Microgravity observations at Mt. Etna have been routinely performed as both discrete (since 1986) and continuous (since 1998)
measurements. In addition to describing the methodology for acquiring and reducing gravity data from Mt. Etna, this paper
provides a collection of case studies aimed at demonstrating the potential of microgravity to investigate the plumbing system
of an active volcano and detect forerunners to paroxysmal volcanic events. For discrete gravity measurements, results from
1994–1996 and 2001 are reported. During the first period, the observed gravity changes are interpreted within the framework
of the Strombolian activity which occurred from the summit craters. Gravity changes observed during the first nine months
of 2001 are directly related to subsurface mass redistributions which preceded, accompanied and followed the July-August 2001
flank eruption of Mt. Etna. Two continuous gravity records are discussed: a 16-month (October 1998 to February 2000) sequence
and a 48-hour (26–28 October, 2002) sequence, both from a station within a few kilometers of the volcano's summit. The 16-month
record may be the longest continuous gravity sequence ever acquired at a station very close to the summit zone of an active
volcano. By cross analyzing it with contemporaneous discrete observations along a summit profile of stations, both the geometry
of a buried source and its time evolution can be investigated. The shorter continuous sequence encompasses the onset of an
eruption from a location only 1.5 km from the gravity station. This gravity record is useful for establishing constraints
on the characteristics of the intrusive mechanism leading to the eruption. In particular, the observed gravity anomaly indicates
that the magma intrusion occurred “passively” within a fracture system opened by external forces.
Keywords Mt. Etna - Microgravity - magma sources - modeling