Last Known Eruption
17h 49m ago

Latest Eruptions

Eruption DurationInterval
25 Oct 2021 @ 0809 ie20h 43m
24 Oct 2021 @ 1126 ie wc1d 4h 19m
23 Oct 2021 @ 0707 ie wc20h 45m
22 Oct 2021 @ 1022 ie21h 4m
21 Oct 2021 @ 1318 ns21h 13m
20 Oct 2021 @ 1605 ie2d 8h 14m
18 Oct 2021 @ 0751 ie wc17h 37m
17 Oct 2021 @ 1414 ns4h 59m
17 Oct 2021 @ 0915 ie23h 50m
16 Oct 2021 @ 09251h 18m
16 Oct 2021 @ 0807 ie wc16h 23m
15 Oct 2021 @ 1544 ns5h 58m
15 Oct 2021 @ 0946 ie wc3d 12m
12 Oct 2021 @ 0934 ie1d 2h 12m
11 Oct 2021 @ 0722 ie wc20h 1m
10 Oct 2021 @ 1121 ie wc2d 3h 41m
08 Oct 2021 @ 0740 ie wc15h 34m
07 Oct 2021 @ 1606 wc6h 4m
07 Oct 2021 @ 10021d 3h 12m
06 Oct 2021 @ 0650 ie21h 33m
05 Oct 2021 @ 0917 ie1d 48m
04 Oct 2021 @ 0829 ie wc19h 51m
03 Oct 2021 @ 12384h 52m
03 Oct 2021 @ 0746 ie15h 5m
02 Oct 2021 @ 16416h 21m
02 Oct 2021 @ 1020 ie3h 40m
02 Oct 2021 @ 0640 ie16h 11m
01 Oct 2021 @ 14296h 18m
01 Oct 2021 @ 0811 ie14h 23m
30 Sep 2021 @ 1748 ie wc5h 45m
30 Sep 2021 @ 1203 ns~2h 24m 5h 13m
30 Sep 2021 @ 0650 ie14h 50m
29 Sep 2021 @ 16001h 58m 21h 10m
28 Sep 2021 @ 18502d 3h 14m
26 Sep 2021 @ 15367h 39m
26 Sep 2021 @ 0757 ie14h 16m
25 Sep 2021 @ 17417h 12m
25 Sep 2021 @ 1029 ie4h 6m
25 Sep 2021 @ 0623 ie1d 13h 43m
23 Sep 2021 @ 1640 ie23h 43m
22 Sep 2021 @ 1657 ns5h 38m
22 Sep 2021 @ 11191h 34m 4h 29m
22 Sep 2021 @ 0650 ie12h 34m
21 Sep 2021 @ 1816 ie6h 9m
21 Sep 2021 @ 1207 wc5h 17m
21 Sep 2021 @ 0650 ie17h 20m
20 Sep 2021 @ 13302d 35m
18 Sep 2021 @ 1255 ie3h 26m
18 Sep 2021 @ 0929 ie2h 11m
18 Sep 2021 @ 0718 ie7h 44m
17 Sep 2021 @ 23347h 42m
17 Sep 2021 @ 15522h 8m 8h 13m
17 Sep 2021 @ 07398h 40m
16 Sep 2021 @ 2259 ns16h 19m
16 Sep 2021 @ 0640 ie11h 38m
15 Sep 2021 @ 1902 ns12h 18m
15 Sep 2021 @ 0644 ie10h 15m
14 Sep 2021 @ 20291d 11h 30m
13 Sep 2021 @ 0859 ie2h 47m
13 Sep 2021 @ 0612 wc>11h 59m
12 Sep 2021 @ 1813 ie wc7h 14m
12 Sep 2021 @ 105920h 55m
11 Sep 2021 @ 14047h 48m
11 Sep 2021 @ 0616 wc14h 32m
10 Sep 2021 @ 15447h 12m
10 Sep 2021 @ 083215h 4m
09 Sep 2021 @ 1728 ie wc4h 16m
09 Sep 2021 @ 1312 ie6h 37m
09 Sep 2021 @ 0635 ns wc15h 45m
08 Sep 2021 @ 1450 ns5h 26m
08 Sep 2021 @ 0924 ns wc3h 21m
08 Sep 2021 @ 0603 ie wc15h 32m
07 Sep 2021 @ 14311h 38m
07 Sep 2021 @ 12533h 30m
07 Sep 2021 @ 0923 ns~1h 17m 15h 49m
06 Sep 2021 @ 17345h 19m
06 Sep 2021 @ 12151h 1m
06 Sep 2021 @ 1114~12m 3h 43m
06 Sep 2021 @ 0731 ns12h 42m
05 Sep 2021 @ 1849 ie5h 1m
