Steamboat Geyser has been delighting visitors to Yellowstone National Park since March 2018. Seismic surveys of the geyser and the nearby Cistern Spring are now revealing details of the hydrothermal plumbing system that would otherwise not be known and may explain why the geyser eruptions are the highest in the world!
With all eyes on the spectacular eruptions of Steamboat Geyser, it is easy to lose sight of the fact that the cistern spring about 300 feet away gradually drains a few hours after the amazing Steamboat water show. In the 24 hours after the steamboat erupted water, the cistern spring empties, only to refill within a few days and restore the normal water level. This pattern has been around since the 1960s and continues into Steamboat’s current active phase, which began in March 2018.
Indeed, it is not uncommon for individual hydrothermal features to be related in time. A good example is the beehive geyser near Old Faithful in the upper geyser basin – spectacular beehive eruptions always occur a few minutes after activity on a smaller adjacent “indicator” vent. It is believed that these types of compounds are a reason for the regularity of some eruptions, as the hydrothermal features underground can compete for water and heat resources. For the most part, however, features that appear to be related, such as the beehive geyser and the beehive indicator, are right next to each other (often within 10 feet). In contrast, the Steamboat Geyser and Cistern Spring are a lot further apart – about 330 feet! This raises questions about the underground aqueduct. How are steamboat and cistern connected? And does the sanitary geometry influence the eruption dynamics and regularity of the Steamboat Geyser?
To seek answers to these questions, the University of Utah, in partnership with Yellowstone National Park, installed seismic arrays around Steamboat Geysers and Cistern Spring Seismic Arrays in the summer of 2018 and 2019, providing a non-disruptive way to determine the seismic source passing through Bubble formation and collapse occurs when the system is charged. This can enable four-dimensional views of the subterranean hydrothermal plumbing system.
The work recently published in the Journal of Geophysical Research found that the steamboat and cistern installation structures extend to a depth of at least 450 feet, which is much, much larger than what was previously found at Old Faithful (~ 260 feet)! The pipe of the steamship is approximately vertical to 400 feet deep. Surprisingly, cistern piping includes a shallow vertical conduit that connects to a deep, large, offset reservoir located about 60 meters southeast of the source. More interestingly, there is no direct connection between the steamboat and cistern that can be mapped in the top 400 feet. This indicates that the two systems are likely connected by a network of cracks rather than “open pipes”.
From recent multidisciplinary work at Steamboat and other geysers, it has become clear that deeper storage of energy in the plumbing system can lead to more powerful (and larger) eruptions. This could explain the origin of the impressive Steamboat eruptions – it’s the tallest geyser in the world, after all. However, there is still little understanding of the role of the large reservoir associated with the cistern and whether this structure affects the Steamboat Geyser eruptions. Understanding these relationships requires a more detailed study of the fluid and heat transfer within the fractured subsurface medium.
With campaign-style seismic operations, scientists can only record signals within a short window of time. These results provide a basis for a better understanding of the system, but the question remains: what is the nature of the seismic sources when Steamboat is in a less active phase? And how could continuous monitoring be used to better understand the steamboat cistern system? Hopefully future experiments will give even more insight into Steamboat’s spectacular eruptions and its fascinating relationship with Cistern Spring!
This story first ran in the daily newspaper Montanan. Yellowstone Caldera Chronicles is a weekly column written by scientists and staff at the Yellowstone Volcano Observatory. This week’s contribution comes from Sin-Mei Wu, Jamie Farrell, and Fan-Chi Lin, seismologists at the University of Utah Seismograph Stations and the Department of Geology and Geophysics.
Comments are closed.