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Cristofolini, R.
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- PublicationOpen AccessCharacteristics of volcanic tremor accompanying the September 24th, 1986 explosive eruption of Mt. Etna (Italy)(1996-03)
; ; ; ;Gresta, S.; Istituto di Geologia e Geofisica, Università di Catania, Italy ;Lombardo, G.; Istituto di Geologia e Geofisica, Università di Catania, Italy ;Cristofolini, R.; Istituto di Scienze della Terra, Università di Catania, Italy; ; Features of the volcanic tremor recorded before, during and after the eruptive event which occurred at Mt. Etna on September 24th 1986, are described. The whole eruption was particularly short in time (about eight hours) and characterized by an extremely violent explosive activity with lava fountains a few hundred meters high. As the complete record of the seismic signals generated during the whole eruptive episode was available, a detailed spectral analysis of the volcanic tremor recorded at four stations, located at increasing distance from the summit of the volcano, was carried out. Fourier analysis, that was performed using temporal windows of about 11 min in duration, pointed to some large fluctuations of the overall spectral amplitude, as well as some frequency variations of the dominant spectral peaks. The ratio of the overall spectral amplitude recorded at the highest station and at the peripheral ones, was calculated in the two spectral bands 1.0-2.5 and 2.6-6.0 Hz, respectively. The significant contribution of energy at low frequency values supports the hypothesis of a subvertical planar source, which was active during the paroxysmal stage of the eruption. Such results are also supported by the analysis of the attenuation function of the spectral amplitude.168 168 - PublicationRestrictedThe 1669 eruption at Mount Etna: chronology, petrology and geochemistry, with inferences on the magma sources and ascent mechanism(1996)
; ; ; ;Corsaro, R. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Cristofolini, R.; Catania University ;Patanè, L.; Catania University; ; Analysis of the petrochemical characters of the 1669 Etnean lavas shows that they can be grouped into two sets: SET1 lavas were erupted from 11 to 20 March and are more primitive in composition than SET2, erupted later until the end of activity. Both sets may be interpreted as the result of crystallization under different conditions of two primary magmas which are compositionally slightly distinct and which fractionate different volumetric proportions of minerals. To explain why more mafic lavas (SET1) were erupted earlier than more acid ones (SET2), we argue that new deeper magma rose up into a reservoir where residing magma was fractionating. Density calculations demonstrate that new magma is less dense and may originate a plume, rapidly rising through the residing magma which is cooler and more volatile-depleted than the new magma. Calculations of uprise velocity assuminglaminar flow are consistent with this hypothesis261 72 - PublicationRestrictedQuantifying probabilities of eruption at a well-monitored active volcano: an application to Mt.Etna (Sicily, Italy),(2012-03)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Brancato, A.; Universita di Catania ;Gresta, S.; Universita di Catania ;Sandri, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Selva, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Marzocchi, W.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Alparone, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Andronico, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Bonforte, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Caltabiano, T.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Cocina, O.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Corsaro, R. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Cristofolini, R.; Universita di Catania ;Di Grazia, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Distefano, G.; Universita di Catania ;Ferlito, C.; Universita di Catania ;Gambino, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Giammanco, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Greco, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Napoli, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Tusa, G.; Universita di Catania ;Viccaro, M.; Universita di Catania; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; At active volcanoes, distinct eruptions are preceded by complex and different precursory patterns; in addition, there are precursory signals that do not necessarily lead to an eruption. The main purpose of this paper is to present an unprecedented application of the recently developed code named BET_EF (Bayesian Event Tree_Eruption Forecasting) to the quantitative estimate of the eruptive hazard at Mt. Etna volcano. We tested the model for the case history of the July-August 2001 flank eruption. Anomalies in geophysical, geochemical and volcanological monitoring parameters were observed more than a month in advance of the effective onset of the eruption. As a consequence, eruption probabilities larger than 90% were estimated. An important feature of the application of BET_EF to Mt. Etna was the probabilistic estimate of opening vent locations. The methodology allowed a clear identification of assumptions and the monitoring of parameter thresholds and provided rational means for their revision if new data or information are incoming.598 34 - PublicationOpen AccessApplication of BET_EF to Mount Etna: a retrospective analysis (years 2001-2005)(2011)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Brancato, A.; Università di Catania, Dip. Scienze Geologiche ;Gresta, S.; Università di Catania, Dipartimento di Scienze Geologiche ;Alparone, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Andronico, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Bonforte, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Caltabiano, T.