GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 Three-dimensional magnetotelluric inversion applied in a sector of the Irpinia Fault System (Southern Apennine) M. Balasco 1 , M. De Girolamo 2 , D. Di Gennaro 3 , G. Romano 3 , A. Siniscalchi 3 1 Isttuto di Metodologie per l’Analisi Ambientale, CNR – Tito Scalo, PZ 2 Isttuto di Geofsica e Vulcanologia INGV, Roma 3 Università degli Studi di Bari The magnetotelluric (MT) method is a powerful tool to investgate seismotectonic regions thanks to its capability to image volumetric electrical conductvity variatons related to presence of interconnected fuids and partal melt (Bedrosian et al. 2014), especially if correlated with other geophysical observatons (Balasco et al. 2022). In this presentaton we show a preliminary 3-D electrical resistvity model obtained sector of the Irpinia Fault System (80x60km) acquiring n. 30 broad band magnetotelluric (MT) soundings at approximately intervals of 5 km, using the inversion code ModEM3DMT (Kelbert et al. 2014). The study area includes epicentral zones of the two greatest seismic events occurred in the last 100 years in the Southern Italy, 1930 and 1980 earthquakes. Mefte d'Ansanto, the largest source of natural CO2 gas emission measured on the Earth in a non‐volcanic environment, also falls in the investgated area (Chiodini et al. 2010). Many testng were performed building diferent startng models varying the dimension of horizontal and vertcal grid cells, model covariance, and inital damping factors to get the best resultant model for our data. The sea-efect was also taken into account because the coastline is very near to the investgated area. 3-D inversion approach has become fundamental for MT data interpretaton with respect to the 2- D inversion that frequently cannot explain important features from geologically complex regions. Unfortunately, the routne of 3-D codes require high-end workstaton or parallel machines, and long computatonal tme. Even if our preliminary MT model of the Irpinia sector is stll coarse, the results are promising also take into account a good agreement with other geophysical observatons. In partcular, the geostructural interpretaton of the 3D MT model will also beneft from the seismic data of the ISNET, INGV network and DETECT experiment (DEnse mulTi- paramEtriC observatons and 4D high resoluTion imaging, Picozzi et al. 2022).