GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.2 GNGTS 2024 diatreme, its feeder dikes, and any intrusions (Skacelova, 2010, Blaikie et al., 2014, Mrlina, 2009 ). Potental feld methods have proven valuable in providing informaton about volcanic structures and subvolcanic bodies, presentng a valid approach to probe through a volcanic pile (Nicolosi et al., 2014, 2016). Short wavelength magnetc anomalies have been observed inside maars craters, ofen associated with high gravimetric signature and interpreted as dikes that intruded the diatreme in the center of the main crater (Blaikie et al., 2014). The Martgnano lake survey The magnetc survey of Martgnano center represents a novelty, as this type of data has never been acquired for this volcanic center before. The survey was conducted using an infatable boat designed for lake navigaton and equipped with a GEM Systems GSM 19 magnetometer to measure the total magnetc intensity. Additonally, a GPS system for obtaining spatal coordinates of the magnetc measurements is integrated into the magnetometer platorm. The entre surface of the lake, which measures approximately 1890x1400m, was surveyed using profle lines oriented in the N-S directon and spaced 50 meters apart (Fig. 1). A series of Tie-lines E-W oriented were acquired to correctly level the main survey lines. While navigatng the lake, echosounder measurements were conducted using a Garmin Striker V7 unit equipped with a transducer operatng at 200 kHz. These measurements were gathered to construct a model of the lake's bathymetry and to examine morphological structures originatng from volcanic actvity. Throughout the measurements, numerous gas bubble emissions in the form of fares (contnuous release of gas bubbles,) were observed. These emissions, characterized by high sonic impedance of the bubbles, scater the echosounder signal, making them distnctly visible ( Caudron et al. 2012). They were partcularly concentrated in an area labeled FL in Fig. 3. Exploraton of the lake botom focusing on the region of higher density of observed fares was conducted using a submarine ROV (Remotely Operated Vehicle) equipped with a camera and a robotc arm. Two aeromagnetc profles, obtained during a previous survey covering the entre SVD, are situated to the west and east of the lake border in a north-south directon (referred to as L1 and L2, as shown in Fig. 2). The average alttude maintained during the aeromagnetc survey was 400 meters above ground level.