Controls on Geyser’s Eruption Behavior by Numerical Modeling

Geysers are natural hot springs that intermittently erupt with a mixture of water and steam. Geyser eruptions cause hazards but are also valuable resources for potential green energy. Additionally, geyser eruptions share similarities with volcanic eruptions in heat transfer and subsurface fluid dynamics, making them useful analogs for understanding volcanism and aiding hazard mitigation. However, significant gaps remain in our understanding of geyser behavior, particularly regarding the irregular eruption patterns observed in complex geysers like Steamboat. This research aims to address these knowledge gaps by investigating the behavior of geysers with different architectures and heat inputs. To achieve this, we simulate geyser eruption cycles and investigate the factors influencing their periodicity and the evolution within their eruption cycles.

We explore the sensitivity of eruption intervals to a range of geological and thermal parameters, including porosity, the permeability contrast between the geyser conduit and the surrounding rock matrix, basal heat flux, and conduit dimensions (radius and depth). Our results indicate that variations in basal heat flux can influence eruption style and, consequently, periodicity. We classify the observed eruption styles as "regular" and "long-period" geysers, based on the eruption duration and interval reflected in the evolution of the steam saturation profile within the conduit. Changes in permeability and porosity affect the eruption interval, with permeability demonstrating a particularly significant control over periodicity. Conduit dimensions, however, show no significant impact if the heat flux in the unit area unchanged. We compared the observed time intervals from the Steamboat geyser to our model results. The results indicate that the permeability change may reawaken the eruptions at Steamboat since 2018.

Additionally, we analyze the evolution of key parameters within the eruption cycle, including the migration of the boiling front, water and steam mass flux, pressure, and temperature in the conduit. The evolution of those parameters is consistent with the observations from Steamboat providing insights into the pre- and post-eruption dynamics, offering clues about the triggering mechanisms of Steamboat’s eruptions. This research contributes to a refined understanding of the complex interplay of factors governing geyser behavior, potentially offering insights into the dynamics of more complex real-world geysers such as Steamboat.