NAKAMURA METHOD, HVSR, H/V
Instrumentation for geognostic investigation
A significant part of the damages observed in destructive earthquakes all over the world is associated with the amplification of seismic waves due to the effects of the local site. The analysis of the site response is therefore essential in the evaluation of the seismic risk in areas subject to earthquakes. In order to evaluate the effects of the local site, a series of surveys must be carried out. Among the empiric methods, the method of spectrum analyses H/V on environmental vibrations is one of the most common. The method, also called “Nakamura” technique (Nakamura, 1989), was introduced by Nogoshi and Igarashi (1971) based on the initial studies of Kanai and Tanaka (1961). Since then, many researchers worldwide performed a large number of applications.
An important requirement to carry out the H/ V method consists in a fairly good knowledge of seismology combined with basic information on local geological conditions supported by geo-physical and geo-technical data. The method is generally applied in micro-zoning studies and in the analysis of the local response of specific sites.