GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 2.2 GNGTS 2023 EMERSITO decided to focus the scientific intervention in the municipal area of Ancona which is the main city of the Marche region. This choice was driven by: a) the values of peak ground accelerations observed during the main shock in the city compared with other cities at the same or lower epicentral distance (Ancona: 198 cm/s2 at about 50 km, Cattolica: 32 cm/s2 at about 47 km); b) the observed damage, fortunately minor, and evacuations reported by the technicians of Regione Marche and the Fire Brigade; c) the scientific interest in the evaluation of the local seismic response in the urban area that is characterized by strong lithological heterogeneities; d) the presence of an INGV office in Ancona which supported the activities of all the INGV emergency groups, including the EMERSITO working group. EMERSITO group communicates the progress of its activities through the publication of reports (EMERSITO Rapporto n.1, EMERSITO Rapporto n.2, EMERSITO Rapporto n.3) available online. The intervention of EMERSITO concerned the installation of a temporary seismic network (registered as 6N; the code was released by FDSN, the Federation of Digital Seismograph Networks) consisting of 11 seismic stations equipped with both velocimetric and accelerometric sensors. A part of these stations (6) has been set up in real-time mode, i.e. through a modem the seismic data are transmitted to a dedicated server and the stations can be configured and interrogated remotely to verify their operation status. The remaining stations (5), on the other hand, have a local acquisition system, i.e. data are stored on a removable memory medium, and therefore require periodic maintenance interventions for checking and downloading the data. At the end of the experiment, all continuous data will be transferred to the European Integrated Data Archive (EIDA) repository, with a Digital Object Identifier (DOI) after their organization and the quality check. They will be made public after a pre-established restriction period to allow preliminary data analysis and a general publication about the intervention of the EMERSITO group. Site selection for network 6N was planned on the basis of the geological map, damage survey and other information. It was preceded by field inspections in collaboration with the technicians of the Municipality of Ancona and Regione Marche and was supported by colleagues from the INGV headquarter in Ancona. Given the observed variability in the seismic response of the permanent stations, particular attention was paid to the identification of one or more reliable reference sites, also through expeditious ambient noise measurements. The location of the 6N stations is indicated in Fig. 1. The deployment of the network took place between 13 and 17 November: the 11 stations were installed on the ground floors, basements or courtyards of public or military buildings (schools, universities, sports centers, the Palace of the Regione Marche, religious structures, the headquarters of the Navy, the Lighthouse in the Cardeto Park) and private individuals. In this work we present the seismic dataset composed of ambient vibrations and aftershock recordings acquired from the 6N network during the experiment. Preliminary data analysis suggests a variability of the site responses depending on the outcropping lithologies (Fig. 2). We