Interactions between volcanism and tctonics in the western Aeolian sector, southern Tyrrhenian Sea

Abstract

New high-resolution bathymetric and magnetic data from the western Aeolian sector, southern Tyrrhenian Sea, provide insights into structural and volcanic development of the area, suggesting a strong interaction between volcanism and tectonics. The analysis of these data combined with relocated earthquake distribution, focal plane solutions and strain rate evaluation indicates that the dextral strike-slip Sisifo-Alicudi shear zone is a complex and wide area of active deformation, representing the superficial expression of the deep seated lithospheric tear fault separating the subduction slab below Sicily and Calabria. Most of the observed volcanic features are aligned along a NW–SE trend, such as the Filicudi island-Alicudi North Seamount and Eolo-Enarete alignments, and are dissected by hundred-metre-high scarps along conjugate NNE–SSW trending fault systems. The magnetic field pattern matches the main trends of volcanic features. Spectral analysis and Euler deconvolution of magnetic anomalies show the existence of both deep and shallow sources. High-amplitude, high-frequency anomalies due to shallow sources are dominant close to the volcanic edifices of Alicudi and Filicudi, while the main contribution on the surrounding Eolo, Enarete, Alicudi North and Filicudi North seamounts is given by low-amplitude anomalies and/or deeper magnetic sources. This is probably related to different ages of the volcanic rocks, although hydrothermal processes may have played an important role in blanketing magnetic anomalies, in particular at Enarete and Eolo seamounts. Relative chronology of the eruptive centres and the inferred deformation pattern outline the Quaternary evolution of the western Aeolian Arc: Sisifo, Alicudi North and Filicudi North seamounts might have developed in an early stage, following the Late Pliocene–Early Pleistocene SE-ward migration of arc-related volcanism due to the Ionian subduction hinge retreat; Eolo, Enarete and Filicudi represent later manifestations that led volcanoes to develop duringMid-Late Pleistocene, when the stress regime in the area changed, due to the SSE-ward propagation of the subduction slab tear fault and the consequent reorientation and decrease of trench migration velocity. Finally, volcanic activity occurred in a very short time span at Alicudi, where an almost conical volcanic edifice emerged, suggesting negligible interactions with regional fault systems.