Regional Mapping of the Average Shear Wave Velocity for Geotechnical Applications - An Example in North-eastern Italy

Abstract

We utilised the Refraction Microtremors (ReMi) seismic technique to conduct a regional survey targeting the average shear wave velocity in the uppermost 30 m in the Province of Treviso in north-eastern Italy. The ReMi technique was chosen because of its cost effectiveness as the field operations can be easily conducted by single person The data acquisition grid was optimised using a multidisciplinary approach. Each VS recording station was precisely located based on a high-resolution depositional model of the entire venetian plain. A total of 250 recording stations, scattered over an area of 2000 square km, were collected in a time window of a month in the early 2006. Data processing faced some problems as in some cases spectral quality was not satisfying and the dispersion curve could not be identified with an adequate degree of confidence. A percentage of 10% of the collected were discarded. The final VS map showed a surprisingly correlation with the alluvial and fluvio-glacial depositional model acting during late Pleistocene and Holocene. The ReMi technique and more generally the surface wave based techniques proved to be a valuable tool for the regional mapping of average values of VS in the near surface strata.