Experimental Evaluation of the Dynamical Parameters f0 and A0 Using the Method HVSR

Microzonation is one of the main tasks in the analysis of the seismic hazard, seismic risk and the following political planning to lower damage from earthquakes. For the purposes of microzonation first the dynamical capabilities of the soil have to be determined. This information can be attained by invasive and time-consuming methods. Extra problems arise in a city area where the measurements are affected by industrial noise and traffic. It is necessary the development of quick, effective and non-invasive methods aimed at the evaluation of the seismic characteristic of the upper layers of Earth`s crust. Passive seismic methods depend on the registration and analysis of microseismic noise from a natural, as well as from anthropogenic origin, the latter being very common in cities.

In this research for the purpose of evaluating the resonance effects by seismic waves is used the method of Horizontal to Vertical Spectral Ratio (HVSR) of microseismic noise, which can evaluate the relation between soil/construction. For areas with potentially high seismic risk, like the one that is observed in the area of Sofia, this method is suitable. This method is suitable for a city area because it does not need sources of artificial origin.