the April 19, 2006 eruption there had been 21 eruptions reported, for an average interval of 12 days.  At the time I'm writing this, there have been 3 more eruptions (or maybe even 4 if it erupted in the last 24 hours) and it’s been less than 6 days since the last eruption of Giant was reported on the listserv.  But Giant most particularly doesn’t like to erupt during the months of May and June, as shown in the table below.  (July and August fare a little better, but if you really want to see Giant erupt, try to watch it September through April.)

When I expressed my concern to at least some of the gazers there opening weekend, the response was, “But when Giant stopped erupting in May in 2000 and 2002 it hadn’t been erupting for several months with intervals of less than 2 to 3 weeks, or intervals even more frequent than that.”  However, in 1997 Giant started erupting in January, showed declining intervals through mid-April, then decided to have only one eruption in each of the months of May and June.  In 1998 Giant had been erupting for seven months at 3 to 5 day intervals before it went to sleep for 5 ½ months following the April 30, 1998 eruption.  Let’s hope 2006 isn’t going to be a repeat of 1997, 1998, 2000, and 2002 when activity early in the year gave promises that many people would have at least one and possibly several opportunities to see Giant during their summer trips only to watch Giant become sluggish or even go to sleep in May and June.

Giant Eruptions by Month of Occurrence
		
Month	# of eruptions	Percent
		
Jan	20	11.8%
Feb	12	7.1%
Mar	13	7.7%
April	19	11.2%
May	4	2.4%
June	3	1.8%
July	8	4.7%
Aug	9	5.3%
Sept	23	13.6%
Oct	20	11.8%
Nov	19	11.2%
Dec	19	11.2%

Note:  The number of eruptions in the table is 169.  Although there are 170 in T. Scott Bryan’s list (as of the April 30, 2006 eruption), #118 is listed as “?”.  If there was at least one eruption between #117 and #119, the percentage for November would increase slightly and percentages for each of the other months would have to decrease very slightly. 

Lynn Stephens 
 
 
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