Last Known Eruption
13d 14h 0m ago

Interval Statistics

Interval Count30
Min33m
Max15y 2d 15h 24m
Mean1y 182d 12h 53m
Median68d 5h 39m

Latest Notes

Note IDStart Time (US/Mountain)End Time (US/Mountain)EntrantNote
19640 18 Sep 2021 @ 0738 --- Graham Still right side boils.
19630 17 Sep 2021 @ 0657 --- Graham Still right side boils.
19627 16 Sep 2021 @ 2014 --- Tara Brief look, right side boiling
19596 16 Sep 2021 @ 0649 --- Graham Still right side boils.
19591 15 Sep 2021 @ 1800 --- Dan A Right side boiling continues
19588 15 Sep 2021 @ 1335 --- Dan A Still right side boiling with cycles every 20 minutes or so
19573 15 Sep 2021 @ 0655 --- Graham Still right side boils..
19572 15 Sep 2021 @ 0030 --- William right side boiling only.
19569 14 Sep 2021 @ 1745 --- CrisG right sided boiling still
19565 14 Sep 2021 @ 1430 --- Dan A North side boiling continues
19554 14 Sep 2021 @ 0725 --- CrisG Right side boilfest continues
19531 13 Sep 2021 @ 1542 --- Suzanne Still boiling on the north side and cycling about every 19 minutes
19523 13 Sep 2021 @ 0909 --- Brian Still in north/right side boil mode
19518 12 Sep 2021 @ 1715 --- Ben VL N. Side boiling, did not stay for an entire cycle.
19511 12 Sep 2021 @ 1447 --- Brian Right side boil-fest continues…
19507 12 Sep 2021 @ 0905 --- William Right side boiling only
19502 12 Sep 2021 @ 0653 --- Graham Still right vent boils.
19492 11 Sep 2021 @ 1950 --- Graham Still right side boil cycles.
19496 11 Sep 2021 @ 1250 --- MarioD Observed from 12:50 to 13:15; several cycles of right side boils noted, some high enough to splash water onto the platform above
19473 11 Sep 2021 @ 0749 --- Graham Still right vent boils.
19451 10 Sep 2021 @ 1840 --- Graham Right vent boils, cycles 17 to 20m reported all day.
19414 10 Sep 2021 @ 0648 --- Graham Still right vent boils.
19395 09 Sep 2021 @ 1745 --- Suzanne Splashing continues from the North vent, cycling every 19 to 20 minutes.
19384 09 Sep 2021 @ 0633 --- Graham Still doing right side boils.
19378 08 Sep 2021 @ 1945 08 Sep 2021 @ 1950 Tara Very brief check, boiling on north/river side, ordinary cycle
19376 08 Sep 2021 @ 1740 --- Dave W All activity still on north side.
19366 08 Sep 2021 @ 0645 --- Graham ES right vent still active. No transition to left yet
19361 07 Sep 2021 @ 1200 07 Sep 2021 @ 1728 geysergaze No change in activity since this morning. 18-21 minutes cycles. All activity on the right / north -west side. Left side not doing much.
19345 07 Sep 2021 @ 0633 --- Graham Right North vent still the active one. Peak 0641, gap, 0801, gap, 0859, gap, 0956, gap, 1152, 1211, 1230,
19337 06 Sep 2021 @ 1800 --- Graham All today's reports have been of N vent cycles 19 or 20m long.
19326 06 Sep 2021 @ 0752 --- Suzanne Boiling from the north side and cycling every 20 minutes. At the peak height water flows into the far left (south) runoff channel and the alcove vent on the north side splashes a few inches above the rim, enough to form puddles on the north side of the crater. The previous peak was at 0751.
19321 05 Sep 2021 @ 1825 --- Graham Observed 3 cycles of 20min with North vent boils. Similar reports all day from other observers.
19317 05 Sep 2021 @ 1515 05 Sep 2021 @ 1635 Tara cycling about every 20 minutes with boiling on north (river) side
19307 04 Sep 2021 @ 2039 --- Graham After normal splashy cycle, pool dropped and went calm. Side vents were steamy and noisy for 7m. Pool stayed calm and did not rise for 10m. 2049 water rose with strong North River side boil this time and then dropped. Side vents steamy and noisy 2056. 2059 water rising. Right side boil, then left joined in and it erupted!
19319 02 Sep 2021 @ 1600 --- Graham 20min cycles of boiling from right North vent, similar to yesterday.
19237 01 Sep 2021 @ 1405 01 Sep 2021 @ 1720 Graham 20min cycles from below overflow to peak water. Vent on River side active, holding thick boil at rim height at peak and splashes 1 foot over rim. Cycles very regular in fill rate and boiling. Similar to what Micah reported on 5 Aug.
19169 30 Aug 2021 @ 2000 --- Dan A 1955 big surging on south side of pool that built into bursting from the center pool around 8’. Water was also bursting from one of the holes
