The Marsili seamount is a 50-km-long volcanic ridge in the southern Tyrrhenian Sea within a back-arc basin about 75-85 km NW of the Aeolian arc volcanoes. Near-source tephra layers obtained from a core sample were determined by Iezzi et al. (2013) to be approximately 3,000 and 5,000 years old. Accretion of the ridge is thought to have begun around 1 Ma. Recent data also indicate that there is ongoing hydrothermal activity and shallow volcano-tectonic seismicity.