Comparison of the Results and Applicability of Different Seismic Microzoning Methods for Territories in Platform Conditions with Weak Seismicity

Abstract

The article compares the results and estimation of the application conditions of seismic microzoning (SMZ) by numerical and instrumental methods for sites characterized by relatively small horizontal heterogeneity of the structure and properties of the soil strata. The results of applying the instrumental method for recording microseisms (Nakamura method) and calculation methods the of seismic stiffness and spectral transfer functions for SMZ of Oktyabrsky Island in Kaliningrad, Kaliningrad oblast were investigated. It is shown that the used SMZ methods yielded consistent results, differing mainly in the degree of detail and completeness of information. The results of the instrumental method for recording microseisms are characterized by the greatest detail and contain the most complete real, rather than model-calculated, frequency response of the expected seismic shaking. It is concluded that for weakly seismic areas with layered soil strata rather similar in structure to a horizontally homogeneous model, the choice of SMZ methods should be substantiated by the degree of importance of structures projected on the territory and, therefore, by the necessary amount of information on the frequency response of the expected vibrations and required site distribution details in seismic intensity increments.