ANNALS OF GEOPHYSICS, 59, 4, 2016, S0431; doi:10.4401/ag-7084 S0431 Acquisition procedures, processing methodologies and preliminary results of magnetic and ROV data collected during the TOMO-ETNA experiment Danilo Cavallaro 1,2,* , Luca Cocchi 3 , Mauro Coltelli 1 , Filippo Muccini 3 , Cosmo Carmisciano 3 , Marco Firetto Carlino 1 , Jesús M. Ibáñez 1,4 , Domenico Patanè 1 , Marco Filippone 5 , Erika Buttaro 6 1 Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania, Osservatorio Etneo, Catania, Italy 2 Università di Catania, Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Catania, Italy 3 Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma 2, Rome, Italy 4 Instituto Andaluz de Geofísica, Universidad de Granada, Granada, Spain 5 Università di Genova, Dipartimento di Informatica, Bioingegneria, Robotica e Ingegneria dei Sistemi, Genova, Italy 6 Nave Ammiraglio Magnaghi, Marina Militare Italiana ABSTRACT The TOMO-ETNA experiment was devised for the investigation of the continental and oceanic crust beneath Mt. Etna volcano and northeast- ern Sicily up to the Aeolian Islands, through an active source study. In this experiment, a large amount of geophysical data was collected both in- land and in the Ionian and Tyrrhenian Seas for identifying the major ge- ological and structural features offshore Mt. Etna and NE Sicily. One of the oceanographic cruises organized within the TOMO-ETNA experi- ment was carried out on the hydrographic vessel “Galatea” by Italian Navy. During the cruise a detailed magnetic survey and a set of ROV (re- motely operated vehicle) dives were performed offshore Mt. Etna. The magnetic survey allowed the compilation of a preliminary magnetic map revealing a clear direct relationship between volcanic structures and high frequency magnetic anomalies. Significant positive magnetic anomalies were identified offshore the Timpa area and along the easternmost portion of the Riposto Ridge and correlated to a primitive volcanic edifice and to shallow volcanic bodies, respectively. On the whole, the magnetic anomaly map highlights a clear SW-NE decreasing trend, where high amplitude positive magnetic anomaly pattern of the SW sector passes, northeastwardly, to a main negative one. ROV dives permitted to directly explore the shallowest sectors of the Riposto Ridge and to collect several videos and seafloor samples, allowing us to identify some locally devel- oped volcanic manifestations. 1. Introduction The TOMO-ETNA experiment (seismic TOMOg- raphy at Mt. ETNA volcano and surrounding areas) was carried out within the Task 5.3 “Mt. Etna struc- ture” of the European project “MED-SUV” (MEDiter- ranean SUpersite Volcanoes - Long-term monitoring experiment in geologically active regions of Europe prone to natural hazards: the Supersite concept), per- formed also with the resources of the European project “EUROFLEETS 2” [Ibáñez et al. 2016a, in this volume]. The main objective of the experiment was to gain a de- tailed geological and structural model of the continen- tal and oceanic crust beneath Mt. Etna volcano and northeastern Sicily up to the Aeolian Islands by per- forming a high-resolution seismic tomography through active and passive seismic methods accomplished both inland and offshore (either in the Ionian and Tyrrhen- ian Seas) [Coltelli et al. 2016, in this volume; Ibáñez et al. 2016a, in this volume]. A supplementary goal was the acquisition of geophysical data in the Ionian Sea to identify the main volcano-tectonic structures offshore Mt. Etna through multi-channel reflection seismic, magnetic, gravity and ROV (remotely operated vehi- cle) surveys. To achieve these objectives, during the sec- ond half of 2014, three specific oceanographic cruises were carried out [Coltelli et al. 2016, in this volume]. One of these cruises was performed between June 25 to July 3, 2014, on the catamaran hydrographic vessel (H/V) “Galatea” (Figure 1), provided by the Italian Navy within an agreement with the Istituto Nazionale di Geofisica Article history Received January 12, 2016; accepted May 6, 2016. Subject classification: Magnetic survey, ROV dives, Mt. Etna offshore, TOMO-ETNA experiment.