Update: 2018 May 30 11:00 Added some more observations on the eruption. Will probably add more later, along with fixes for typos and bad grammar.
As we rounded the curve beyond the interchange at about 21:35, Suzanne and I could see Grand erupting. It was almost dark. That would be the last Upper Basin activity we would see until Monday, when we would also finally see the Old Faithful area in daylight.
Over the past few weeks I've been running my AppleTV GeyserLog app in a simulator on my computer's second screen. Mostly as inspiration for the upcoming Yellowstone visits, but also to see how the app is behaving. Got to see the start of a Giant eruption that way earlier this month, and since then all the reports of Giant bathtub events.
So wasn't too surprised to see the YVO report of something happening at Norris a week ago on Friday night. The last few intervals had been around a week, which fit perfectly. Sure there wasn't much data to go on, but this activity, at this distance, reminded us of the activity of 1982-- a sudden winter start, quickly becoming regular about one a week or so.
The problem with that was in 1982 the regularity stopped just as suddenly when there were disturbances in June. The later eruptions in early August and early September required more than looking at the calendar. So as the confirmations came in, it became apparent to Suzanne and I that we were going to be spending a lot of time at Norris during our annual Memorial Day visit. Seize the opportunity to see Steamboat while it was still sorta predictable and regular, as it might not be that way when we will be back in July.
We left Satuirday morning while still dark and arrived at Norris so early that the front rank of the parking lot was completely empty. Arrived at the lower platform at 05:30 and began my first Steamboat wait since 1982. That was over 4 continuous days of waiting for nothing to happen. I finally gave up two days before my vacation ended and headed back to the Upper Basin so I could see something erupt. Steamboat erupted two days after I left for home.
According to my notebook, I left the platform twice over the next 15-1/2 hours. Since Steamboat has no known precursors or indicators, it's hard to leave, especially if seeing the start from the parking lot isn't good enough. The weather forecast said cloudy and cool, but it turned out to be mostly sunny. There was one minor rain-shower scare in the evening, but we didn't encounter any real rain until the drive south of Madison Jct.
I tried setting up an old phone as a camera on a tripod and just letting it run, but after 40 minutes, I'd exhausted half the battery. That wasn't going to work, so I just left the camera pointed at the feature and tried to quickly start it when something interesting happened. That had mixed results, because between the reaction time and the number of button presses need to start recording, I often missed the best part.
As evening approached, we had to start making decisions. We almost left before sunset because of a rain shower. By then the activity had been pretty calm for hours, and based on what we'd seen in previous 1980s sits, we weren't encouraged. An hour after a small surge we decided that we'd had enough and needed to risk heading back to Old Faithful for a few hours of sleep.
Fortunately, we avoided all the traffic problems. During the day a herd of bison were migrating up along the Madison and that was causing mile long backups. As it was, when we arrived at Madison Jct. around 2130, the backup to make the left turn from Old Faithful to West Yellowstone was to the big curve above Firehole Canyon Drive entrance.
The next morning it was a relief to look at GeyserTimes and see no reports, and then to not see a huge steam-cloud as we exited the Gibbon Canyon. We arrived back at Norris at about the same time as the previous day, to the same conditions. The minor play from Steamboat seemed more vigorous, but also knew by then that that was subjective.
The day pretty much proceeded like the previous one. It was actually much nicer than we'd expected, as the weather forecast was calling for showers in the morning, which never occurred. The wind was blowing the steam and spray right toward our platform most of the day. But in the afternoon, the clouds built up, and by 18:00 it was starting to rain. I was in the parking lot at the time, and had to quickly get back to the platform where my rain-gear was still in the pack.
That's when the fun began. Around 19:00 we had another nice, large surge. I'd been noting these on Saturday, but not on Sunday. I wanted to read instead. When the next surge came quickly, I was at least able to record it. As the video shows, these subsequent ones came at around 19:06, 19:08, and 19:12 according to my phone's clock. This was the first time they'd come that close together, and so many of them, too.
But not only that, the activity between the surges seemed stronger. A totally subjective observation, but it really did seem like the geyser had tired of jerking us around and was now going to reward us.
After the third surge, I realized that it might be useful to alert those in the parking lot that something different was happening. My radio was buried, but Linda Strasser was able to make a quick report that enabled a few people to at least be headed back when the eruption began. In future waits, I think it important to announce these surges. It may be Guru Geyser Gazing to think they matter, but we haven't much else to go on. If nothing else, it will give people a heads up and that it's time to at least pay attention to that direction and maybe start getting ready to run.
As the video shows, the fifth surge got big fast, and stayed that way. Unlike the previous ones, I didn't catch the dying moments, but instead it was continuing to build. It seemed obvious that this was different, and the video shows that. With 15 or 20 seconds, there was no doubt that we were at least going to see one of the USGS's "minor major" eruptions. (More on that later.)
The first minute or so the water columns for both vents were white, but then the North Vent turned a rusty brown and started throwing rocks. I'm assuming that's how long it takes for the runoff on the slope to turn into a flood and start getting kicked back up. I think the buzzword is "sustainable." It took about a minute for the dry runoff channel in front of the platform to fill with water the color of glacial runoff.
