[Geysers] August 27 Giant details

[Tara Cross]

A message from Tara Cross <fanandmortar at hotmail.com>

My apologies for the delay in getting this sent out.

August 26

0534 Grotto, electronic time
0733ie Giant hot period, d>2m.
0900 Bathtub, or "double bathtub," because the water came up and dropped twice.
~1400 Grotto off; d~8h30m.
1816 Giant hot period, d=9m56s.  Feather Satellite started 40s into the hot period.    Mastiff's boiling started about 45s into the hot period and was up and down for almost the entire duration, between flat at 3 feet.  Some of the boiling was wide.  At around 6 minutes, there was a boil to 4 feet, but it quickly dropped back down.  Mastiff's runoff just barely covered India.  Cave bubbled to an inch or two.  80 seconds after Feather quit it had a restart that lasted 2 minutes.  While Feather was on fairly strong (and Satellite joined in for part of the restart), the water level in Giant was not very encouraging and the best it managed was a few drops to ¼ of the way up the cone.

All in all, it was a better hot period than I had expected, just 4 hours after the end of a mini-marathon (or whatever you prefer to call it).  I was actually quite encouraged that if the energy stayed on the South side of the platform and Grotto did not marathon again right away, that there could be an eruption in the next day or two.  However, since I did not expect a good hot period before dark and it was rather chilly, I didn’t go out to Giant for any subsequent hot periods on the 26th.  I also do not know when Grotto had its first eruption after the marathon.

August 27

I was the first gazer to check Giant in the morning.  It was only a few degrees above freezing when I headed out, and there was thick geyser fog over the entire geyser basin.  When I arrived at Grotto, I found it i.e. at 0700.  South Grotto Fountain was also i.e. and there was heavy steam coming from the pool around Grotto Fountain, so I surmised that Grotto had started 30-40 minutes earlier.

When I arrived at Giant Bijou was on strong with steam and Mastiff was depth charging.  It was doing this in spite of the lack of evidence of a strong period any time recently.  The edges of India were damp, but the majority of it was dry.  It was also dry in front of Feather and the Southwest Vents.  I surmised that it had been at least an hour since the last hot period, and that hot period couldn’t have been very strong.

Events then progressed as follows:

0700ie Grotto
0700ie South Grotto Fountain
0743 Grotto off, but South Grotto Fountain still erupting (S.G.F. off by 0755)
0804 Giant hot period (d=2m24s).  SW 24s before Feather; F, SW, Mastiff light overflow.
0907 Bathtub; Mastiff rose and dropped twice and Feather overflowed.
1002 Giant hot period (d=33s).  Just Feather and SW Vents (which started before Feather) and no Mastiff overflow.
1058 Grotto Fountain, d=15m
1102 Grotto
1107 Footbath, water barely visible when standing on the railing.

At this point I reasoned that the next hot period had potential.  When the energy is on the south side of Giant's platform, Grotto tends to have fewer marathons and Giant has frequent, weak hot periods in between strong hot periods that come every 6-8 hours (or more, if Giant is getting ready to erupt).  It’s also common to see Bijou on strong and depth charging from Mastiff in between the weak hot periods.

The next time Bijou paused, I saw water rising very quickly in Mastiff.  The Southwest Vents started right away, 27 seconds before Feather began at 1131.  Feather Satellite joined in rather quickly, just 25 seconds after Feather, along with Rust.  During the first 4 minutes of the hot period, Mastiff was up and down, but mostly flat.  Most boiling was 6 inches to 1 foot high, but there was one boil to about 2 feet.  Mastiff put out moderate overflow.

Then, around the 5-minute mark, Mastiff's boiling increased to 2-3 feet and got wider.  Cave began to bubble more vigorously, reaching about 3 inches high.  Mastiff's surging became essentially steady, reaching as much as 4 feet high, and as wide as it was tall.  By this time Cave was boiling to 6 inches.  I thought it might go into eruption, but it never did.  (Apparently, though I have absolutely no memory of it, there was a point in the hot period when I accidentally called Cave to 2-4 feet when I meant Mastiff, but folks said it got them moving quicker so it's all good in the end.)

Mastiff was up and down again, a few inches to 2-3 feet.  It was about 7 minutes into the hot period when the surging suddenly increased dramatically, first to 4-5 feet, then 6 feet, then a very wide surge to 7-8 feet.  My calls, which had admittedly been rather blasé up to that point, got a lot more urgent, and I even added "You'd better get down here!" for people who were still on their way.

The surging dropped down to 4-5 feet, then back down to 2-3 feet, but remained steady.  By this time I had decided it would be a good idea to dig my video camera out of my backpack.  Mastiff continued to boil from a few inches to 3 feet until about 8 ½ minutes into the hot period, when it abruptly went flat and then dropped.  Feather and Feather Satellite began to weaken for about 15 seconds, but then they kept on erupting.  Bijou came on right away, and soon Feather was back at full strength.

Our attention then turned to Giant, where there was very little water in the cone at first.  Then low vertical water could be seen, about 9 ½ minutes after the start of Feather.  The surges built from only a foot above the rim to a third of the way up the cone, then two thirds, then the top of the cone.  Then the surging dropped down again and built again, until there was a large surge over the top of the cone.  On the next surge, Giant burst to 30 feet.  (The entire progression took about 2 minutes.)

GIANT, 1143!!!!

The column lifted slowly, reaching up towards the late morning sun against a bright blue sky.  Then the water came crashing down, landing on and thoroughly soaking the right-hand side of the monkey cage (nearly everyone had fled to the main boardwalk, except for Julie, who was up against the railing).  Spikes of water poked out the top to an estimated height of 160 feet.  The eruption was very angled, aided by the wind which blew the steam towards Round Spring.  The column was beautifully backlit for most of the eruption.

Since Grand was in its window, many visitors were able to see Giant, as well as a fine crowd of gazers, some of whom were seeing their first Giant start (congratulations to all).  Most people headed back up to Grand after the eruption began to wane but I waited to the end of the water, which was at 100 minutes exactly.  The interval was 8d10h22m.

(Had the interval been 8d10h23m, I would have officially entered the Twilight Zone.  On August 27, 2001, I saw Beehive at 1107.  Afterwards I decided to head to the Lower Basin to try to catch Fountain.  I was pulling into the Fountain Paint Pot Parking lot as Fountain was called.  The time was 1143.  I did not find out until later that Giant had started at 1144.  I'll just say that this eruption felt a little bit like payback.)

--Tara Cross
fanandmortar at hotmail.com
_________________________________________________________________
Use Messenger to talk to your IM friends, even those on Yahoo!
http://ideas.live.com/programpage.aspx?versionId=7adb59de-a857-45ba-81cc-685ee3e858fe