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Cocina, O.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Corsaro, R. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Cristofolini, R.; Università di Catania, Dipartimento di Scienze Geologiche ;Di Grazia, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Distefano, G.; Università di Catania, Dipartimento di Scienze Geologiche ;Ferlito, C.; Università di Catania, Dipartimento di Scienze Geologiche, ;Gambino, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Giammanco, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Greco, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Napoli, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Sandri, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Selva, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Tusa, G.; Università di Catania, Dipartimento di Scienze Geologiche ;Viccaro, M.; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; Advances in volcano monitoring and forecasting need a multidisciplinary collaborative framework. In light of this, a Bayesian Event Tree (BET) approach was performed by the application of the BET for Eruption Forecasting (BET_EF) code to analyze the space-time distribution of the volcanic activity of Mount Etna from 2001-2005. First, a reliable monitoring dataset was set up after some sessions to elicit geophysical, volcanological and geochemical ‘precursor’ parameters. A constant unrest probability of 100%, with a magma involvement usually greater than 95%, was computed throughout the time period analyzed. Eruption probabilities higher than 90% were estimated a few days before the onsets of the 2001 and 2002-2003 flank eruptions. Values slightly higher than 75% were observed during the lava fountaining period in June-July 2001. However, the probabilities flattened to around 30% for the 2004-2005 flank eruption. With suitable data, a good depiction of the actual location of the eruptive scenario for the 2001 and 2002-2003 events was provided. Conversely, the size of the eruptions was not indicated.412 432 - PublicationRestrictedSubaqueous volcanism in the Etnean area: evidence for hydromagmatic activity and regional uplift inferred from the Castle Rock of Acicastello(2000)
; ; ;Corsaro, R. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Cristofolini, R.; Catania University; The subalkaline rocks outcropping at the Acicastello Castle Rock, Catania, Sicily, and on its abrasion platforms, are related to the oldest Etnean volcanism 500–300 ka; Here, submarine lavas with pillows closely packed onto each other are associated with heterogeneous and poorly sorted volcaniclastic breccia levels with sub-vertical sharp w boundaries. The present-day attitude was previously interpreted as due to a local tilt or to the seaward sliding of the entire eastern Etnean flank , on the assumption of originally horizontal boundaries. On the contrary, our observations do not match the hypothesis of a significantly tilted succession and lead us to conclude that, apart from the strong regional uplift, the present Castle Rock exposure did not suffer any substantial change of its attitude.121 26 - PublicationRestrictedOrigin and differentiation of recent basaltic magmas from Mount Etna(1996)
; ; ;Corsaro, R. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Cristofolini, R.; Catania University; One hundred and fifty samples of recent Na-alkalic lavas from the south-eastern flank of Mt. Etna, dating from about 5,000 years B.P. to 1886 were analyzed. They grade in time from more acid to more basic lavas, and show an overall range of variation much larger toward the more felsic end than previously known. Chondrite-normalized REE patterns of the least differentiated samples show LREE enrichment and HREE depletion; trace dement compositions suggest that Etnean products are similar to WPB, with a weak CAB signature. Sr-isotope ratios ranging from 0.70332 to 0.70355, vary even within samples from the same eruption, and generally tend to increase with time in historic lavas. Our data suggest that processes other than simple crystal fractionation are, in part, responsible for the variation of the analyzed sequence. In fact, RTF processes with successive influxes of mafic melts, each having distinct, slightly different geochemical and isotopic features, into reservoirs of variously differentiated magmas, may explain the overall observed data. The source region for Recent Mongibello lavas is located in the mantle, isotopically zoned, and Rb-depleted with respect to the Bulk Earth composition. Model and experimental data conform well with a low degree (< 5%) modal melting of a garnet lherzolite source, depleted by an earlier melting event with respect to primitive mantle composition.134 36