Crustal changes at Mt. Etna volcano accompanying the 2002-2003 eruption as inferred from a repeating earthquake analysis

In this work, waveform variations in repeating volcanotectonic earthquakes occurring from 2001-2009 in the northeastern flank of Mt. Etna were studied. Changes in waveform were found mainly during 2002-2003; and consisted of a decreasing similarity in the coda of events in earthquake families, as revealed by cross-correlation analysis, and delays, increasing proportionally to the lapse time, detected by coda wave interferometry. Such variations, mainly evident at stations located in the north-eastern flank of the volcano, were likely due to medium changes taking place within this region. Localized medium velocity decreases were inferred to occur in 2002-2003, followed by successive increases. The velocity decrease was interpreted as being caused by the opening or enlargement of cracks, produced by intruding magma bodies, intense ground deformation, and/ or VT earthquake activity that accompanied the 2002-2003 Mt. Etna eruption. On the other hand, subsequent velocity increases were interpreted as resulting from healing processes. © 2012. American Geophysical Union. All Rights Reserved.