A SNAPSHOT OF THE DYNAMIC NORRIS GEYSER BASIN HYDROTHERMAL SYSTEM IN 2018
This study collected pH, temperature, specific conductance, and high-precision location data on 916 thermal features in Norris Geyser Basin during the summer of 2018. During the same time period, the World’s largest geyser, Steamboat, erupted a record-setting 32 times (the previous record was 29 eruptions in 1964). Concurrently, tectonic faults ~25 km west of Norris Geyser Basin at Maple Creek experienced a swarm of increased seismic activity. There was also above average snow water equivalent and total precipitation in 2017-2018, as well as discharge of Tantalus Creek during April-June 2018. The inventory of Norris thermal features in 2018 captures a snapshot of the hydrothermal system during this unique period.
The pH of 75% of Norris thermal features were between 2-4 (pH 2-3=28.3%; pH 3-4=46.7%), maintaining Norris’ position as one of the most acidic basins. Specific conductance correlates with the concentration of dissolved geothermal solutes and is highest in the lowest pH features. The median value was ~2000S/cm with 95% of features above 1000S/cm, confirming a strong influx of geothermal water to the majority of Norris features. Comparing 2018 data to a 2007 inventory show that 79% of features decreased in specific conductance, 60% increased in temperature, and there was no change in pH. We speculate that the hotter temperatures in 2018 relative to 2007 may reflect a more direct and voluminous connection between deep magmatic hydrothermal waters and the shallow meteoric system that experienced both greater mass and heat exchange in 2018, possibly augmented by the seismic and deformational unrest. Statistical analysis has the potential to further probe the possible connection between increased precipitation, subsurface unrest, and hydrothermal system changes.