05 Sep 2021 @ 1348~6h 59m
05 Sep 2021 @ 0649 ie9h 25m
04 Sep 2021 @ 2124 ie1h 3m
04 Sep 2021 @ 2021 wc5h 41m
04 Sep 2021 @ 1440 ie wc>1h 51m 5h 46m
04 Sep 2021 @ 0854 ie16h 20m
03 Sep 2021 @ 16341h 44m 23h 30m
02 Sep 2021 @ 170410h 4m
02 Sep 2021 @ 0700 ie17h 23m
01 Sep 2021 @ 13371d 4h 15m
31 Aug 2021 @ 0922 ie wc1d 2m
30 Aug 2021 @ 0920 ie16h 24m
29 Aug 2021 @ 16567h 3m
29 Aug 2021 @ 09531h 51m 1d 21h 55m
27 Aug 2021 @ 11585h 57m
27 Aug 2021 @ 0601 ie13h 19m
26 Aug 2021 @ 16421h 21m 3h 49m
26 Aug 2021 @ 12531h 22m 4h 57m
26 Aug 2021 @ 07563h 21m 19h 33m
25 Aug 2021 @ 12232h 24m 4h 58m

Interval Statistics

Interval Count100
Min1h 1m
Max3d 12m
Mean14h 38m
Median11h 48m

Latest Notes

Note IDStart Time (US/Mountain)End Time (US/Mountain)EntrantNote
20127 25 Oct 2021 @ 1549 --- Darcie In eruption. Marathon pool is low (well below the orange ring)
20009 16 Oct 2021 @ 2220 --- Brando Still ie at 22:20
19919 06 Oct 2021 @ 1540 06 Oct 2021 @ 1615 aferrara Off sometime in this window
19851 02 Oct 2021 @ 1340 --- Kitt B Central ent delay at Grotto
19822 01 Oct 2021 @ 0755 --- ddshepard Grotto is off
19819 30 Sep 2021 @ 1950 --- Graham End. No Rocket.
19803 30 Sep 2021 @ 1427 --- ddshepard Grotto off about this time. No Rocket major observed from about 13:45 onward
19795 29 Sep 2021 @ 1758 --- Frypan9 Eruption stopped at 17:58
19765 28 Sep 2021 @ 0650 --- Graham Off when I walked by. Quit overnight after a 28+ hour eruption.
19753 27 Sep 2021 @ 1941 --- Graham Still ie from yesterday afternoon D>28h
19738 26 Sep 2021 @ 0912 --- User34 Off, was on just a few minutes prior
19729 25 Sep 2021 @ 1548 --- Graham Central vents on. Also 1556, 1606, 1738.
19725 25 Sep 2021 @ 0812 --- Brian Off now
19631 17 Sep 2021 @ 0943 --- CrisG eruption has ended
19571 14 Sep 2021 @ 2245 --- Brando Grotto appears to be off at this time
19500 12 Sep 2021 @ 0640 --- Graham Off and having an energy push. Bijou on, pressure pool up. Yesterdays eruption didn't go on too long, 6 to 10h, but maybe enough to get a Fountain today?
19501 11 Sep 2021 @ 2000 --- Graham Still ie.
19481 11 Sep 2021 @ 1733 --- User34 Two central vents on, Grotto shutting off, central vents cycled off and on and then Grotto restarted at 1739
19352 07 Sep 2021 @ 1040 --- Kitt B Grotto ended at 1040
19330 06 Sep 2021 @ 0916 --- Kitt B Grotto ended at 0916
19322 05 Sep 2021 @ 1924 --- Graham Quit 1924, so a short duration.
