[Geysers] Giant 11/1/07 details

[Tara Cross]

This report covers activity in the Grotto/Giant area leading up to the 11/1/07 Giant eruption. Some of this information will be repeated from previous reports for the sake of thoroughness. October 27 1131ie Grotto Fountain1141 Grotto, d~4m (weak start)1148 Giant HP, d=1m58s.  Feather, Feather Sat, and Rust only, Mastiff did not overflow, and Bijou did not come on afterwards.  I'm quite certain that this was the first since the previous night's eruption, a mere 12 hours later.~1330vr Grotto Fountain~1330vr Grotto - marathon, d~21h October 28 Grotto quit between 1000 and 1100.  I did not observe the recovery hot period. October 29 ~1000ie Grotto - marathon, duration unknown (still ie at 1645) October 30 Grotto was off when I arrived at 0850, and I estimated that it had shut off somewhere around 0500. 1259 Giant HP, d=8m31s.  Feather Sat started about 15s after Feather, Mastiff surged 4 feet, India 100% covered. After the recovery hot period, I escaped from the horrid weather (2 hours of pouring rain followed by 4 hours of huge snowflakes that blanketed the basin with 3 inches of heavy snow).  When it finally cleared up, I went back down to check on Giant. 1749 Giant HP, d=5m10s.  Feather Sat active, Mastiff boiled to 1 foot, India 60% covered.1825 Grotto Fountain, d=23m (no Grotto)1850ie Giant HP, d>2m.  Feather & SW Vents only. October 31 Based on the solo Grotto Fountain I had observed, I guessed that Grotto should have started around 2100 on the 30th.  Grotto was i.e. at 0827 on the 31st, but it was not the same eruption from the previous night because Variable Spring was down about an inch and there was still plenty of water in Bijou.  Based on how things looked at Giant, I conjectured that Grotto had started around 0600-0700. I watched a bathtub at 0900, and shortly thereafter gave up on seeing anything more.  Grotto remained in marathon until almost dark.  I was keeping an eye on it from Grand, and at around 1900 I noticed that the steam cloud got much larger.  I am guessing that Rocket had a major, but since I could not see any water I cannot confirm it.  Then the steam cloud got smaller again, and it appeared that Grotto had quit.  I biked down to double check (it was dark by that time) and Grotto had indeed shut off for an estimated duration of 13 hours. I felt that since the marathon was relatively short, it was unlikely that Giant would erupt on the marathon recovery hot period.  Due to cold, darkness, and the lack of other gazers for company, I decided to go in for the night and return in the morning. November 1 Based on a 13-hour duration of Grotto, I calculated that the first eruption following the marathon should start between 0700-0800, so I hurried down-basin as soon as there was enough light.  The first thing I saw upon arrival was Grotto Fountain at 0730ie.  Grotto followed at 0742 with a weak start, and I proceeded on to check on Giant. I found Bijou on, but pausing on occasion (I didn't time them, but I think it was about every 10 minutes--I was too busy trying to stay warm).  The platform had puddles on it, so hot periods had occurred overnight.  It was difficult to tell how long it had been since the last hot period, but I guessed it had been 40 minutes or more.  I walked over to watch Oblong at 0751ns, and then returned to Giant.  Bijou had a pause, then came back on. At about 0810, I noticed that Bijou was off and there was water rising in Mastiff.  Feather overflowed, and the SW Vents started erupting about 15 seconds before the hot period commenced at 0812.  Feather Satellite came on 38 seconds after Feather, and Mastiff began to have steady boiling to 1-3 feet.  There were times when it was too steamy to see what Mastiff was doing, but the boiling continued to be strong and steady, sometimes reaching at least 4 feet.  At the 4-minute mark, India was 90% covered.  Mastiff went flat for about 30 seconds but then came back, boiling to 4 feet again (and maybe more, but I couldn't see through the steam).  I kept looking for something from Cave, but every time the steam cleared, I saw only vigorous boiling to an inch or less.  Mastiff's runoff increased dramatically, and India was completely covered by the 7-minute mark. Shortly after that, Mastiff went flat.  Bijou came on, along with splashing from the B-C Vent, and seconds later Mastiff dropped out of sight, 7m35s into the hot period.  I saw Feather and Feather Satellite weaken, and expected them to shut off--but after about 10 seconds they started to get stronger again.  Steve Eide, who was skating down the jugwalk from Grand, said that over the radio my voice went up about half an octave at that point.  I immediately exited the cage (for fear of becoming an ice statue) and started watching for vertical surges as I fumbled with cold fingers to get my poncho on.  The surging started after about a minute and progressed slowly--but it got stronger and stronger, until several large surges reached the height of the cone.  There was a surge well over the height of the cone, but I wasn't certain that Giant had started until I saw the wave of water roll the signs, 12m15s after the start of Feather. GIANT, 0825!!!  It was partly cloudy, but there was enough sunlight coming over the hillisde for the column to be backlit as it rose up into the sky.  The water fell back down in sheets, landing well beyond the cage.  Steve said that from his angle he had a good view of the "Giant Geyser" sign being carried 30-40 feet down the runoff channel.  The steam cloud was huge, but the wind was blowing enough to make the column visible for most of the eruption.  When the steam drifted towards the GIP, I noticed that Turtle was erupting with bursts to 2-3 feet, but I don't know when it started.  It was cold and cloudy, and the only other person we saw over the entire 99-minute duration of Giant was the ranger biking down to Riverside.  Grotto was still i.e. when I left the geyser basin at 1745, so it was yet another marathon. Thank you Giant, for another wonderful year. --Tara Crossfanandmortar at hotmail.com
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