Yellowstone Volcano Update for August 2021

Video Transcript

Detailed Description

Yellowstone Volcano Observatory scientist-in-charge Mike Poland tells the story behind the color change of Morning Glory Pool and shows how to recognize seasonal changes in ground deformation data in this September 1, 2021 video update of volcano and earthquake activity at Yellowstone Volcano.

Morning Glory has a cautionary tale to tell about how humans can impact the way thermal features look and behave. Morning Glory was a beautiful, deep blue color (it was named after the flower). But the pool was right next to the road that came into the Old Faithful area so it was heavily visited. People would throw things into the pool, like rocks, coins, and handkerchiefs. This clogged the thermal input to the pool, lowering its temperature. Thermophilic bacteria began to occupy different parts of it of the pool, and the pool lost its deep blue color. Efforts to clean it out helped, but the color of the pool has never returned to that beautiful blue.

For earthquakes, August saw a return to background levels of seismicity with just 97 located earthquakes. The largest was a Magnitude 3.1 west of the Norris Geyser basin. There was a little seismicity beneath Yellowstone Lake in the area of July's earthquake swarm, but none of the activity in Yellowstone during the month of August qualified as a swarm (occurring in a short period of time in the same area) and earthquakes in this area are likely aftershocks.

Seasonal changes appear in ground deformation data. The trends at the White Lake and Mallard Lake GPS stations have been subsidence of just a few centimeters (an inch or two). But every summer, there's an interruption in that subsidence pattern. Water percolates down and the subsurface soaks it up like a sponge. This appears in the data as a bit of uplift or a pause in subsidence. This has been occurring every summer, and we see it again this summer, in 2021.

Steamboat Geyser, the largest geyser in the world, has gone an entire month without a water eruption. There has been a recent increase in minor activity that may lead to a water eruption soon, but overall it appears that Steamboat activity is waning and the geyser may go dormant again.​​​​​​

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Length: 00:06:30

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Transcript

Hi everybody, I'm Mike Poland, the scientist in charge of the Yellowstone Volcano Observatory and this is the YVO monthly update for September 1st of 2021.

Coming to you today from the Upper Geyser basin in Yellowstone National Park, not far from Old Faithful, and this is Morning Glory Pool in the background behind me. And Morning Glory has a sort of a cautionary tale to tell about how humans can impact the way thermal features look and behave. Morning Glory used to be a beautiful, deep blue color, of course named after the flower, but it was right next to the road that came into the Old Faithful area so it was very heavily visited. And people would have a tendency to throw things into the pool, rocks, coins, handkerchiefs, all kinds of random things. In fact, the pool earned the nickname "The Garbage Can" for a while, there was so much stuff that was thrown into it. And in fact this clogged the input, the thermal input to the pool, and that resulted in the pool lowering its temperature and thermophilic bacteria began to occupy different parts of it. So the plumbing of the pool changed and that changed the color from that deep blue to this sort of colorful pattern that we see today.

Now in 1970s, the Park actually siphoned out some of the water and cleaned up some of the garbage. They pulled out something like $90 in change, over$86 in pennies alone, as well as over 70 handkerchiefs, all kinds of things like that. And then of course when they let the water back in, it never really came back to that nice deep blue Morning Glory color. So an unfortunate tale about how humans can alter these thermal features just by throwing things in. And that's of course why that's not something we do here in Yellowstone.

Okay. Well, now let's talk about what happened during the past month in terms of volcano and earthquake activity in the Yellowstone area.
For those of you that follow Yellowstone seismic activity, you know that it's been a pretty busy summer. There were a lot of earthquakes located in June and July, especially July when there were over 1000 earthquakes that were located. And that is the most number of earthquakes since June of 2017 when there were over 1100 that were located. Well August saw a return to background levels of seismicity. The University of Utah Seismograph Stations, they're responsible for the operation and maintenance of the Yellowstone seismic network, located just 97 earthquakes during the month of August. The largest was a magnitude 3.1 here just to the west of the Norris Geyser basin. And this occurred on August 20th. Now this region between Hebgen Lake and Norris sees most of the seismicity in the region. So it's no surprise that that largest earthquake, a small earthquake M3.1 occurred in that area. There was a little bit of seismicity beneath Yellowstone Lake. This is in the area of July's rather large swarm, but none of the activity in Yellowstone during the month of August qualifies as a swarm. And that's because none of it occurred in a short period of time all in the same place. So a smattering of earthquakes, sort of aftershocks from the swarm that occurred in July, but no swarm activity in the Yellowstone region during the month of August.

We didn't see any changes in deformation in the Yellowstone region. It's been pretty steady over the past several years. This is GPS station at the White Lake area that's on the Sour Creek resurgent dome in the east part of the caldera. Vertical deformation over the last two years with each one of these blue dots indicating the day. Downward trends indicate subsidence and upward trends indicate uplift. Now over the past couple of years, we've seen overall subsidence of just a few centimeters, an inch or two. Now every summer, there's a bit of an interruption in that subsidence pattern. You can see here during the summer of 2020, and again during the summer of 2021. And that's caused by groundwater that percolates down into the subsurface and the surface sort of soaks it up like a sponge. And we get a little bit of uplift or a pause in that subsidence. So that's what's occurring every summer and we're seeing it again in the summer of 2021. It's the same story on the other side of the caldera, the west side of the caldera and the Mallard lake resurgent dome. This is a GPS site near Old Faithful. Again, the last two years, and each one of these blue dots is one day. There's this overall subsidence trend, but we can see over the past summer, we've seen a pause in that subsidence, perhaps even a very slight amount of uplift, maybe just a centimeter, just a fraction of an inch, due to all that groundwater from snow melt that's percolating into the subsurface. The signal over the past year has gotten a little better at this site because a fire in 2020 resulted in a thinning of the trees in this area. And it was done intentionally to reduce the fuel load near Old Faithful. And that resulted in a better signal reaching the GPS antenna and so a cleaner data set. And finally moving over to the Norris Geyser basin. We haven't seen any changes in the last year and a half or so. And Norris had been going up from 2015 to 2018. It didn't do too much from 2018 to 2019, a little bit of subsidence here right at the end of 2019 but since early 2020, Norris has been very steady, no real up or down motion in the Norris area. So Norris remains quiet.

And then turning to everyone's favorite Geyser in the Norris Geyser basin, Steamboat Geyser, the largest geyser in the world. It went an entire month without an eruption. And what you're seeing here is the temperature measured in the Steamboat outflow channel. And these variations here are just daily variations. It gets warmer during the day and cooler overnight. So no real activity to speak of during these time periods where the temperature is just going up and down with the temperature of the day. Toward the middle and end of the month, we see more of this kind of spiky behavior. And this is caused by an increase in minor erupt activity at Steamboat Geyser. We tend to see an increase in minors before there is a major eruption. So this may suggest we're on the road to another major eruption, the last one was on July 8th. So it's been well over a month, month and a half, possibly even two months by the time we get one. This is in stark contrast the previous few years when we had major eruptions every five to 10 days or so. And it really suggests that Steamboat activity is waning. It may be going dormant again soon, but perhaps not quite yet. This minor activity suggests we may be on our way to a major eruption sometime in the month of September.

Well, that does it for the monthly update. Now, remember if you have any questions, you can email us anytime at yvowebteam, that's all one word, @usgs.gov. Stay safe, stay healthy, and we will see you next month. Take care.