Volcanoes: 15 are under the Tyrrhenian Sea, 7 previously unknown

Palermo - The South Tyrrhenian Sea is home to a range of 15 submarine volcanoes7 of which previously unknownarranged in a 90 km long, 20 km wide array that runs east to west. The news is the report of a number of oceanographic cruises conducted in recent years by an international team of volcanologists, geophysicists, and marine geologists of the National Institute for Geophysics and Volcanology, the Institute for Coastal Marine Environment of the National Research Council and New Zealands Institute of Geological and Nuclear Sciences.

The study 'Volcanism in slab tear faults is larger than that in island-arcs and back-arcs', published by Nature Communications, contributes to the knowledge of the Tyrrhenian Sea and opens new avenues to the interpretation of volcanic activities in subduction zones in the world (https://www.nature.com/articles/s41467-017-01626-w). "The South Tyrrhenian Sea is dotted with a number of volcanoes, some above sea level, i.e. the Aeolian Islands, others submerged, like Marsili", explains Guido Ventura, volcanologist and research team coordinator at INGV and IAMC. "This range of volcanoes, recently identified and described in the study, extends from approximately 90 km south of the Salerno coast to 30 km east of the Calabrian coast of Sangineto. The range, called Palinuro, extends in depth from about 3200 m to 80 m below sea level. Overall, these volcanoes represent a fault in the earths crust, through which magma from the Aeolian Islands, the central-southern Tyrrhenian Sea, and the area between Puglia and Calabria rises to the surface".

The data collected show that the whole volcanic range is larger than the Aeolian Islands and of the other submarine volcanoes in the southern Tyrrhenian Sea, including Marsili. "Additionally, many of these volcanic structures feature morphological characteristics similar to the opening of micro oceanic basins where new earth crust is formed as a result of magma rising up along fault lines," adds Salvatore Passaro, marine geologist at IAMC CNR. "These volcanoes were certainly active between 300,000 and 800,000 years ago, but they may also have been active more recently. Today they are responsible for submarine hydrothermal activity and are located within an abnormal thermal area (about 500 °C, 1 km under the seafloor)".

The oceanographic research cruises used an ROV (Remote Operating Vehicle) to acquire bathymetric, magnetic and gravimetric data, collect samples and conduct direct observations of the seafloor.