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This work sets out to identify a state-of-the-art system to be used for the calibration of seismic sensors. The aim is to acquire such a system within the framework of the PON ARS01 00926 EWAS (an Early Warning System for cultural heritage) project, which seeks to develop new technologies for the protection, conservation and safety of cultural heritage and envisages creating a newly developed seismic monitoring system. This system will exploit the ETL3D/5s-H hybrid sensors, resulting from the integration of a precision accelerometer within the ETL3D/5s velocimeter [Fertitta et al., 2020]. The new calibration system, already acquired and being installed, can be used by the EWAS project partners (including the National Institute of Geophysics and Volcanology and the Kore University of Enna), to calibrate the ETL3D/5s-H sensors, and by external organisations to calibrate or gauge other seismic sensors, thus providing a useful service to the scientific community and supporting industrial activities. This paper presents the method used and the activities undertaken to define the technical specifications of the calibration system. A feasibility study of an electromechanical vibrating table and the testing of two electrodynamic calibration systems were carried out. One of the electrodynamic systems is the CS18P (Calibration System for Seismic Sensors) produced by the German firm SPEKTRA. The CS18P comprises two vibrating tables, one horizontal and one vertical, which, thanks to their fluid-dynamic suspension, eliminate the sliding and rolling friction associated with the movement of the moving part with respect to the fixed part. A hardware and software system monitors and controls the motion in real time, analyses the data and automatically processes a predefined set of measurements. In the light of the technical specifications and experimental results, the CS18P represents the ideal solution for the aims of the EWAS project and also in view of the possible future uses of the calibration system., Questo lavoro si propone di identificare un sistema allo stato dell’arte da utilizzare per la calibrazione di sensori sismici. L’obiettivo quello di acquisire un siffatto sistema nell’ambito del PON ARS01 00926 EWAS (an Early Warning System for cultural heritage), che mira a sviluppare nuove tecnologie per la tutela, la conservazione e la sicurezza del patrimonio culturale e prevede la creazione di un sistema di monitoraggio sismico di nuova concezione. Questo sistema sfrutter i sensori ibridi ETL3D/5sH, derivanti dall’integrazione di un accelerometro di precisione all’interno del velocimetro ETL3D/5s [Fertitta et al., 2020]. Il nuovo sistema di calibrazione, gi acquisito e in corso di installazione, potr essere utilizzato dai partner del progetto EWAS (tra cui l’Istituto Nazionale di Geofisica e Vulcanologia e l’Universit Kore di Enna), per calibrare i sensori ETL3D/5sH, e da Enti esterni per calibrare o tarare altri sensori sismici, fornendo cos un servizio utile alla comunit scientifica e di supporto alle attivit industriali. Questo lavoro presenta il metodo seguito e le attivit svolte per la definizione delle specifiche tecniche del sistema da acquisire. Si quindi proceduto ad uno studio di fattibilit di una tavola vibrante elettromeccanica e alla verifica di due sistemi di calibrazione elettrodinamici. Uno dei sistemi elettrodinamici il CS18P (Calibration System for Seismic Sensor) prodotto dalla compagnia tedesca SPEKTRA. Il CS18P comprende due tavole vibranti, una orizzontale e una verticale, che grazie alla sospensione fluidodinamica eliminano gli attriti radenti e volventi associati al movimento della parte mobile rispetto a quella fissa. Un sistema hardware e software monitora e controlla il moto in tempo reale, analizza i dati e processa automaticamente un insieme prestabilito di misure. Alla luce delle specifiche tecniche e dei risultati sperimentali, il CS18P rappresenta la soluzione ideale in relazione agli scopi del progetto EWAS anche in considerazione dei possibili impieghi futuri del sistema di calibrazione.

Results of passive seismic surveys, in terms of both amplification and polarization effects in a section of the Tremestieri Etneo Fault (Sicily Eastern center - Catania) are discussed. For the purpose, velocimetric and accelerometric records of seismic ambient noise were analyzed. The polarization analysis of particle motion was performed and azimuthally dependent resonant frequencies were estimated. Ambient noise data were also used to assess the dynamic properties of a reinforced concrete building, located on the fault zone. The fundamental modes have been estimated through ambient noise recordings acquired by three-directional accelerometers, installed at the highest accessible floor and outside the building. The study revealed a clear oriented seismic amplification in the fault zone. This effect was observed in intensely jointed rock masses, located inside the fault area, as the result of specific geometries and significant directional impedance contrasts characterizing the area under study. The analyses show that the direction of the largest resonance motions has transversal relationship with the dominant fracture orientation. The directional amplification is inferred to be produced by stiffness anisotropy of the fault damage zone, with larger seismic motions high angle to the fractures. The results obtained are in complete agreement with those obtained by a previous study which analyzed the fault section located to the north-west.Finally, comparing the dynamic properties of the school building and the vibrational characteristics of the soil in the direction of maximum amplification, no clear resonant effect in the soil-structure interaction has been observed., This paper has been funded by the following research projects: “Attività di sviluppo sperimentale finalizzata alla riduzione del rischio sismico nella Sicilia Orientale” inside the PO-FESR 2007-2013 Sicilia; MED-SUV funded from the European Union Seventh Framework Programme (FP7) under Grant agreement n°308665. This work is sponsored by European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement n° 798480.