19163 30 Aug 2021 @ 1202 30 Aug 2021 @ 1445 Tara I suspect a major eruption has occurred recently, grass is matted on the SSE side, water is slightly murky. Minor activity has changed drastically from 1 week ago, when I saw only moderate overflow and weak 6-18" cyclical boiling on the north (river) side. Today I arrived to find heavy overflow and boiling to 1-3' on the south (bank) side. At 1204 his built to surging to 3-5', followed by churning bursts from the center of the pool reaching 4-8' for about a minute, with overflow spilling over all sides. At 1206 the water level began to drop and the surging subsided. As the water fell to its lowest point 1.5' below the bathtub mark, the side vent to the south began to gurgle and then splash weakly to 1-3' for about a minute. Boiling and bursting continued on the south side from a low water level reaching 1-3' but becoming weaker as the water level rose. 1217 the pool reached overflow again. 1218 variable boiling resumed on south side, highest water level 2" below bathtub mark, 1220 water level drop to 6-8" below mark. 1227 water had risen to 2-3" below mark, pool mostly calm with some light boiling, still holding at 1235. 1240 water level 2" below mark, increasing boiling on south side. 1252 water level rose to bathtub mark, heavier overflow, boiling 1-3' on south side. 1254 boiling extending into center of pool. 1255 water level dropped slightly and bursting began that built to churning at 1256. Action similar to previous minor but weaker, max height 4-5' and d~1m. Side vent gurgling after but only a few.drops of water seen. 1257 water level drop to about 1' below mark. 1306 water level back up to mark, boiling extending frol south side into center of pool. Side vent stopped gurgling at this time. 1307 bursting and churning d~1m h~4-6', 1309 water level drop & side vent gurgling with spits 1-3', more bursting briefly at 1310. 1315 water level holding 8" below mark, side vent continues to gurgle. Cycles continued to stabilize at about 20 minutes, with peak boiling reaching ~4' occurring as the pool dropped.
19136 28 Aug 2021 @ 1918 --- User34 Overflowing and boiling vigorously from the righthand side
18842 05 Aug 2021 @ 1407 05 Aug 2021 @ 1503 Micah Kipple East Sentinel is cycling it's water level up and down approximately every 20 minutes (first ovf to first ovf). Upon reaching overflow, superheated boiling 3-12" high commences on the North (River side) of the crater. This waxes and wanes until about 10 minutes after first overflow, when the entire pool suddenly lifts ~3" and the superheated boiling surges to 2', sending runoff trickling down the backside into the river. When the pool drops about 15 minutes after first overflow, there is some small lazy bursting from a single vent on the south (Bank) side of the pool to about 12". Then the water starts coming up and the cycle repeats.
18803 02 Aug 2021 @ 0945 --- hkoenig Appears to have had major eruption in last couple of days. Some catch basins full. Dead grasses pointing upriver and dead plants as much as 10m from the vent in southern alcove. Flow marks still visible at spots. 25cm high boiling along downstream rim. Based on Tara Cross' comment, added an eruption entry for ~2021 Aug 01 01:00
12400 07 Jul 2019 @ 1152 --- User34 Flat, river flowing well through near channel.
9929 29 Aug 2018 @ 1720 --- Micah Kipple Still flat and being drowned by the river.
9204 15 Jul 2018 @ 1850 --- Micah Kipple Pool surface quiet but steadily overflowing and almost imperceptibly rising and falling. Side vent is completely inundated by the side channel of the Firehole.
5217 22 Aug 2017 @ 1041 --- CrisG pool full and quiet. no bubbling or splashing.
4075 09 May 2017 @ 1115 --- mhreed Placidly overflowing.
3519 21 Aug 2016 @ 1030 21 Aug 2016 @ 1055 mhreed Energetic boiling/splashing from left two vents. Splashing on push reached 3 ft. with highest droplets to 5 ft. and agitated the entire pool.
3197 03 Jul 2016 @ 1332 03 Jul 2016 @ 1530 JSJ East Sentinel Geyser was in minor eruption from 1332 to 1530 from the side vent. Activity ranged from moderately weak to moderately vigorous splashing. Pool water level varied, with episodes of good overflow to intermittent overflow to no overflow. Brief pauses in eruptive activity at 1401 and 1455 and 1514. Moderately vigorous splashing at 1437 to 1438 wet part of the cone. No major eruptions observed, angled or vertical.
3023 09 Jun 2016 @ 1200 09 Jun 2016 @ 1320 CrisG Pool full and quiet. No spashing or bubbling noted.
2766 20 Apr 2016 @ 1430 --- User34 Boiling has switched to the right side, area looks washed, and hillside damp, may have been a major that was seen on the webcam last night
2729 15 Apr 2016 @ 2000 --- WillBoekel grass mowed over above feature. has erupted recently.
1974 24 Jul 2015 @ 1500 24 Jul 2015 @ 1645 Micah Kipple East sentinel and it's side vents are going through cyclic activity. Every 20-25min East sentinel will have a surging minor eruption from 4-8 feet from the north vents. Simultaneously the side vents on the platform will erupt to 3 feet. The minor dies down into strong boiling which continues through the extra overflow and drop just before the minor. There is no more evidence for major eruptions in the past week.
1113 22 Jul 2014 @ 1228 --- WillBoekel Having 1-2inch simmering on river side of the crater at 1228
1080 13 Jun 2014 @ 0000 13 Jun 2014 @ 2359 Micah Kipple Sitting at overflow completely quiet, no evidence of activity of any kind. The river channel adjacent to it is completely full, the side vent located in the channel is completely drowned.
No attachments for this geyser.
Baseline does not exist.