GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 Ofshore fault geometry revealed from earthquake locatons using new state-of-art techniques: the case of the 2022 Adriatc Sea earthquake sequence Like An* 1 , Francesco Grigoli 2 , Bogdan Enescu 1,3 , Mauro Butnelli 4 , Mario Anselmi 4 , Irene Molinari 4 , and Yoshihiro Ito 5 1 Department of Geophysics, Graduate School of Science, Kyoto University, Kyoto, Japan 2 Department of Earth Sciences, University of Pisa, Pisa, Italy 3 Natonal Insttute for Earth Physics, Magurele, Bucharest, Romania 4 Natonal Insttute of Geophysics and Volcanology, Italy 5 Disaster Preventon Research Insttute, Kyoto University, Uji, Kyoto, Japan On November 9, 2022, 6:07 AM (UTC), a sequence of two M>5 earthquakes (mainshock of Mw 5.5) occurred 30 km NE of the coast of Fano, Italy. Since locatng ofshore earthquakes is challenging, we have applied a combined approach to constrain the geometry and depth of the sequence events beter. Six M3+ events were frst relocated using a travel tme stacking method. Next, using the six M3+ earthquakes as reference events, we applied a diferental travel-tme method to reconstruct the earthquake cluster geometry and locate the remaining events, including the mainshock. The results reveal a 25-35 degree SW dipping cluster. The depth of the mainshock hypocenter obtained using this procedure agrees well with that determined by depth phases. This study's relatvely sharp earthquake cluster geometry is consistent with the thrust faults revealed by a local seismic refecton survey and focal mechanism solutons. These approaches are partcularly useful for ofshore monitoring of industrial operatons (e.g., Carbon Dioxide and Methane storage). Corresponding author: Like An ( like.an.65h@st.kyoto-u.ac.jp) , Mauro Butnelli ( mauro.butnelli@ingv.it)