The water phase lasted much longer than I expected, and was much louder, too. On the platform shouting was required if you wanted to say anything. When the steam phase transition began, it got even louder. I could feel the platform vibrating through my feet. The North Vent water steam column was white again.
Around this time, the wind finally shifted so that the platforms were getting doused by the condensation from the stem plumes. This rainfall was gritty and milky. It would be interesting to find out if that is because of the chemistry of the water, or because of fine particles being washed into the vent and ejected up with the steam cloud.
The colors and heights of the water column also kept changing. In the early part of the water phase it seemed that the South Vent was the one more likely to be brown, while later it was the North Vent that was a rich brown. Approaching the time of the transition to steam, it also seemed like the North Vent was no longer a continuous jetting to great height, but was bursting as if the water was trying to force its way through a pool of water. (To use the obvious cliché, think Grand.)
I suspect all this is not due to any deep activity, but because of water washing back into the vents. Behavior which is dependent on the amount of water and the wind direction, As the transition begins, the water supply decreases and stops blocking the vents. The same for the start, at first there's little to no water washing downhill from the north and east, so both columns are tall, continuous and clean.
What I wonder about is the source of all the grit we experienced during the steam phase. Is it from down deep, or more of the stuff washing in? I want to suspect it's the latter. Note that the mound between the vents and the platform is eroding away, exposing small bounders cemented in place by white material. It wouldn't surprise me to learn that this cement is the grit. (Suzanne has some thoughts about the changes in the formations since the 1980s that she plans to publish soon.)
The eruption came at a perfect time, considering the other possibilities. Because it was shortly after a rain, most people were fairly well waterproofed, more than if it had erupted a few hours earlier. Once the eruption started, I would not have wanted to be digging around in my pack for what I needed. (Or frantically shoving things into the pack to keep them dry.)
It wasn't that cold or damp either, so most of the time the eruption wasn't obscured behind fog and mist. It was long enough before sunset so that the entire water phase and the first hour of steam were easily visible. We left as it started getting dark, and didn't feel like we were being cheated.
After we returned to the Old Faithful area, it was time for a celebration and to view our videos. The Bear Pit was an ideal location, as our noisy videos wouldn't disturb our cabin neighbors. As we returned from there, just after midnight, Old Faithful erupted. We gave it the attention we normally do, and kept on walking, despite it being the only other geyser we'd seen since we woke up.
The next day I did a quick run down the basin to take a look at the Giant platform. I got a three minute Bijou pause for my efforts. Grand did not erupt before the time we'd decided to leave, but it did manage to erupt as we were about to leave the parking lot.
There were some differences between the activity during the wait and what I saw 36 years ago. Most notable was the amount of water being put out. Back then, the only time we saw any discharge down the runoff channel was after a superburst or similar large surges. This time the flow down was continuous, with frequent surges from even minor South Vent activity.
There never really was any progression of function as we saw back then. In the half hour leading up to the eruption, I was watching the activity, which as almost entirely South Vent surging. Even between the big surges, which were the only Combined function I remember seeing. (And the first surge may even been a South function.)
Even so, there were times when it could be felt that the activity was higher or lower than normal. We managed to escape several times for food and pit breaks and only once did we miss any sort of surge event.
When does an eruption of Steamboat start? As the video shows, there's not a point where it suddenly bursts up and you can say, "this is it". It just keeps climbing. Suzanne and I agreed that it's the start of the surging. Use the same procedure as used for timing Old Faithful. If the surging doesn't turn into an eruption, you just click the stopwatch. If it does, then you have your start time. The video clip of the eruption starts at 19:15:57, after the surging had started.
One thing that really bothered me is hearing about the attitude of the YVO professionals concerning Steamboat. It appears that they are either not doing a good job of explaining what is going on, or they are passing around bad information. They are also basing way to much of what they say on instrument readings. Readings they have never seen before, and therefor have no idea what they actually mean, other than, "something different" happened. The proper interpretation would be "we don't know, yet,", instead we were getting talk like "minor major event" and water phases that only lated a minute or two.
I pointed out on several occasions that there was no way that statement could be made. Until the start of an eruption, and the subsequent start of water phase were witnessed, they just didn't know what happened. You can't interpret the size of the activity based on erosion or runoff because that is weather and wind dependent. (For example, the parking lot didn't get drenched.)
I also see that they put out info that the eruption started at 19:33. From direct observation we know that's when the transition to steam started. Now that they have some information they can use to interpret their seismograph traces they need to correct that start time, and add disclaimers to the other start times. (Like adding "ie" to them.) I will be pleasantly surprised if they do that any time soon.
Update: 2018 Jun 01 I noticed that the video has been linked by at least one non-gazer site. Those people seem put off by the screaming, and have the need to display their feeble wit in action. So on the hosting site I added, for me, a polite response:
I've noticed that some people linking to this feel a need to comment on the screaming. Let me put it mildly-- Those weren't tourists screaming. You commenters are the tourists. I didn't post this video for you. I posted it for those people who did the screaming (and there were quite a few) and for those people who wanted to be there adding to the screaming. If you don't understand why those people couldn't contain their enthusiasm, then please, stay away and leave the place for people who do.