Evidence of a dyke-sheet intrusion at Stromboli volcano inferred through continuous tilt

A tiltmeter, installed in the northern sector of the island of Stromboli (Aeolian archipelago, Tyrrhenian Sea), recorded a co-seismic offset at the time of the main shock (M-L 3.7) of the 7 November, 1994 swarm located 5 km north of the island. During the three months following this event a transient tilt anomaly, which was interpreted as due to a lateral intrusion and modelled through a dyke-sheet dislocation, was recorded. The tilt data were used in an analytical inversion based on a propagating tensile source with length and width increasing in time. The final result is consistent with the tectonic and structural framework of the volcano area.