Earthquake source zone model and prediction of strong ground motion parameters

Abstract

Relevance. Prediction of quantitative parameters of seismic ground motion, based on studies of strong ground motion records, is the final part of the set of works on the seismic hazard assessment of any territory. At the same time, the results of studying the processes of seismic wave’s generation and propagation in the near zones of earthquakes are of great importance for the physics of the earthquake source, being the basis for constructing an adequate model of the source and the processes occurring in it. The regularities of propagation of a seismic wave field are expressed in the equations of connection between the parameters of seismic vibrations and the characteristics of the source and the medium. These equations can be obtained both from the theoretical positions available in today’s seismological science, and from the analysis of accumulated data on strong ground motion records. It does not require proof that the interpenetration of these two methods is the most fruitful for the development of scientific progress. The trend of recent decades in the development of equations for predicting the parameters of strong ground motions is the identification of several zones in the wave field with different dependences on the parameters of the medium and source. The predictive ratios obtained using this method are distinguished by a decrease in the scatter of estimates of the fluctuation parameters and compliance with empirical data. When processing statistical data using the theory of dimension and similarity, it was found that in the field of seismic waves there are similar distances at which the values of the vibration parameters are similar. In other words, there are laws for scaling the parameters of seismic ground motion. A similar statement can be found in theoretical works devoted to the generation of seismic waves by an earthquake source. The aim of the work is – using theoretical provisions on processes in the source area, to establish the laws of generation and propagation of parameters of strong ground movements, taking into account empirical data, to develop a model of the source area that does not contradict empirical data, to determine the size of the earthquake source area. Research methods – statistical analysis of empirical data on strong ground motion. Results of the work – attenuation equations for the amplitudes of peak ground accelerations in the fault, near- and far-field zones are proposed; predictive equations for the prevailing periods and duration of vibration of strong ground motion; the sizes of the source area of the earthquake were estimated.