Observations for 2026 August 25


It was dawn and I was walking down from Crested Pool when I saw what appeared to be an eagle flying low upstream along the Firehole River. When I got to the bridge, that's when Grand began to erupt.

Took a little longer to get over there, because the boardwalk between Sawmill and Belgian is in the hands of the trail crew. But arrived in plenty of time to catch the end of the first burst, which lasted just under nine minutes. After a fairly normal pause, I got well over two more minutes of activity.

2026-Aug-25 : 06:27:44 2*Q

 06:27:44	B1	--- d=08m50s
 06:36:34	P1	8m50s d=42s
 06:37:16	B2	9m32s d=02m21s
 06:39:37	P2	11m53s
 06:40:17	V&T Quit	12m33s

				     ΣB=11m11s	ΣD=11m53s

Since I was already up and around and prepared to be out for a while, there was no reason to head back in. Instead I went down to the Bijou Cage. The Giant platform looked like nothing much had happened recently. The area around the Southwest Vents was dry, and the small puddles in front of Giant looked like they came from its activity. There was a bit of water in the far runoff coming from Mastiff, but it was a cool, damp night.

Was there for nearly two hours, and saw a few small Mastiff surges, but the last one was almost an hour before I left. At that point, I went in for breakfast, and returned to the cage about an hour later.

This time I had barely settled in when Mastiff had a huge surge to at least two meters that lasted 45 seconds. Sometimes Bijou pauses after these surges, so I kept watching, and while Bijou did not stop, water became visible in Mastiff.

Water was not high, maybe down 30cm, and was only visible for less than 1-1/2 minutes. I saw one spit from the Southwest Vents. By the end, Bijou, which had never stopped, was erupting even stronger. It then began roaring with Catfish active.

Left the cage and the basin for a while, and about 1/2 hour later, Oblong erupted for the first time in several months. Returned to the cage briefly, just to confirm that nothing major had happened at Giant during Oblong's eruption.

Then headed over to Grand just in time for the Turban Delay Interval eruption. Was pleasantly surprised that we only had to wait four Turban eruption intervals before the One Burst Grand. The eruption started in shadow, but the cloud moved away by the start of Vent. Shortly after that, West Triplet also erupted.

2026-Aug-25 : 14:20:24 D4/G1Q

 14:20:16	Vent Ovfl	-0m08s
 14:20:21	Boop	-0m03s
 14:20:24	B1	--- d=10m12s
 14:20:27	Turban	0m03s
 14:23:28	Vent	3m04s
 14:30:36	P1	10m12s
 14:32:43	V&T Quit	12m19s

				     	ΣD=10m12s
	* * * * *
 13:02:49			d=04m38s D0	
 13:19:38	Int: 16m49s	d=04m15s D1	
 13:39:07	Int: 19m29s	d=03m54s D2	
 13:59:00	Int: 19m53s	d=03m50s D3	
 14:25:56	West Triplet
		      Grand: 21m24s

As we left Grand, we got to see the second Oblong eruption of the day. Thanks to the trail construction, we didn't try to backtrack to see it from the Grand benches.

From there, it was back to the Bijou Cage again. A half hour after my arrival, I got another large Mastiff surge (ten minutes after the previous, smaller surge). Two minutes later Bijou was off. Water never rose very high in Mastiff, and again there was only a splash or two from the Southwest Vents. The pause lasted 3-1/2 minutes, and once again, when Bijou started, it began to roar. Catfish and the C-B Vent also showed some activity at that time.

Went back out again in the late evening, after getting some overhead done back in the cabin and after waiting for a shower to pass. Waited almost an hour before finally got a large Mastiff surge that led to a Bijou pause. It was similar to all the previous pauses, with Mastiff showing visible water and a couple of Southwest Vent splashes. The pause lasted almost four minutes, and then began roaring after the restart. Grotto was erupting as I left, but I didn't notice the start.

West Triplet was in eruption as we arrived for the evening moonlight Grand eruption. Shortly after West Triplet ended Percolator also paused for about 1-1/2 minutes. It was disconcerting for there to be silence out there.

There was little runoff prior to the Grand eruption start. The start itself was sudden and explosive. By a nearly full moon, the second burst seemed to be tall and thin.

2026-Aug-25 : 22:03:54 D0/G2Q

 22:03:54	B1	--- d=09m14s
 22:13:08	P1	9m14s d=23s
 22:13:31	B2	9m37s d=40s
 22:14:11	P2	10m17s
 22:15:01	V&T Quit	11m07s

				     ΣB=09m54s	ΣD=10m17s
	* * * * *
 20:56:31ie	West Triplet
 20:57:49			d=03m39s	
 21:17:56	Int: 20m07s	d=03m39s	
 21:37:29	Int: 19m33s	d=04m02s	
		      Grand: 26m25s

And this evening I learned that Ernesto has left the basin.