Evidences of directional soil response comportment

Abstract

In recent years, the importance of considering other peaks than the predominant in the soil response has been revendicated. One possible explanation for some of these secondary peaks in the soil response is the presence of strong lateral variations in the geology of the area. Specifically, the existence of paleochannels and streams in the city of Barcelona has been associated with the appearance of some of these double peaks. This work stems from the idea that it is reasonable that a linear structure such as a paleochannel or stream produces a directionality in the response of the site and therefore the directional peak does only affect the structures in this specific direction. On the other hand, the peak produced by the half-space outside the stream may also present a certain degree of directionality that influences the behavior of the structures. To study this possible phenomenon, we have chosen an area close to the border between Barcelona and L'Hospitalet de Llobregat, and, analyzed 11 ambient noise Horizontal to Vertical Spectral Ratio (HVSR) soil response measurements of 40 minutes length and applying circular statistics to the results. The results show clear indications of this directional behavior of the response peaks.