Jet dynamics at Lone Star Geyser, Yellowstone National Park

Geysers provide a natural laboratory to study multiphase eruption processes and the geophysical signals that can be measured before, during, and after an eruption. As part of a field study at Lone Star Geyser, Yellowstone National Park in September, 2010, we recorded multiple consecutive eruptions with visible and infrared video and an audio microphone. These measurements, along with water discharge measurements in outflow streams, allow us to constrain eruptive liquid and steam volumes and calculate aspects of jet dynamics and energetics . We perform Particle Image velocimetry (PIV) analysis of high-speed visible video images to extract maximum jet velocity and height throughout an eruption. We find that the time and frequency domain structure of maximum velocity is similar to that of median jet temperature and amplitude of acoustic emissions. We correlate visible and infrared video to estimate the mass fraction of steam versus liquid throughout an eruption, and use this to calculate an energy budget for the geyser. The clear transition from liquid to steam dominated flow during eruption is mirrored in the frequency domain, likely reflecting a shift in the sound speed of the mixture and a transition towards choked conditions during eruptions. However unsteadiness in the flow implies that this condition is not always met.