With 2021 at an end, a look back on Steamboat Geyser in Yellowstone National Park shows a significant decline with only 20 major water eruptions, which is far fewer than the 48 eruptions in each of the preceding two years. The reason for the slowdown remains a mystery as is the reason it became so active two years ago.
During the year, the Yellowstone Volcano Observatory reports 2,773 earthquakes were located in the Yellowstone region, which is consistent with typical background levels of seismicity, which is on average, about 1500–2500 earthquakes every year.
During December, the Yellowstone Seismic Network detected only 43 earthquakes in the park. The largest tremor being a minor quake of 2.6 magnitude centered north of Pahaska Tepee.
No earthquake swarm activity was observed in Yellowstone during December.