Conduit Processes at the Haukadalur Geyser-Hosting Hydrothermal Field (Iceland) Revealed by In Situ Temperature and High-Speed Camera Measurements

• Published in: Journal of Geophysical Research: Solid Earth
• Main Authors: Collignon, Marine, Pioli, Laura, Trippanera, Daniele, Carrier, Aurore, Lupi, Matteo
• Other Authors: Physical Science and Engineering (PSE) Division, Earth Science and Engineering Program, Department of Earth Sciences University of Geneva Geneva Switzerland, Department of Chemical and Geological Sciences University of Cagliari Cagliari Italy, ADRGT Grenoble France
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Geophysical Union (AGU) 2023
• Subjects: Iceland
• Online Access: http://hdl.handle.net/10754/695241; https://doi.org/10.1029/2022jb026140

Geysers fascinate scientists and visitors for several centuries. However, many driving mechanisms such as heat transfer in the conduit and in the subsurface remain poorly understood. We document for the first time transient temperature variations inside the active Strokkur's and nearby quasi-dormant Great Geysir's conduits, Iceland. While recording temperature inside the conduit, we visually monitored Strokkur's activity at the vent with a high-speed camera, providing a high temporal resolution of the eruptions. Our results reveal heat transfer from a bubble trap to and through the conduit. We propose a model for the eruptive cycle of Strokkur that includes vapor slug rise, eruption, and conduit refill. Each water jet of an eruption is marked by an initial pulse of liquid water and vapor, emitted at a velocity between 5 and 28 m/s and generally followed by a second pulse less than a second later. The timing of eruptions coincides with temperature maxima in the conduit. After the eruption, the conduit is refilled by water falling back in the pool and drained from neighboring groundwater-saturated geological units. This results in a temperature drop, the amplitude of which increases with depth while its period is reduced. This reflects faster heat transfer in the deeper than shallower part of the conduit. The amplitude of temperature drop following an eruption also increases with the eruption order, implying larger heat release by higher-order eruptions. Temperature in the conduit subsequently increases until the next eruption, starting then a new cycle. We thank the Umhverfisstofnun, the Environment Agency of Iceland for the research permit at the Haukadalur hydrothermal field, and the park rangers for their support. O. Rögnvaldsson and G.N. Petersen are thanked for providing information about weather data. This study was partially funded by the Augustin Lombard Scholarship for S. Mueller, who is also thanked for his support in the field. We are grateful to G. Carrier for her help in the field and A. Mazzini ...