Structural features of Panarea volcano in the frame of the Aeolian Arc (Italy): Implications for the 2002–2003 unrest

Panarea, characterized by gas unrest in 2002–2003, is the volcanic island with the least constrained
structure in the eastern-central Aeolian Arc (Italy). Based on structural measurements, we define here its
deformation pattern relative to the Arc. The main deformations are subvertical extension fractures (63%
of data), normal faults (25%) and dikes (12%). The mean orientation of the extension fractures and faults
is ∼N38◦E, with a mean opening direction of N135◦ ±8◦, implying extension with a moderate component
of dextral shear. These data, matched with those available for Stromboli volcano (pure opening) and
Vulcano, Lipari and Salina volcanoes (predominant dextralmotions) along the eastern-central Arc, suggest
a progressivewestward rotation of the extension direction and an increase in the dextral shear. The dextral
shear turns into compression in the western arc. The recent unrest at Panarea, coeval to that of nearby
Stromboli, may also be explained by the structural context, as both volcanoes lie along the portion of the
Arc subject to extension.

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