[Geysers] Data on Grand Geyser

[jimscheir at aol.com]

I decided to put the data I gathered this season on Grand geyser into a spreadsheet to analyze the results. I was in Yellowstone from May 11, 2011 until October 3, 2011. I acquired data beyond just times (code such as T2C) on 164 eruptions. I was an observer on about 95% of them and received the information on the rest directly from gazers. While there were 12 days on which I have no data (2 days not in the park, several days monitoring Fan and Mortar instead, etc.), there are 29 days on which I have data on 2 eruptions. Here is a summary of the results.
 
1. Turban and Vent continued (C) when Grand stopped on 66 eruptions and quit (Q) on 98 before restarting.
 
2. Grand (G) started first 25 times, Turban (T) started first 129 times and 10 were unknown (Grand knew I was coming and decided to start before I was close enough to see which was first). Grand starts were somewhat clustered as there were several periods of 2 weeks or more when no Grand starts were recorded.
 
3. The burst average recorded was 1.555 with N = 164. This included the 6-burst eruption in May and eleven 3-burst eruptions. The 6-burst eruption was a Grand start but only one 3-burst eruption was a Grand start.
 
4. There were 10 eruptions coded as 2* (meaning an unusually long second burst) with 5 Turban starts, 4 Grand starts and 1 unknown. There were 2 coded as 3# (meaning an unusually long third burst) and both were Turban starts.
 
5. Monthly burst averages varied during the season as illustrated in the table below.
 
Month      # observations     Burst average
May-------------24----------------------1.792
Jun--------------36----------------------1.556
Jul---------------40----------------------1.450
Aug-------------31----------------------1.613
S-O-------------33----------------------1.455
 
Total            164                    1.555       

In drawing any conclusions it must be remembered that these are only about 40% of the eruptions of Grand during the time period described.
 
If anyone would like a copy of the data please contact me at jimscheir at aol.com. It is in Excel 2007. 


Jim Scheirer

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