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

[lynn stephens]

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>The lower activity in May-June correlates with the spring runoff and high 
>water table.  The high 
>activity in September correlates to the end of the relatively dry summer 
>months.
>

Note that this phenomena of decreased eruptions in May, June, July, and August did not happen in the first half of the 1950s (per Marler's Table in The Inventory) before Giant went dormant.

Let's see if I can construct some speculative statements that will explain both Giant's pattern and Fan & Mortar's pattern  (which are different, see below).

High activity = April = river level is high from spring runoff causing slow down in Fan & Mortar.  But cold water hasn't had enough time to get to the critical point in Giant's system to cause decline in activity??
Low activity = May- = spring runoff and high water level in the river have impacted both Giant's and Fan & Mortar's plumbing systems.  

Mixed activity = June, July, and August
    Water level has gone down enough so Fan & Mortar are active again
    Cold water still impacting Giant's system so Giant isn't very active.

High activity = September = end of relatively dry summer months.  The water level in the river stays high enough in July and August from snow in higher elevations melting off to account for decreased activity in those months.  Moisture in September starts falling in the form of snow, water level in river starts increasing.  Fan & Mortar fell impact sooner than Giant and start slowing down a little bit.  It takes a few weeks for cold water to impact Giant's plumbing system so Giant stays at higher activity level.


>Fan and Mortar also do this.  They like summer but hate spring.


Fan & Mortar don't like April and May, as shown in this table analyzing F&M eruptions for 1997 through 2005.  (Note:  It is probable that I don't have all the eruptions for the shoulder seasons--March and April, November and early December, especially for 1997.)

	Fan & Mortar (1) 	Giant (2)
Month	# of
eruptions	
Percent	# of eruptions	Percent
				
Jan	35	10.1%	20	11.8%
Feb	42	12.2%	12	7.1%
Mar	25	7.2%	13	7.7%
April	19	5.5%	19	11.2%
May	15	4.3%	4	2.4%
June	27	7.8%	3	1.8%
July	37	10.7%	8	4.7%
Aug	38	11.0%	9	5.3%
Sept	29	8.4%	23	13.6%
Oct	32	9.3%	20	11.8%
Nov	16	4.6%	19	11.2%
Dec	30	8.7%	19	11.2%
Total	345		169	

As Jeff noted, Fan & Mortar like summer--July and August--but hate spring--April and May.  

The monthly patterns for Fan & Mortar and Giant are not synchronous.   Comparing the monthly percentages for F&M with those for Giant, Giant likes April but Fan & Mortar does not.  Fan & Mortar somewhat like June but Giant dislikes June.  Fan & Mortar like July and August but Giant does not.  Giant's "favorite" month is September, but Fan & Mortar's activity starts to decline in September.  I'll hold off on making comments about Fan & Mortar's November activity because I suspect some eruptions in 1997 and 2001 may not have been recorded in the OFVC logbooks.



>Aurum hates the dry months, but then again, it seems to need extra ground 
>water or it gets too hot to 
>erupt.

This is similar to what I observed at Mickey Hot Springs (Geyser).  Each time my father and/or I visted when ground water levels were high, the feature was a geyser.  Each time we visited when ground water levels were low, it was a perpetual spouter.


>There are at least two examples of rainstorms repeatedly affecting geysers at 
>Shoshone.

I think Dick Powell may have also documented this at Botroyidal.


>I've seen no papers on how cold groundwater affects hydrothermal systems.  Has 
>this been studied?

Thank you for providing the two references in your next post.

I haven't read the papers but I think the impact is going to vary from geyser to geyser--sometimes there is a positive relationship, sometimes a negative relationship, and no relationship.  And when there is a relationship, the extent of the relationship or timing of the impact is going to vary from one geyser to the next perhaps depending on the nature of the plumbing systems, connections with other thermal systems, etc.

Lynn Stephens


 
 
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