[Geysers] Geyser Report (10/6/05) Stephens

[Tara Cross]

>Could anyone fill us in with information about the last two or three 
>eruptions of Fan and Mortar this summer? Was there anything unusual about 
>them that might have given a hint that they would enter this dormancy?

This answer is based on the obvservations that I have made myself and 
collected from others since Fan & Mortar reactivated from their previous 
dormancy (May 1998-January 2000).  Also, this is off the top of my head--I 
don't have my logbooks with me at the moment.

While there were a few "weird" things that occurred in the two weeks before 
August 8, there was nothing that pointed towards a long-term dormancy in any 
concrete way.  The oddest thing that happened was the July 26 eruption that 
was not preceded by any events or Main Vent splashing.  The only other time 
I saw eruptions occur without events or Main Vent splashing was in the 
spring of 2002.

However, to say that this observation, or any other observations of "weird" 
behavior, would give a clue of impending dormancy would be a huge stretch.  
The usual sign of impending dormancy is lengthened intervals.  This did not 
occur, as Fan & Mortar chugged along at fairly regular 2-4 1/2 day intervals 
from June 22 through August 8.

On August 5, we observed a "fake lock" of High Vent, where High went into 
lock-like behavior by itself (not joined by Gold or Angle) and then stopped 
with no resulting eruption.  While this was only observed to happen once in 
2005, it was seen at least 3 times in 2004 and never in association with a 
distinct change in behavior.

Historically, the best sign of impending dormancy has always been the onset 
of the annual "spring slowdown" in April, May, and/or June.  Even in years 
when Fan & Mortar remain active, it will often lengthen its intervals for 
1-3 months in the spring.  So, this dormancy was unexpected even based on 
this very limited indicator.

--Tara Cross
fanandmortar at hotmail.com