The activities of the EMERSITO INGV emergency task force following the Mw 5.5 Costa Marchigiana-Pesarese earthquake

EMERSITO is the INGV emergency task force (website available at http://emersitoweb.rm.ingv.it/) with skills and experience in seismic response studies and in seismic microzonation activities, and contributes to emergency interventions following significant seismic events (M>5.0 or lower if a noticeable level of damage is observed).

After the Mw 5.5 (M_L 5.7) event of November 9, 2022 06:07:24 UTC (Italian time 07:07:24) localized in the Costa Marchigiana Pesarese area, EMERSITO acted immediately to collect multidisciplinary available information regarding the epicentral area and adjacent areas.

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; 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. 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, while the remaining stations (5), have a local acquisition system, requiring periodic maintenance interventions for checking and downloading the data.

At the end of the experiment, after a quality check all continuous data will be transferred to the European Integrated Data Archive (EIDA) repository, with a Digital Object Identifier (DOI) and made public after a pre-established restriction period to allow both 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. The deployment of the network took place between 13 and 17 November.

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. We believe that the instrumental data acquired by EMERSITO task force, together with the microzonation study available for the municipality of Ancona can increase the knowledge on possible site effects that occurred in different areas of the city after the Mw 5.5 event of November 9, 2022.