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GEOPHYSICAL RESEARCH LETTERS, VOL. 30, NO. 20, 2077, doi:10.1029/2003GL018250, 2003

Intrusive mechanism of the 2002 NE-Rift eruption at Mt. Etna (Italy) inferred through continuous microgravity data and volcanological evidences

Stefano Branca

Università di Catania-Dipartimento di Scienze Geologiche, Catania, Italy


Daniele Carbone

Istituto Nazionale di Geofisica e Vulcanologia-Sezione di Catania, Catania, Italy


Filippo Greco

Istituto Nazionale di Geofisica e Vulcanologia-Sezione di Catania, Catania, Italy


Abstract

In October 2002 a new eruption began at Etna. Lava flows were issued from two different fissure systems on the NE and S flanks of the volcano. A continuous microgravity sequence, acquired at a station on the N slope (2800 m a.s.l.), shows a marked decrease (about 400 μGal in less than one hour) about 4 hours before lava was first emitted from the eruptive fissures along the NE-Rift. This anomaly reversed soon afterward at a high rate. The strong gravity decrease is interpreted as the opening, by external forces, of a shallow fracture system 1 km W of the gravity station. Magma from the central conduit entered the new fracture system passively, and propagated through it towards lower portions of the NE-Rift. Both the arrangement of the new fracture system and the eruptive dynamics are in keeping with the inferred intrusive mechanism.

Received 25 July 2003; accepted 30 September 2003; published 31 October 2003.

Index Terms: 1294 Geodesy and Gravity: Instruments and techniques; 8122 Tectonophysics: Dynamics, gravity and tectonics; 8414 Volcanology: Eruption mechanisms; 8434 Volcanology: Magma migration.

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Citation: Branca, S., D. Carbone, and F. Greco (2003), Intrusive mechanism of the 2002 NE-Rift eruption at Mt. Etna (Italy) inferred through continuous microgravity data and volcanological evidences, Geophys. Res. Lett., 30(20), 2077, doi:10.1029/2003GL018250.