Electrotomography Studies in the Uzon Caldera at Shaman Geyser (Kamchatka Peninsula)

Abstract

In 2020, in the caldera of Uzon volcano (Kamchatka Peninsula), electrical prospecting studies were carried out using the electrotomography method within the eastern thermal field near Shaman geyser. The geoelectric section is divided into three zones according to the level of electrical resistivity: relatively high-resistivity cold zones at the edges and a relatively low-resistivity hot zone in the center. The hot zone, situated at a depth of 5–20 m and hosting the Shaman geyser, is distinguished by anomalously low resistivity (less than 0.5 Ω m), which indicates the highest fracturing and saturation of rocks with fluid. Resistivity monitoring was carried out above the geyser using an Omega-48 electrical tomography station and two cables with lengths of 235 and 47 m. The first cable provided a survey depth of 60 m; the second, ∼12 m. Four phases of the geyser’s operation are distinguished on the difference geoelectric sections, constructed from the monitoring results: filling, outpouring, spouting, and steaming in the form of alternating positive and negative electric field anomalies. The channel to the geyser was found from the results of areal measurements.