GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 Microseismicity and infrasonic monitoring at the Mefte d’Ansanto deep-CO 2 -rich gas emission site (Southern Apennines, Italy) L. Valoroso 1 , S. Cianet 2 , P. De Gori 1 , C. Giunchi 2 , L. Improta 1 , D. Piccinini 2 , L. Zuccarello 1 , F. Di Luccio 3 1 Isttuto Nazionale di Geofsica e Vulcanologia (INGV), Osservatorio Nazionale Terremot, Rome (Italy) 2 Isttuto Nazionale di Geofsica e Vulcanologia (INGV), Sezione di Pisa (Italy) 3 Isttuto Nazionale di Geofsica e Vulcanologia (INGV), Roma 1 (Italy) The role of fuids in the earthquake nucleaton process as well as in the evoluton of afershocks and swarms in space and tme is well-documented, yet it is stll an important issue for the seismological community to understand the physics governing the earthquakes. In partcular, numerous studies evidence the primary role that mantle-derived fuids play in the generaton of moderate to large upper crustal destructve earthquakes in extensional domains, where crustal- scale faults act as preferental hydraulic pathways. In this study, we focus on the Mefte d’Ansanto degassing site (Southern Apennines, Italy) which is the largest low-temperature non-volcanic CO 2 -rich gas emission site in the world, located at the northern tp of the Mw6.9 1980 Irpinia fault system. The study area experienced strong historical earthquakes (1702, 1732 and 1930 M6+ earthquakes) but it is characterised by a relatvely low background seismicity rate with respect to the nearby Sannio and Irpinia regions. To collect high-quality microseismicity data in this key sector of the southern Apennine extensional belt and investgate the relatonship among seismicity, crustal fuids, and physical-hydraulic propertes of the crust, we conducted a two years temporary experiment (June 2021 to May 2023) by installing a dense temporary network of 10 seismic statons equipped with short-period velocimeters (Lennartz 5sec). The temporary network covers an area of approximately 30x30 km 2 surrounding the Mefte d’Ansanto site and integrates with the numerous permanent statons of the INGV and ISNet permanent networks located at the boundary of the survey area. Within the Mefte area, we also deployed a temporary seismo-acoustc dense array to study two CO 2 degassing vents. We show frst results of the analysis of the seismicity recorded by the temporary network applying both standard (STA/LTA) detecton algorithms or innovatve enhanced techniques such as cross- correlaton based template-matching algorithms (Chamberlain et al., 2018) and/or Deep-Learning- Phase-Recogniton methods (Zhu and Beroza et al., 2018).