Study of the Relationship between Peak Ground Accelerations in Fault Zones of Strong Earthquakes and Magnitude and Distance from the Source Based on a Large Dataset (Verification of Regulatory Formulas SP 286.1325800.2016 “Critical Infrastructure: Rules for Detailed Seismic Zoning”)

Abstract

To verify the regulatory formulas SP 286.1325800.2016, records obtained by stations of the K-NET and KiK-net strong motion networks in Japan were studied. The peak ground accelerations recorded during strong earthquakes in three magnitude ranges—6.6–6.7, 6.8–7.0, and 7.1–7.3—and calculated using the SP formulas were compared. A large scatter of experimental acceleration values for fixed magnitudes and distances from the source was obtained, associated with the dependence of peak ground accelerations on the characteristics of the source and wave propagation medium (orientation of the fault plane and distribution of displacements on it, released stress, source spectrum, frequency-dependent quality factor of the medium, local frequency-dependent amplification, soil response, surface topography and internal boundaries, etc.). Calculations using the SP regulatory formulas are based on clouds of experimental data, but significantly underestimate peak ground accelerations, especially in the focal and near zones. The SP regulatory formulas provide only approximate estimates that can be used as a reference, but in practice, for critical infrastructure, more reliable methods for assessing peak ground accelerations and other parameters of seismic impacts should be used, taking into account regional characteristics and recurrence periods of earthquakes, with elements of probabilistic analysis.