Yellowstone Caldera Chronicles is a weekly column written by scientists and collaborators of the Yellowstone Volcano Observatory. This week's contribution is from Michael Poland, geophysicist with the U.S. Geological Survey and scientist-in-charge of the Yellowstone Volcano Observatory..
Most people will agree that 2020 was an unforgettable year, but not necessarily in a good way. At Yellowstone National Park, however, it was business as usual. Earthquakes, ground deformation, geyser eruptions — a “typical” year for America’s first national park. It was also an important year for highlighting the value of scientific research in Yellowstone. After all, it was a thermal bacterium — Thermus aquaticus — discovered in a Yellowstone hot spring in 1966 that became the basis for the PCR technique that has been widely used to test for the COVID-19 virus.
Overall, seismicity in the Yellowstone area during 2020 was distinctly normal. There were 1,718 earthquakes located in the region, which is on the low side of the average 1,500–2,500 events per year. In fact, 2020 was the third year in a row with less than 2,000 located earthquakes.
The largest earthquake of the year was a three-way tie, with M3.1 events occurring in March, May and November, all in the area between Norris Geyser Basin and Hebgen Lake. There were also 23 swarms of earthquakes in Yellowstone during 2020, accounting for about 50% of the total number of located earthquakes — also typical for the region.
Despite the lack of noteworthy seismicity in Yellowstone, there were a couple of significant earthquakes in the region — a M5.7 event just west of Salt Lake City on March 18, and a M6.5 event in central Idaho on March 31. Both earthquakes were related to a slow extension of the Basin and Range province in the western United States and had nothing to do with Yellowstone. Nevertheless, YVO answered many questions from concerned citizens who feared the earthquakes were related to the volcanic system or might trigger activity.
There were no major changes in ground deformation during the year. The caldera continued to slowly subside at rates of 2–3 cm (about 1 inch) per year, as it has since 2015. And there was no noteworthy deformation recorded at Norris Geyser Basin — a period of calm following uplift in 2015–2018.
Steamboat geyser, in Norris Geyser Basin, continued to amaze and delight visitors with 48 water eruptions in 2020, matching the record set in 2019 for the number of eruptions in a calendar year. And just like last year, the shortest and longest time periods between eruptions were about three and 17 days, respectively.
Also, Giantess Geyser, near Old Faithful, burst to life in August and September for the first time in six years. Prior to 2011, the geyser erupted a few times every year before going largely quiet (except for one eruption in 2014). Perhaps Giantess is returning to a more active phase.
Because of the COVID-19 pandemic, YVO scientists were unable to do a lot of the work that had been planned — including the biennial coordination meeting, scheduled for May, that brings all YVO scientists together for a few days to discuss research and make future plans. Critical maintenance and field experiments were still completed, but many YVO scientists spent time in their home offices completing research projects. The result was a flurry of publications highlighting fascinating aspects of Yellowstone.
For example, scientists studying Old Faithful were able to analyze wood fragments embedded in the geyser cone — evidence of a time when the geyser must have been dormant, because trees don’t grow on active geysers. The study dated the wood fragments and concluded that Old Faithful did not erupt between about 650 and 800 years ago, probably due to a severe regional drought that also had a tremendous impact on indigenous cultures in the Southwest.
The Yellowstone Volcano Observatory also had some big news to share in 2020. Montana State University became the ninth member of the YVO consortium. MSU brings a wealth of experience in the geology of the Yellowstone region, as well as the characteristics of thermal-biological interactions in the park’s geyser basins. In addition, the Wyoming State Geological Survey, one of the YVO member agencies, released an online digital map of Yellowstone, with a tremendous catalog of available information, including topography, geology, hydrology, earthquake locations, monitoring stations, sample sites, and other datasets. You can explore that resource yourself by going to the Wyoming State Geological Survey website (https://www.wsgs.wyo.gov/) and click on “Yellowstone Geology” under the “Interactive Maps” section.
All in all, it was another interesting year at Yellowstone. Even so, no one at YVO is sorry to see 2020 pass into the rearview mirror. As 2021 dawns, we will continue to monitor activity in Yellowstone National Park and report findings and noteworthy activity in future editions of Yellowstone Caldera Chronicles. Stay tuned.
From all the members of the Yellowstone Volcano Observatory consortium, take care, be safe and best wishes for 2021.