Geyser Notes

Got out to Bijou Cage about 3h45m after the midnight hot period. Turned the corner and noted that Riverside was in eruption, which I hadn't noticed while tying the bike at Grotto. Dropped the pack and was fishing for my notebook when I realized that the noise on the platform didn't seem right, too noisy, and one of them sounded like Feather. Got the spotlight out of the pack to discover that Feather was not only in eruption, but Giant was surging. It was a restart. But after a couple of strong Giant surges, things died down.

Just as the alarm went off, Mike Keller started to announce a fill in Mastiff. This turned out to be a strong bathtub with Southwest Vents, but it was still just 2-1/2 hours since the last activity. This gave us the chance to take some time in getting ready to head out.

Arrived at the Cage just before 07:00. Grotto was active, but nothing much else was going on. Rocket finally erupted about an hour and a quarter later. There was a series of pauses lasting from 45s to 1m20s until we finally got a long, 3 min. pause at 10:30. I used that as the opportunity to make a quick run to the cabin to remove some clothing layers and get ready for a longer wait. As I arrived at the cabin, I heard that Grotto had started another eruption.

That eruption of Grotto was short, with Rocket just 26 minutes later. The series of Bijou pauses continued for several hours more, with another Grotto eruption with an interval of about 3-3/4 hours, one that had no Rocket eruption at the end.

Finally, 13-1/2 hours after the previous hot period, we finally got a long pause and Feather. The water rising in Mastiff took its time, about three minutes, to make itself visible. It was another two minutes before Feather started. Then things started happening. Mastiff overflow was strong, and kept getting stronger. The surging was as high as any of the good hot periods. After about 5 minutes, the surging turned into an actual Mastiff eruption.

Over the next couple of minutes Mastiff kept getting higher, with some bursts at least three times the height of Giant's 10 foot high cone. At that point, Giant, whose water level had been high for quite a while, joined in and within two minutes we had the first Mastiff function eruption since late April.

At the platform, I had set up a camera on a tripod to record the hot period, while near the end I started recording the hot period with my phone. As the eruption started, the water was thrown our way, soaking the north end of the cage where I was. The water was still warm, and I quickly shoved both cameras into pockets to protect them. (Videos will be posted when I get back home).

Then I rushed, as much as I could, to get to the 60 meter baseline marker. The boardwalks were crowded with people, but I was there within the first few minutes of the eruption. The best height measurement I got was 74% of 60 meters, which works out to about 150 feet.

The eruption didn't look that short, it looked huge. But I also know that the angle to the top of the spikes was less that 45°. I reviewed my procedures, and confirmed that the baseline I was using appeared to be the 60 meter one (unless the baseline got moved by a repair). The only thing I can conclude is that Giant must've put up some massive spikes at the beginning, but quickly settles down to something not as high. (Much like what Grand does.) Or all those heights of 200+ feet were not based on measurements, but were optimistic estimates.

I do know that years ago I measured a height, well into an eruption, at 72 meters from that point. That eruption was definitely more than 45°. Not sure to make of all this.

The weather conditions were almost perfect. There was a bit of wind, but after the intial surge, the cage didn't get wet again, and the wind pushed the steam away to the north. It was late afternoon, so there was a full double rainbow seen from my vantage point in the cage.

Two signs, the Giant sign and the "Danger" sign rolled from their locations down in front of the cage platform.