ASSESSMENT OF SEISMIC CONDITIONS IN THE SHULBINSK HPP AREA

The Shulbinsk Hydroelectric Power Plant (HPP) is a critical infrastructure facility with a high level of engineering responsibility, necessitating a detailed assessment of local seismic hazard. This study presents the results of instrumental seismological investigations conducted within the Shulbinsk HPP area using data acquired from five temporary observation sites (SB1–SB5). Spectral characteristics of ambient seismic noise were analyzed, site response was evaluated using the Horizontal-to-Vertical Spectral Ratio (HVSR) method, and the obtained results were compared with amplitude ratios derived from recordings of earthquakes and quarry blasts.

The results indicate significant seismic heterogeneity across the study area. The most pronounced local amplification of seismic ground motion was identified at the embankment dam site (station SB1), where the increment in seismic intensity reaches approximately 0.7–0.9 points on the MSK-64 scale. In contrast, no significant increase in seismic intensity was observed at the remaining observation sites. The identified differences are associated with local soil conditions and low Vs30 values within the embankment body. Based on the consistency between the HVSR results and waveform analyses of recorded seismic events, recommendations are provided regarding the implementation of continuous seismic monitoring of the dam condition.

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