Abstract
Here, we report on a new geyser (named Shaman) formed in the Uzon caldera (Kronotsky Federal Nature Biosphere Reserve, Russia) in autumn 2008 from a cycling hot Na-Cl spring. The geyser is a pool-type CO2-gas lift driven. From 2012 to 2018, the geyser has shown a rather stable interval between eruptions (IBE) from 129 to 144 min with a fountain height up to 4 m, and the geyser conduit has gradually enlarged. In 2019, the Shaman geyser eruption mode significantly changed: cold water inflow from the adjacent stream was re-directed into the geyser conduit and the average IBE decreased to 80 min. We observed two eruptive modes: a cycling hot spring (June 2019) and a cycling geyser (after June 2019). Bottom-hole temperature recording was performed in the geyser conduit to understand its activity. The TOUGH2-EOS2 model was used to reproduce the obtained temperature records and estimate geyser recharge/discharge parameters in both modes. Modeling shows that a larger cold inflow into the conduit causes a switch from cycling geyser to hot cycling spring mode. It was also found that the switch to cycling geyser mode corresponds to a larger mass of CO2 release during the time of the eruption.
Highlights
A thorough analysis of world-wide geyser distributions and functionality performed by Hurwitz and Manga [1] showed that geysers mostly occur within high-temperature hydrothermal systems hosted in active silicic volcanic areas
Thermodynamic calculations suggest that the dissolved CO2 and N2 modulate the dynamics of geysers and may trigger hydrothermal geyser eruptions when recharged into shallow reservoirs at high concentrations [2]
The Shaman geyser was formed in the Uzon caldera, Kamchatka in autumn 2008 in the place of a former hot spring
Summary
A thorough analysis of world-wide geyser distributions and functionality performed by Hurwitz and Manga [1] showed that geysers mostly occur within high-temperature hydrothermal systems hosted in active silicic volcanic areas. Analysis of some particular cases from the Valley of Geysers (Kamchatka) highlights the two factors: (i) the possibility of high porosity-permeability conduit formation due to fast rhyolite/thermal water chemical interaction in thermal spring discharge areas [6,7]; and (ii) the importance of CO2 -gas lift for driving geyser eruptions [8,9]. This paper examined a newly created geyser in Uzon (Appendix A, Figures A1–A8) as an example to address the above-mentioned issues. Another critical issue is whether a new Uzon geyser is a precursor of an on-going diatreme (Figure 2), which may eventually cause a catastrophic event in future. The modeling only focuses on the very last duration of the observations
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