Microseismicity spectral features analysis of the Mutnovsky volcano fumarole fields area

Time-frequency analysis of 40-hour seismic records of the temporary seismological network, performed using a systematic visual inspection of seismograms, spectrograms, and signal spectra in small time windows (from 30 s to 10 min), made it possible to identify several manifestations of volcanic seismicity in the Mutnovsky fumarole field area, as well as some non-volcanic signals. The former includes signals interpreted as a volcano-tectonic earthquake (only a single event was found), multiple swarms of hybrid and long-period earthquakes, as well as a stable (constant for 40 hours) microseismic signal likely related to the gas-hydrothermal activity of fumarole fields in the northeastern crater of the volcano. For specific stations of the network, the differences between simultaneously recorded signals were considered, an assessment was made of the influence of natural factors characteristic of the study area: hydrogeological and meteorological.