19315 05 Sep 2021 @ 1258 --- Graham Central vents ie. also 1337ie and 1347, 1m before Grotto started without Grotto Fountain.
19179 31 Aug 2021 @ 2135 --- William grotto on weak, marathon pool was low at this time.
19164 30 Aug 2021 @ 1251 --- Graham Ended 1251, duration just over 3h30m. One Rocket Major near the end.
19145 29 Aug 2021 @ 1144 --- BrianR End of eruption
19155 29 Aug 2021 @ 0728 29 Aug 2021 @ 0953 BrianR Very unusual activity in Grotto complex, one of the two strangest starts I have ever seen. At 7:28 I arrived at Grotto to here it grumbling without any water splashing. I then saw the “pressure pool” was up and heard water boiling at Grotto Fountain. I then saw that Spa was in overflow with fast moving water to the river. From past observations I knew this was going to cause chaos if Grotto is trying to start. Further observation of the fountain area I saw that besides Grotto Fountain boiling at about one feet, The two vents in front of South Grotto Fountain were also boiling. Now the details going forward: 7:28-8:28 Grotto - grumbling with No water splashes or central vent activity “Pressure Pool “ - always up Grotto Fountain - continuous 1 ft boil Two vents in front of South Grotto Fountain - 1 to 4 ft continuous boiling South Grotto Fountain main pool - barely a weak 1 ft splash every five minutes Startling - 1 to 2 ft sporadic splashing (I started to check it at 8:15) Spa - continuous strong overflow without any vents on 8:28 Spa - overflow stopped, pool starts to drop 8:28-8:59 All previous described activity continues except Spa is no longer in overflow 8:59 Grotto becomes silent, Grotto Fountain stops visible boiling 8:59 - 9:39 Grotto and Grotto Fountain - in conjunction, Three Grotto grumbling (still no water splashes) and Grotto Fountain boiling up to 4 ft episodes (9:06-9:09, 9:18-9:25, 9:33-9:39) with equal amount of time of silence and not boiling between. “Pressure Pool” - always up but changing level with Grotto Fountain South Grotto Fountain front vents - one or both now boiling a few inches to 2 ft, stronger when Grotto Fountain not boiling South Grotto Fountain main vent - still very little weak one ft splashes Startling - one ft sporadic splashes more. active when Grotto Fountain not boiling Spa - only half of its pool full at 9:30 9:42 Grotto Fountain starts a boil that leads to the 9:48 eruption, Grotto silent this time 9:52 South Grotto Fountain erupts 9:51 Grotto starts to grumble, has first splash of water at 9:52, and erupts at 9:53 A minute or so later Startling had a 4 ft burst followed by a couple of 2 ft bursts about a half minute later before South Grotto Fountain flooded it. It did not erupt. Note again this activity was already in progress upon my arrival
19642 28 Aug 2021 @ 0724 28 Aug 2021 @ 1808 BrianR Arrived at Grotto knowing that a marathon eruption ended sometime in the early morning Grotto Splashes of water: 12:36 18:08 Rocket Splashes of water: 8:09-8:10 8:36 9:36 11:23 12:00 12:24 14:19 14:59 First heard Grotto Fountain water: 15:05 Grotto Fountain splashes/boiling: 17:37 18:05-18:08 Pressure Pool up: 17:08 17:36-17:38 18:05-18:08 Spa pool level and vents: See 8/22 Spa comments for definition key 7:25 — 1, LV on (north pool vent) 9:01 — 1.25 9:34 — 1.5 9:45 — 1.75 10:40 — 2 10:48 — LV off 12:01 — 2 12:50 — 2.25 13:45 — 2.25 14:41 — 2.75 15:08 — 3 15:48 — 3 16:14 — 3.25 16:42 — 3.25 17:44 — 3.5 Left area at 18:15, heard next day that 2 more Pressure Pool up cycles were seen, but was left unattended after that.
