Yellowstone Volcano Update for August 2021
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.