The result of ambient noise tomography for the Kambalny Volcano (South Kamchatka), where the first time in the entire history of observations a violent phreatic eruption was observed in March-April 2017, is presented. The results obtained clarify the structure of the upper part of the edifice of the Kambalny Volcano and are consistent with independent data on body waves, as well as with geological information. According to seismotomographic data of the surface waves, low-velocity anomalies are distinguished in the model of the structure of the volcanic edifice. They are asymmetric relative to the volcano cone and are allocated to loose pyroclastic deposits of past eruptions and to deep sources of hydrothermal activity. Perhaps the migration of fluids in these hydrothermal vents to the north and west of the volcano and their interaction with the magma chamber in the upper crust caused the explosive eruption.
