The Tyrrhenian Basin is the deepest part of the western Mediterranean: the Tyrrhenian Trench reaches a depth of 3800 meters. The origin of the Tyrrhenian is part of a broad geological process that has affected the entire Mediterranean area, linked to the convergence of the Eurasian and African tectonic plates. The process, which began 10 million years ago at the same time as the construction of the Apennine mountain ranges, is marked by volcanism.
Thus, its seafloor is characterized by the presence of numerous submarine ridges and volcanic type reliefs.
Many island or coastal volcanoes actually have extensive submarine parts. For example, 95 percent of the surface area of Stromboli volcano is below sea level. However, there are entirely submarine volcanoes that may be similar or larger in size than those on the surface.
Submarine volcanoes are very difficult to study because of the lack of direct access. Nonetheless, studies of marine geology in recent decades have allowed a greater understanding of their nature and operation. Observations and sampling are carried out by means of oceanographic ships.
In the case of the Italian seas, submarine volcanic activity is concentrated in parts of the Tyrrhenian Sea and the Sicilian Channel, where the Earth's crust is thinner and more fractured. Some submarine volcanoes are still active and sometimes manifest their presence by releasing gas and deforming very slowly; others now extinct represent real seamounts or seamounts. Their activity turns out to be different from that of volcanoes present on dry land because they are surrounded by seawater, which rapidly cools the emitted products and sometimes fragments the magma generating small explosions, the products of which are partly deposited on the bottom and dispersed by sea currents.
In addition to the best-known Marsili, Vavilov, and Magnaghi, the submarine volcanoes Palinuro, Glaucus, Aeolus, Sisyphus, and Enarete should be mentioned, as well as the numerous volcanic apparatuses in the Sicilian Channel, where the submarine eruptions off Pantelleria in 1891 and off Sciacca in 1831 represent the only historical records of this type of activity.
The International Commission. To acquire a more complete knowledge and assessment of the current state of activity of submarine volcanoes, provided for in Article 1 of opcm No. 3873 of April 28, 2010, the Head of the Department formalized the establishment of an international technical-scientific Commission, with the decree of April 18, 2011.
The Commission, composed of national and international experts, will serve for one year. The Commission's task will be to provide, in addition to periodic progress reports, a final report with an in-depth analysis based on the state of the art of the dangerousness of submarine volcanoes present in the Tyrrhenian Sea and the Strait of Sicily, as well as indications on how to direct studies and research and implement the monitoring system, for effective civil protection action.