Estimation of Seismic Parameters Affecting the Ground Conditions in the City of Irkutsk

Analysis of violent earthquakes occurred in the past and detailed data on seismic regionalization and microregionalization were used to estimate quantitative parameters of seismic effects within the city of Irkutsk. The seismic effects were calculated in the form of accelerograms of a violent earthquake with the help of L. I. Ratnikova’s program aimed at selecting an accelerogram analogue on the basis of ground conditions and division of the site into two seismic zones which had background seismicities at 7 and 8 on the MSK-64 scale. Different empirical formulas based on global and regional data were used to calculate such earthquake parameters as relative durations, predominant periods, and maximum vibrational accelerations for the Irkutsk site.