Geophysical investigations supporting a 3D model reconstruction in the historical center of Rome: WP2-PREDICT Project

The historical center of Rome, due to the presence of a priceless cultural heritage, needs to be protected by natural risks including the seismic one. It is hence important to study the seismic response of downtown Rome in detail to estimate shaking levels in case of an earthquake. 

As widely known, to investigate the subsoil characteristics of a very highly urbanized area, geophysical techniques are the most effective, especially in the presence of ancient buildings which cannot be damaged by using invasive techniques. The new portable nodal seismic sensors, recently acquired by INGV, feature a compact, self-contained, autonomous land wireless seismic data acquisition system, making them well suited for use in urban environments.

In the framework of the PREDICT project (Progetto INGV Pianeta Dinamico St-Predict), WP2 aims to constrain the complex shallow geophysical subsoil model of a part of the urban centre of Rome as input for a reliable 3D model of the area to finalise the study of the seismic response in a range of frequencies of engineering interest.

Many geophysical campaigns were performed using the nodal sensors in sites selected based on the geological reconstruction of the area, in order to estimate the seismic characteristics of the subsoil for the different sites. Ambient noise measurements in a single station or array configuration were performed, together with downhole investigations.

In this work we show the results obtained in terms of microtremor spectral ratios curves (HVNSR) and velocity profiles correlated with the geological succession in order to identify possible lateral lithological variabilities which can significantly affect the expected seismic response.