http://hdl.handle.net/2122/277 Search the Channel search http://www.earth-prints.org/simple-search http://hdl.handle.net/2122/4156 Title: Paleo-environmental and volcano-tectonic evolution of the southeastern £ank of Mt. Etna during the last 225 ka inferred from the volcanic succession of the ‘Timpe’, Acireale, Sicily <br/> <br/>Authors: Corsaro, R. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Neri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Pompilio, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia <br/> <br/>Abstract: The tectonic escarpments locally known as ‘Timpe’ cut a large sector of the eastern flank of Etna, and allow an ancient volcanic succession dating back to 225 ka to be exposed. Geological and volcanological investigations carried out on this succession have allowed us to recognize relevant angular unconformities and volcanic features which are the remnants of eruptive fissures, as well as important changes in the nature, composition and magmatic affinity of the exposed volcanics. In particular, the recognition in the lower part of the succession of important and unequivocal evidence of ancient eruptive fissures led us to propose a local origin for these volcanics and to revise previous interpretations which attributed their westward-dipping to the progressive tectonic tilting of strata. These elements led us to reinterpret the main features of the volcanic activity occurring since 250 ka BP and their relationship with tectonic structures active in the eastern flank of Etna. We propose a complex paleo-environmental and volcanotectonic evolution of the southeastern flank of Mt. Etna, in which the Timpe fault system played the role of the crustal structure that allowed the rise and eruption of magmas in the above considered time span. Mon, 29 Oct 2001 22:58:59 GMT http://hdl.handle.net/2122/4155 Title: Volumetric observations during paroxysmal eruptions at Mount Etna: pressurized drainage of a shallow chamber or pulsed supply? <br/> <br/>Authors: Harris, A. J. L.; HIGP/SOEST, University of Hawaii, 2525 Correa Road, Honolulu, HI 96822, USA; Neri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia <br/> <br/>Abstract: The October 17 to November 5, 1999, eruption of Mount Etna’s Bocca Nuova crater emplaced a V15U106 m3 flow field. The eruption was characterized by 11 paroxysmal events during which intense Strombolian and lava fountain activity fed vigorous channelized PaPa flows at eruption rates of up to 120 m3 s31. Each paroxysm lasted between 75 and 450 min, and was separated by periods of less intense Strombolian activity and less vigorous (610 m3 s31) effusion. Ground-based, satellite- and model-derived volumetric data show that the eruption was characterized by two periods during which eruption rates and cumulative volume showed exponential decay. This is consistent with a scenario whereby the system was depressurized during the first eruptive period (October 17^23), repressurized during an October 24 pause, and then depressurized again during the second period (October 25^28). The imbalance between the erupted and supplied volumes mean that the two periods involved the collection of 1.5^5.7U106 m3 and 1.2^ 3.6U106 m3, respectively, or an increase in the time-averaged supply to 11.6^13.6 m3 s31 and 12.5^14.9 m3 s31. Two models are consistent with the observed episodic fountaining, derived volumetric trends and calculated volume imbalance: a magma collection model and a pulsed supply model. In the former case, depressurization of a shallow reservoir cause the observed volumetric trends and foam collapse at the reservoir roof powers fountaining. In the pulsing case, variations in magma flux account for pressurization^depressurization and supply the excess volume. Increases in rise rate and volatile flux, coupled with rapid exsolution during ascent, trigger fountaining. Limiting equations that define critical foam layer volumes and magma rise rates necessary for Hawaiian-style fountaining favor the latter model. Mon, 29 Oct 2001 22:58:59 GMT http://hdl.handle.net/2122/4154 Title: Link between major flank slip and 2002–2003 eruption at Mt. Etna (Italy) <br/> <br/>Authors: Acocella, V.; Dip. Scienze Geologiche Roma TRE. L. S.L. Murialdo, Roma, Italy; Behncke, B.; Dip. Scienze Geologiche, Univ. Catania, Corso Italia, Catania, Italy; Neri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; D'Amico, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia <br/> <br/>Abstract: The 2002–2003 Etna eruption is studied through earthquake distributions and surface fracturing. In September 2002, earthquake-induced surface rupture (sinistral offset 0.48 m) occurred along the E-W striking Pernicana Fault (PF), on the NE flank. In late October, a flank eruption accompanied further ( 0.77 m) surface rupturing, reaching a total sinistral offset of 1.25 m; the deformation then propagated for 18 km eastwards to the coastline (sinistral offset 0.03 m) and southwards, along the NW-SE striking Timpe (dextral offset 0.04 m) and, later, Trecastagni faults (dextral offset 0.035 m). Seismicity (<4 km bsl) on the E flank accompanied surface fracturing: fault plane solutions indicate an overall ESEWNWextension direction, consistent with ESE slip of the E flank also revealed by ground fractures. A three-stage model of flank slip is proposed: inception (September earthquake), climax (accelerated slip and eruption) and propagation (E and S migration of the deformation). Fri, 26 Dec 2003 22:58:59 GMT http://hdl.handle.net/2122/4153 Title: What makes flank eruptions? The 2001 Etna eruption and its possible triggering mechanisms <br/> <br/>Authors: Acocella, V.; Dip. Scienze Geologiche Roma TRE, Largo S.L. Murialdo 1, 00146 Roma, Italy; Neri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia <br/> <br/>Abstract: Most flank eruptions within a central stratovolcano are triggered by lateral draining of magma from its central conduit, and only few eruptions appear to be independent of the central conduit. In order to better highlight the dynamics of flank eruptions in a central stratovolcano, we review the eruptive history of Etna over the last 100 years. In particular, we take into consideration the Mount Etna eruption in 2001, which showed both summit activity and a flank eruption interpreted to be independent from the summit system. The eruption started with the emplacement of a ~N-S trending peripheral dike, responsible for the extrusion of 75% of the total volume of the erupted products. The rest of the magma was extruded through the summit conduit system (SE crater), feeding two radial dikes. The distribution of the seismicity and structures related to the propagation of the peripheral dike and volumetric considerations on the erupted magmas exclude a shallow connection between the summit and the peripheral magmatic systems during the eruption. Even though the summit and the peripheral magmatic systems were independent at shallow depths (<3 km b.s.l.), petro-chemical data suggest that a common magma rising from depth fed the two systems. This deep connection resulted in the extrusion of residual magma from the summit system and of new magma from the peripheral system. Gravitational stresses predominate at the surface, controlling the emplacement of the dikes radiating from the summit; conversely, regional tectonics, possibly related to N-S trending structures, remains the most likely factor to have controlled at depth the rise of magma feeding the peripheral eruption. Wed, 05 Mar 2003 22:58:59 GMT