19122 28 Aug 2021 @ 0615 --- William off when I passed at this time
19101 27 Aug 2021 @ 0825 --- BrianR End of eruption Expanded comments prior to end of eruption: Arrived at Grotto 7:16 to find it i.e. Grotto Central Vents: Upper Pair 8:08-8:14 Upper Pair 8:22-8:24 Spa pool level and vents: See 8/22 Spa comments for definition key 7:17 — 7, all vents off 7:30 — 5 7:39 — 3 8:16 — 1.25 8:41 — 2
19093 26 Aug 2021 @ 1803 --- BrianR End of eruption
19091 26 Aug 2021 @ 1415 --- BrianR End of eruption
19090 26 Aug 2021 @ 1117 --- BrianR End of eruption
19061 25 Aug 2021 @ 1447 --- BrianR End of eruption
19055 25 Aug 2021 @ 0823 --- BrianR End of eruption
19045 24 Aug 2021 @ 1403 --- BrianR End of eruption After eruption observations until I left area: Grotto Splashes of water: 16:56 Rocket Splashes of water: 16:32 First heard Grotto Fountain water boiling: 15:59 Grotto Fountain splashes/boiling: 15:59-16:05 16:13-16:34 16:48-16:57 Pressure Pool up: 16:52-16:57 Spa pool level and vents: See 8/22 Spa comments for definition key 14:05 — 2 14:41 — 3, LV on (north pool vent) 15:02 — 3.25 15:17 — 3.75 15:33 —- 4.1 15:47 —- 5 15:59 — 4.1, LV off 16:16 — 3.5 16:34 — 3.5 16:58 — 4 Left area 17:00
19044 24 Aug 2021 @ 0812 --- BrianR End of eruption Expanded comments: Arrived at 7:35 with Grotto i.e. “Rocket Little Buddies”: See 8/22 Grotto comments for definition key Main, Tiny, Key 7:35 i.e.-8:11
19029 23 Aug 2021 @ 0902 --- BrianR End of eruption Expanded comments relating to the previous Spa and Grotto eruption and the lead up to the next Grotto and Grotto Fountain eruption: Arrived at 7:33 to Grotto i.e. knowing Spa was seen in eruption at 6:20, but I did not see any bursts. Spa pool level and vents: See 8/22/21 Spa comments for definition key 7:34 — 9, LV, BRV, RV all on 7:45 — RV off (south pool forward vent) 7:51 — BRV off (south pool back vent) 7:52 — LV off (north pool vent) 8:08 — 4 8:27 — 1 8:32 — 0 9:08 — 1, LV on 10:06 — 1 10:31 — 1.5 11:03 — 1.5 11:31 — 2 12:13 — 2.5 12:46 — LV off 12:56 — 3 13:31 — 3.25 13:49 — 3.25 14:21 — 3 14:52 — 3.25 15:21 — 3.25 15:49 — 3.25 16:48 — 3.25 17:36 — 3.5 18:12 — 3.5 Grotto Central Vents: Upper Pair 8:59-9:02 Grotto Splashes of water: 10:59 “Rocket Little Buddies” See 8/22/21 Grotto comments for definition key Main & Tiny 8:10 i.e.-9:02 Key 8:58-9:02 Rocket Splashes of water: 9:43 9:46 10:15-10:17 10:27 10:59 11:24 11:28 12:03 12:41 13:15 13:39 Pressure Pool up: 16:02 16:44-16:46 17:30-17:34 18:18-18:23 Grotto Fountain splashes/boiling: 16:42 16:46 17:26 17:29-17:34 17:51 17:55 18:12 18:19-18:26 Unfortunately had to leave Grotto area at 18:30 did not get to see 19:13 Grotto Fountain eruption
18991 22 Aug 2021 @ 1520 --- BrianR End of eruption Expanded details before and after eruption ended follow 10:33 — arrived at Grotto i.e. “Rocket Little Buddies” definitions: Buddy layout north to south: Tiny, Main, Key (the hole) sit at the northwest corner of Rocket and Distant sits apart of the others at the middle (west) “Rocket Little Buddies”: Main & Tiny 10:33-15:20 Grotto Splashes of water: 17:23 Rocket Splashes of water: 15:40 15:58-16:00 16:16 16:18 16:55 17:24 Spa pool levels and vents: See Spa eruption comments for definition key and info before 15:20 15:31 — 0.5, LV on (north pool vent) 16:07 — 0.5 16:26 — 0.5 16:42 — 1 17:06 — 1.5 17:28 — 1.75 17:38 — 2, LV still on Left Grotto at 17:40
18868 08 Aug 2021 @ 2015 08 Aug 2021 @ 2035 William turned off during this time.
