GNGTS 2014 - Atti del 33° Convegno Nazionale

The HVB that controls the ascent of magma, has been interpreted by several authors as a high- density cumulate body crystallized at depth (Chiarabba et al. , 2004 and references therein). Although Mt. Etna is one of the best-studied volcanoes by using seismic tomography (e.g. Chiarabba et al. , 2004 and references therein; Patanè et al. , 2003, 2006) there are a number of shortcomings in the information which currently limit the reliably determination of the volcanic processes constraints, especially along the deepest paths of the magma rising. This inadequacy of the available passive tomography is based primarily on the fact that themajority of the earthquakes are shallow and clustered in small volumes, essentially within or close to the volcanic edifice down to 10 km depth. Thus, this earthquake distribution yields high-resolution tomographic images of the shallow crust and the upper portion of the volcano plumbing system. Therefore, due to the lack of recent active seismic surveys, a new active seismic experiment has been considered necessary to broaden the knowledge of the inner structure of Mt. Etna roots and the surrounding crust, spanning from the volcano basement down to the upper mantle. The results deriving from this experiment will constitute an important resource to better understand: i) the relationship between volcanism (i.e. Mt. Etna and Aeolian Islands) and plate tectonics, which still presents some shortcomings that the seismic experiment might clarify. In fact, Mt. Etna lies in the complex geodynamic setting of the south Tyrrhenian – Calabrian Arc – Ionian Basin, which originates from the diachronic and fragmented convergence between the Eurasia and Africa plates, one of the most intriguing tectonic areas worldwide, and ii) the magma ascent and eruptive dynamics of this volcano. Furthermore, integration between data acquired during the experiment with the earthquake dataset of the last 10 years, could provide an unique opportunity to calibrate passive seismic tomography obtained with new techniques in the context of the difficult task of interpretation of the volcano inner structure. With this vision in mind, we planned and carried out the TOMO-ETNA active seismic experiment during the summer of 2014. TOMO-ETNA, which is part of the European project “MEDiterranean SUpersiteVolcanoes (MED-SUV)”, has been coordinated by IstitutoNazionale di Geofisica e Vulcanologia together with the Granada University (Spain). TOMO-ETNA experiment integrates MED-SUV efforts with the resources of EUROFLEETS 2, another EC research project, and other funding agencies from Italy, Spain, and Germany. Furthermore, TOMO-ETNA has also been supported by the active participation of the Marina Militare Italiana and by the Dipartimento di Protezione Civile della Regione Siciliana. The focus of this experiment concerns the investigation of Etna’s roots and surrounding areas by means of passive and active refraction/reflection seismic methods. Therefore, this experiment included activities both on-land and offshore with the main objective to obtain a new high-resolution tomography in order to improve the 3D image of the crustal structures existing beneath the Etna volcano and the northeast Sicily (Peloritani - Nebrodi chain) up to Aeolian Islands. Its main objective is to achieve a structural model of the Earth crust in northeast Sicily, including an accurate mapping of tectonic structures (faults) and, consequentially, to define the physical processes controlling magma ascent beneath Mt. Etna. Overall, the information deriving from TOMO-ETNA could provide the answer to the many questions that have arisen while exploiting the large amount of data provided by the cutting-edge monitoring systems of Etna volcano and seismogenic aerea of eastern Sicily. The scheduled activities were divided into two actions: land and sea, and conducted from June 20 to July 25, although some of them will continue until November 2014. During the June - July period, a ����� �� ������ ��� ��� ����� ���� �������� �� ������������� ������ ��������� total of 13,292 air gun shots were produced by oceanographic vessel Sarmiento de Gamboa (��������� ������ ������ ���������� ������� ������� �������� �� ������� �������� CSIC-UTM, Spain; Fig.1) generating ������� ������� �������� �� ������� �������� seismic signals recorded by seismic stations deployed on-land and on the seafloor as well as the natural seismicity of the region. More of than 60 researchers participated to the experiment coming from different countries, mainly from Italy and Spain but also from Germany, Russia, U.S., Ireland and Mexico. Additionally, the Galatea vessel from the Istituto Idrografico della Marina Militare and Levanzo vessel always from the Marina �������� ���� ���� ���� �� ����� ��� ������� ����������� Militare have been used to carry out further geophysical GNGTS 2014 S essione 1.3 219