Evaluation of building fundamental periods and effects of local geology on ground motion parameters in the Siracusa area, Italy

Abstract

The Siracusa area, located in the southeastern coast of Sicily (Italy), is mainly characterized by the outcropping of a limestone formation. This lithotype, which is overlain by soft sediments such as sandy clays and detritus, can be considered as the local bedrock. Records of ambient noise, processed through spectral ratio techniques, were used to assess the dynamic properties of a sample survey of both reinforced concrete and masonry buildings. The results show that experimental periods of existing buildings are always lower than those proposed by the European seismic code. This disagreement could be related to the role played by stiff masonry infills, as well as the influence of adjacent buildings, especially in downtown Siracusa. Numerical modeling was also used to study the effect of local geology on the seismic site response of the Siracusa area. Seismic urban scenarios were simulated considering a moderate magnitude earthquake (December 13th, 1990) to assess the shaking level of the different outcropping formations. Spectral acceleration at different periods, peak ground acceleration, and velocity were obtained through a stochastic approach adopting an extended source model code. Seismic ground motion scenario highlighted that amplification mainly occurs in the sedimentary deposits that are widespread to the south of the study area as well as on some spot areas where coarse detritus and sandy clay outcrop. On the other hand, the level of shaking appears moderate in all zones with outcropping limestone and volcanics.

Shear‐wave velocity structure from MASW and SPAC methods: The case of Adra town, SE Spain

“…Some of them were severely damaged during the Adra 1993‐1994 earthquake sequence (Figure ). The analysis of microtremor measurements is a quick, easy and inexpensive way to assess the dynamic behaviour of building structures based on the fact that microtremor spreads on the building structure and is amplified at soil predominant periods close to the natural period of the building (Panzera et al ). Other important features are the main building‐damage distribution zone located in the transition among the G2, classified as EC8 Class B1‐type, and the Holocene Adra river alluvial fan and colluvials fans, classified as EC8 Class C‐type (180–360 m/s).…”

“…With V s above 1000 m/s, the Palaeozoic schist hard rock appears shallower on the right-hand side of profile. The presence of shallowest Palaeozoic schist, displaying better subsurface mechanical properties in terms of seismic amplification, justifies why no building building structure and is amplified at soil predominant periods close to the natural period of the building (Panzera et al 2016).…”

GPR Clutter Amplitude Processing to Detect Shallow Geological Targets

“…In addition, the survey was also compared to passive seismic measurements and borehole data is specific zones of the profiles. Horizontal to Vertical Spectral Ratio (HVSR) is a passive seismic methodology, applied in many cases to determine the thickness of ground materials (e.g., [33,34]) and to map site effects (e.g., [23,[35][36][37]). A wide description of the methodology and the application can be found in [30,38].…”

Structural health monitoring and Earthquake Early Warning: preliminary studies for application in eastern Sicily

“…A similar mismatch was observed between several curves obtained by experimental measurements [e.g., Navarro et al, 2007;Gallipoli et al, 2009;Masi and Vona, 2009], and the the EC8 theoretical law. Panzera et al [2016] suggest that this disagreement may be due to the use of a low energy input source such as the one by the ambient noise. However, different types of seismic source have been taken into account in this study, always obtaining the same values of the fundamental period.…”