Applicability of the H/V Method in the Seismic Microzoning Problem

Abstract

The paper discusses the applicability of the horizontal-to-vertical spectral ratio for ground motion (H/V method) to estimate the seismic intensity increment and trace the bedrock surface covered by soil layers. The first issue is the classic seismic microzoning problem; the second is related to structural mapping of the upper part of the geological profile. The authors assess the possibility of using a single station to estimate the intensity increment without synchronization of data at a given point at a site with records based on reference rocks. It is shown that such an approach is invalid, because the maximum variations in the H/V ratio during a day may reach 2.7 times; a degree of intensity of 0.8 will correspond to such variation. At the same time, it is shown that the resonance frequencies of soil layers are stable. If the mean velocities of seismic waves are known at some points of profile surface, the position of the underlying bedrock top can be traced with confidence.