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Observations for 2021 September 13


With no reports on Grand and it being at almost eight hours, made a quick trip out to check on it. Was one of the foggier days for this trip, and I could tell Sawmill was erupting from the runoff, but I couldn't see it. Wasn't until I got to Rift that I found a quiet, empty crater at Grand. So probably erupted as much as two hours earlier.

Was coming out for the next Grand eruption, but first I got to see a less than four minute long Castle minor eruption. No Turban Delay, but did have to wait through several Turban eruption intervals before Grand started. The first burst lasted almost nine minutes, and the pause between the bursts was short. Unlike a number of the recent two burst eruptions, the behavior in Grand's pool was leaving no doubt of a second.

Did a check on East Sentinel, which is unchanged. Still having 19 minute cycles, although the first heavy overflow I saw was not followed by any activity from the South Rim. From there, spent about 45 minutes at Fan & Mortar, and decided that it was in garbage mode and since it was so soon after the previous eruption, I was wasting my time there.

Found that I can get from the cabin to Fan & Mortar in about seven minutes. Only came close to hitting one person who "had their head up their app". (Old Faithful was in eruption. A whole line of people lined up along the fence along the Inn, except one geezer who had to stand in the middle of the trail to get his selfie, and immediately look at himself in the little screen.) Got there with little time to spare. Didn't drop my pack or get out the raincoat, as by this time Upper Mortar was already having large minor eruptions about a minute apart. After the second minor that I saw, Angle vent looked strange, as if it was in a steamphase, while there was no activity from Gold and only moderate from High. After the third huge minor, when all of Mortar was quiet, suddenly Fan's East Vent kicked in, and then all the vents joined in.

This was the third Fan & Mortar eruption in a row that seemed to come with little warning. The prior activity of Fan did not have the intensity of the previous eruptions, since this time Mortar was dominating. But in each case, there was something about the activity that said that this was not a normal event cycle, and that people needed to be informed.

Following that excitement, went out for a sunset Grand eruption. In the Sawmill Group, the water levels were high enough that Slurp was quiet. Belgian and Crystal were way down, about 6cm.

I believe I saw the Delay eruption when I arrived, as it was a long eruption, and the next Turban interval matched the usual behavior -- no overflow. Also, Turban initiated the eruption, which seems to mostly happen only after a Turban Eruption Delay.

That One Burst Grand eruption was also right at sunset, so the water column of Grand was nicely tinted (and not from smoke) as the sun shone through a gap in the clouds. During the wait, West Triplet also had a short, less than seven minute long eruption, which shut down the other sputs for a bit, but they were back to erupting after the Grand eruption.