[Geysers] West Thumb

[carolyn loren]

Here's a short  report from Peter Hamel, the interpreter at Grant/West Thumb:
 
We (Chris Brown, Becca Alfafara, and I) have noticed and documented some changes in West Thumb. Most notably, Twin Geyser in late July (perhaps around July 20th a Sunday) heated up and began overflowing forming a new microbial mat. Previous to a small swarm of quakes in West Thumb, Twin Geyser had been about 158 to 160 F. Following the quakes, Twin heated up to 199 - 202F and overflowing. This activity has now subsided a bit. Twin's vigorous roil declined somewhat by Dec 28th and is now completely gone. There are only sporadic bubbles rising in the basin now. The water level has dropped some 6 to 8 inches and the water temperature on 1/2/09 had dropped to 176F. I plan to get down and try and get another temperature Friday/Saturday this week. In addition, Black Pool has cooled considerably. Throughout the summer, Black Pool had been a steady 178F to 180F and on 1/2/09 the temperature had fallen off to 156F. Abyss Pool has dropped from the mid 150s (156F mostly) down to the low 140s/upper 130s (138 to 141F). I am not sure if this temperature decline is earthquake related or simply a function of winter cold temperatures. We will continue to monitor these features over the coming weeks to see what the temperatures do. Water levels in both pools continues to run off at rates the same or very similar to summer levels. Water continues to support microbial mats from both pools as it has since April. There may be a slight shift in run-off location from Black Pool as it appears that one mat is "drying" without as much water over it, but I have seen this occur throughout the summer. Via Carolyn Loren
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