GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.2 GNGTS 2024 Magnetc Anomaly Survey of the Martgnano Lake maar center, Sabatni Volcanic District, Central Italy. I. Nicolosi 1 , F. D’Ajello Caracciolo 1 , G. Sotli 2 , N. Ricchet 3 , R. Carluccio 1 1 Isttuto Nazionale di Geofsica e Vulcanologia 2 Università di Roma, La Sapienza 3 Via Vallelunga 7, Rignano Flaminio (RM) ,Italy Introducton A magnetc anomaly survey was conducted at the Martgnano Lake volcanic center, which was formed during the fnal phases of the evolutonary history of the Sabatni Volcanic District (SVD) and persisted untl 70 ka when the last documented SVD erupton took place at the Martgnano maar (Marra et al., 2019). The SVD became actve 0.8 Ma and was characterized by explosive eruptons causing the depositon of pyroclastc fows and falls, surges and localized lava fows (Cioni et al., 1993). This volcanic actvity developed during Pleistocene tmes due to the post-orogenic extensional tectonics that led to the Tyrrhenian Sea opening (Malinverno & Ryan, 1986). The SVD extends over an area of 1800 km 2 and is characterized by the lack of a central volcanic edifce as the actvity was distributed over a large area. The SVD hydromagmatc centers mostly consist of tuf rings and subordinate tuf cones with maar-type craters located in the central area of the SVD, to the N and E of present-day Lake Bracciano (Sotli et al., 2012). The erupted tephra volumes from either monogenetc or polygenetc SVD maars ranged 0.004–0.07 km 3 during individual maar-forming eruptons. The structure of Martgnano lake was created by a sequence of hydromagmatc eruptons forming a composite maar type crater (Sotli et al. 2012). The maar structure is a common volcanic morphology that occurs when magma interacts with groundwater, leading to multple underground explosions and the formaton of a crater that cuts into the pre-eruptve surface. Maar volcanoes subsurface structure is a cone-shaped geometry (diatreme) generated by mass defciencies in the root zone, where the eruptve explosions occur; the diatreme and the maar crater are mainly due to explosions, collapse, and subsidence mechanism (Lorenz, 2003). Where no exposure of the diatreme exists, the applicaton of geophysical modeling techniques can provide a method to model the geometry of a maar-