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Featured Application: The use of non-destructive diagnostic techniques for the in situ and non-invasive mechanical characterization of historic stone masonry. The design of strengthening and securing work for historic buildings requires knowledge of the masonry mechanical characteristics, often obtainable through laboratory tests that require invasive samples. The non-destructive techniques, applicable in situ in a rapid and non-invasive way, represent a valid alternative to estimate mechanical strengths without destructive sampling. In this study, a methodology was calibrated which, by combining the results of the ultrasonic and impact tests, makes it possible to reach a good estimate of the compression strength and elastic modulus of a particular rock: sandstone. Most buildings in Amatrice, the city devastated by the violent earthquake of Central Italy in 2016, were built by means of this sedimentary rock. By carrying out a diagnostic campaign on the remaining walls of the St. Agostino church in Amatrice, it was possible to obtain a correlation, specific for this case study, between the compression strengths from laboratory tests and the results of the ultrasonic and impact tests. Unlike the traditional Sonreb methods, this methodology wanted to favor the use of the impact method instead of the sclerometrer test. In this way, it will be possible to operate on other damaged buildings of similar construction types located in the seismic crater of Amatrice, evaluating the mechanical characteristics of the masonry structures be means of in situ non-destructive tests in order to design the safety and strengthening work. [ABSTRACT FROM AUTHOR]

On 24 August 2016, the M 6.2 Amatrice earthquake struck central Italy, well-known as a seismically active region, causing considerable damage to buildings in the town of Amatrice and the surrounding area. Damage from this earthquake was assessed quantitatively by means of multitemporal synthetic aperture radar (SAR) coherence and SAR intensity methods using dual-polarized SAR data obtained from the Sentinel-1 (VV, VH) and ALOS-2 (HH, HV) satellites. We developed linear discriminant functions based on three items: (1) the differential coherence values; (2) the differential backscattering intensity values of pre- and post-event images; and (3) a binary damage map of the optical pre- and post-event imagery. The accuracy of the proposed model was 84% for the Sentinel-1 data and 76% for the ALOS-2 data. The damage proxy maps deduced from the linear discriminant functions can be useful in the parcel-by-parcel assessment of building damage and development of spatial models for the allocation of urban search and rescue operations. [ABSTRACT FROM AUTHOR]

On 24 August 2016, a Mw 6.0 earthquake started a damaging seismic sequence in central Italy. The historical center of Amatrice village reached the XI degree (MCS scale) but the high vulnerability alone could not explain the heavy damage. Unfortunately, at the time of the earthquake only AMT station, 200 m away from the downtown, recorded the mainshock, whereas tens of temporary stations were installed afterwards. We propose a method to simulate the ground motion affecting Amatrice, using the FFT amplitude recorded at AMT, which has been modified by the standard spectral ratio (SSR) computed at 14 seismic stations in downtown. We tested the procedure by comparing simulations and recordings of two later mainshocks (Mw 5.9 and Mw 6.5), underlining advantages and limits of the technique. The strong motion variability of simulations was related to the proximity of the seismic source, accounted for by the ground motion at AMT, and to the peculiar site effects, described by the transfer function at the sites. The largest amplification characterized the stations close to the NE hill edge and produced simulated values of intensity measures clearly above one standard deviation of the GMM expected for Italy, up to 1.6 g for PGA. [ABSTRACT FROM AUTHOR]