[Geysers] Fan & Mortar 9/21/2010 @ 1335 Report

[Jacob Young]

I was fortunate enough to be sitting at Fan & Mortar for one of the shorter intervals of 2010.  This was the first event cycle I saw during the interval and I started watching it at the 3d08h mark @ 0830 on 9/21.  I was also at the previous event cycle that led to the eruption on 9/18 @ 0211.  The two event cycles were very similar in that they featured lots of Bottom Vent action except that the 9/18 cycle had Bottom Vent durations of ~10 minutes and seemed more organized with energy swinging nicely between Main Vent and Bottom Vent and Main Vent and River.  In the 9/21 cycle, Bottom Vent was intermittent, erupting often but unsustained for more than 30 seconds at a time before disappearing completely for a few seconds.  River also seemed to have a hard time coming on.  Also, before the River pause, Main Vent starting continuously splashing with a couple of 'white stuff' bursts.  Based on other non-erupting cycles I've seen, I didn't take it as a good
 sign, but I was happy with the results.  Here are my notes from the cycle:

1230 Main Vent splash
1230 Bottom Vent intermittent
1234 Main Vent splash
1236 Bottom Vent quit
1238 Main Vent splash
1240 Main Vent splash
1240 Lower Mortar w/ water
1244 Energy swinging from Main Vent to Bottom Vent/Lower Mortar several times
[swirling winds made it difficult for me to see what River Vent was doing until Barbara showed up to help with viewing from the bridge]
1246 River on (weak?)
1248 Bottom Vent on
1251 River pause(?)
1252 River on (strong)
1258 River pause
1301 Bottom Vent eruption (short ~20sec)
1305 Bottom Vent splashing/Lower Mortar splashing/Main Vent splash
1308 River on / Bottom Vent short eruption
1309 Main Vent splash / Bottom Vent short eruption
1317 Gold spraying mist
1319 Gold on followed immediately by Angle on
1326 Water levels good, Gold erupting to 3-4ft in 'pulses'
1328 Gold and High lose water to the point of barely erupting for a disappointment-inducing 1+ minute, Angle splashing increases
1328 Barbara thinks about getting on her bike to leave
1330 Gold and High back to erupting strongly and climbing...
1332 Lock (may have happened at 1330 but I was too incredulous to call it)
1335 Eruption started by East Vent

Viewing conditions were sunny skies with some swirling wind and lots of lucky tourists.  Overall, I think the eruption and after-bursts were less powerful than that of 9/18, but the 1st burst was still 18 minutes long and it was all amazing!

Jake Young