18751 31 Jul 2021 @ 1101 --- Dan A Grotto off
18727 29 Jul 2021 @ 1343 --- SantaFe108 Eruption ended. Rocket continued to splash till 1947.
18689 27 Jul 2021 @ 1540 --- JarnoO (wc) Marathon quit between 1533 and 1540, 19h15m < d < ~19h32m
18604 23 Jul 2021 @ 1331 --- BrianR End of eruption
18594 22 Jul 2021 @ 1158 --- BrianR End of eruption
18564 21 Jul 2021 @ 1605 --- BrianR End of marathon eruption
18558 21 Jul 2021 @ 0615 --- BrianR Eruption from 15:38 yesterday is still I.e
18553 20 Jul 2021 @ 1219 --- BrianR End of eruption
18552 20 Jul 2021 @ 0630 --- BrianR Grotto is off upon my arrival in area
18531 19 Jul 2021 @ 1729 --- BrianR End of eruption
18530 19 Jul 2021 @ 1355 --- BrianR End of eruption
18529 19 Jul 2021 @ 0813 --- BrianR End of eruption
18515 18 Jul 2021 @ 1944 --- BrianR End of eruption
18514 18 Jul 2021 @ 1458 --- BrianR End of eruption
18513 18 Jul 2021 @ 1108 --- BrianR End of eruption
18482 17 Jul 2021 @ 1755 --- BrianR End of eruption
18481 17 Jul 2021 @ 1129 --- BrianR End of eruption
18385 12 Jul 2021 @ 1254 --- deanl ending after 2 rockets!
18357 11 Jul 2021 @ 1126 --- William central vents delay, high water volume in grotto.
18337 10 Jul 2021 @ 0758 --- donnielg Off at 7:58
18318 09 Jul 2021 @ 1022 --- donnielg Off at 10:22
18285 06 Jul 2021 @ 0650 --- deanl was ie at 6:50 - don't know how long
18231 01 Jul 2021 @ 1909 --- William central vents delay
18229 01 Jul 2021 @ 1856 --- William central vents delay
18230 01 Jul 2021 @ 1830 --- William central vents delay around this time, did not get exact start of vents
18114 27 Jun 2021 @ 1509 --- TheHikingDude Off at this time. Deep gurgling.
18094 25 Jun 2021 @ 2222 --- annelies8 still ie
18075 24 Jun 2021 @ 2036 --- William grotto turned off at this time after Rocket maj
18029 22 Jun 2021 @ 1953 --- CrisG still ie
18010 22 Jun 2021 @ 1457 --- CrisG still IE. bijou slowing down
17979 21 Jun 2021 @ 1412 21 Jun 2021 @ 1416 William central vents active
17944 20 Jun 2021 @ 1801 --- K.Cooper off by this time
17903 19 Jun 2021 @ 0805 --- JimS Turned off by 0805 but still steaming and splashing.
17895 18 Jun 2021 @ 2208 --- CrisG still in eruption
17892 18 Jun 2021 @ 2036 --- Craigmon99 Still in eruption
17844 16 Jun 2021 @ 0713 --- CraigC Grotto shut off
17806 15 Jun 2021 @ 1323 --- CraigC Grotto shut off
17789 14 Jun 2021 @ 1947 --- Craigmon99 Off after rocket at this time
17787 14 Jun 2021 @ 1806 --- William steam in the area, near start... probably grotto?
17766 14 Jun 2021 @ 0905 --- CraigC Grotto shut off between 0845 and 0905
17756 13 Jun 2021 @ 2004 --- K.Cooper (wc) Grotto still ie at this time
17748 13 Jun 2021 @ 1614 --- CraigC Grotto shut off
17715 12 Jun 2021 @ 1443 --- CraigC grotto off
17696 12 Jun 2021 @ 1003 --- CraigC central vents splashing
17688 12 Jun 2021 @ 0722 --- CraigC Grotto shut off
17678 11 Jun 2021 @ 0843 --- TheHikingDude Grotto off, no sign of water on the entire platform. Calm as can be. Spa was 2 feet below the rim.
17654 11 Jun 2021 @ 0713 --- CraigC good energy cycle in Grotto, water barely visible in pressure pool at Grotto Ftn
17652 11 Jun 2021 @ 0638 --- CraigC marathon pool about 8 inches down
17590 08 Jun 2021 @ 1700 08 Jun 2021 @ 1835 annelies8 No eruption between these times that I saw, although from 1725 on I was dividing attention between this and Riverside. Not sure if it hasn't gone yet or I missed it earlier.
17541 07 Jun 2021 @ 2058 --- Craigmon99 still ie
17505 06 Jun 2021 @ 1128 06 Jun 2021 @ 1210 Polly Grotto marathon end sometime between 1128 and 1210.
17498 06 Jun 2021 @ 0630 --- CraigC Grotto ie., Marathon Pool appears about 4 inches below high water mark
17470 05 Jun 2021 @ 0850 --- CraigC Grotto off, observed from F&M
17243 29 May 2021 @ 0000 --- JarnoO (wc) Marathon continued overnight; Overnight captures: 0025, 0100, 0157, 0256. May have quit somewhere between 0256 and 0615. At first glance only passive steam rising at the latter time.
17232 28 May 2021 @ 1940 --- Ben VL Still IE when I left for Grand at this time.
17228 28 May 2021 @ 1300 --- JarnoO (wc) Marathon. Still ie 1300 (as well as seen ie somewhere around 1145), 1420, 1500, 1600, 1725, 1809, 1856, 1950. Daytime & overnight captures: 2100, 2200, 2300.
17224 28 May 2021 @ 0954 --- gobysmith still in eruption
16819 23 Jan 2021 @ 0954 --- RangerRebecca Grotto off but emitting steam. Audible thuds or thumping; like steam bubbles collapsing in an empty chamber.
16808 13 Jan 2021 @ 1501 --- JarnoO (wc) ie at this time; not known if continuation of 0849ns
16500 03 Nov 2020 @ 1206 --- TheHikingDude Grotto appears off at this time.
16472 28 Oct 2020 @ 1412 --- Janet Jones Off. No steam rising or water heard. Steam rising in Grotto Fountain, but hard to see any water level.
EntrySourceLinkComment
18 Aug 2020 @ 1452 JSJ https://www.youtube.com/watch?v=L4pz9gWnQwk Video by Craig Corless showing the start of Grotto Geyser's 2:52 PM-onward eruption on 18 August 2020, with both Grotto Fountain Geyser & South Grotto Fountain Geyser erupting in the background.
03 Oct 2019 @ 1526 EricZ https://www.youtube.com/watch?v=YpsAVShVyxs&feature=youtu.be Grotto Start
15 Aug 2018 @ 0941 JSJ https://www.flickr.com/photos/jsjgeology/32563168958 Photo of initial runoff (approaching Variable Spring) from Grotto Geyser's 9:41 AM-onward eruption on 15 August 2018.
15 Aug 2018 @ 0941 JSJ https://www.flickr.com/photos/jsjgeology/44618689690 Photo of Grotto Geyser's 9:41 AM-onward eruption on 15 August 2018.
14 Aug 2015 @ 1314 JSJ https://www.flickr.com/photos/jsjgeology/21145226344 Photo of Grotto Geyser's 1:14 PM-onward eruption on 14 August 2015.
08 Jul 2014 @ 1430 JSJ https://www.flickr.com/photos/jsjgeology/15106150617 Photo of Grotto Geyser erupting during the mid-afternoon of 8 July 2014.
Baseline does not exist.