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Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione Pisa, Pisa, Italia
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Pisa
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INGV Institute
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- PublicationOpen AccessThe Role of Viscoelastic Stress Transfer in Long-Term Earthquake Cascades: Insights After the Central Italy 2016-2017 Seismic SequencCentral Italy is characterized by a network of active faults that interact in a complex manner. Coseismic Coulomb stress changes have been invoked by several authors to explain the concentration of moderate-to-strong earthquakes in this region, but none has considered the time-dependent viscoelastic relaxation of the lower crust and upper mantle as a possible additional source of stress changes at a regional scale. Here starting from the 1915 M-w 6.90.2 Fucino earthquake, we calculated the coseismic plus postseismic Coulomb failure stress changes (CFS) due to eight moderate-to-strong earthquakes that have struck Central Italy in the last century and culminated with the 2016-2017 sequence. Results from this modeling coupled with some synthetic tests simulating normal fault earthquakes with different magnitudes allowed us to highlight the importance of postseismic processes. In particular, the viscoelastic stress transfer due to events of M-w >= 6.5 can modify the spatial distribution of CFS on a centennial timescale and therefore trigger events at larger distances. In addition, using these results, we identified other earthquake clusters in the historical catalogue (last 618 years), which, like the 1915-2017 series, were potentially modulated by both coseismic and postseismic processes. Finally, considering our calculations combined with historical and paleoseismological data, we suggest that several faults in Central Italy may be at present close to failure.
255 49 - PublicationRestrictedThe forgotten eruption: The basaltic scoria cone of Montaña Grande, Tenerife(2020)
; ; ; ; ; ; ; ; ; ; ; We report on the Strombolian to Violent Strombolian eruption of Montaña Grande which occurred between 789 and 725 BCE in the Güimar Valley on the NE flank of Tenerife island. The eruption produced a ca. 180 m-high sco- ria cone, a thick fallout deposit mostly dispersed southwest and a vast lava flow field that extends east of the cone, towards the coast, for 3.3 × 2.2 km. The eruption occurred in an unusual geodynamic context, outside the North West Rift and North East Rift zones and out of Las Cañadas caldera which are the main geological structures of Tenerife, where the volcanic activity concentrated during the Holocene. The tephra and lava have a trachybasalt composition similar to products of the recent activity of Tenerife but characterized by a distinct trace element pattern (Ta depletion relative to Nb), that points to a distinct source for the magma feeding the eruption and an ascent history along the whole crust which is independent and different from the central feeding system of the Teide-Pico Viejo volcanic complex. The study of this eruption, which until now had been completely neglected, adds new significant data for the correct definition of volcanic risk in Tenerife.1064 5 - PublicationRestrictedThe Vegetation Resilience After Fire (VRAF) index: Development, implementation and an illustration from central Italy(2008)
; ; ; ; ; ;Bisson, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Fornaciai, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Coli, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Mazzarini, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Pareschi, M. T.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; ; ; ; A suitable index is proposed to evaluate the natural short–medium-term recovery capability of vegetation in burnt areas. The study area covers 2450 km2 in western Tuscany (Province of Pisa, Italy). This region is characterized by a typical Mediterranean climate and is subject to fire damage during the dry summer season. Damage is mitigated where a natural rapid regrowth of vegetation prevents soil erosion, supporting the return to a natural pre-fire state. The Vegetation Resilience After Fire (VRAF) index is based on the vegetation association, soil type and geology, and on morphological features such as slope and aspect. The results are proposed as georeferenced maps defining areas with different vegetation resilience for both high and medium burn severity. The VRAF maps estimate the natural ability of vegetation to recover after fire, and suggest where human intervention is required to improve this capability. The VRAF index was checked by monitoring vegetation regrowth after fire in three burnt areas over a five-year period using spectral signatures, the feature space and the NDVI derived from remote sensing data. This analysis indicates that the high values of the VRAF index correspond to a recovery period of almost three years. Field surveys were performed to further test the results. On the whole, the VRAF index is a good parameter for assessing the capability of vegetation to recover in northern Mediterranean areas.158 14 - PublicationRestrictedPhysical modelling and human survival in pyroclastic flows(1998)
; ; ; ; ;Volcanic eruptions increasingly present catastrophic natural risks with hundreds of mil- lions of people now living in areas of active volcanism and major conurbations around active eruptive centres. Interdisciplinary studies in disaster reduction have an important role in volcanic emergency management through advancing our understanding of the physical impacts of eruptive phenomena and the causes of death and injury in explosive eruptions. Numerical modelling of pyroclastic flows, amongst the most destructive of eruptive phenomena, provides new opportunities to improve the evaluation of the potential destructiveness of volcanic events and their human impacts in densely populated areas. In this work, the results of numerical modelling of pyroclastic flow propagation at Vesuvius have been analysed in terms of the physical parameters (temperature, ash in air concentra- tion, and dynamic pressure) that are most critical for human survival. Our numerical simulations of eruptions of Vesuvius indicate that a large area exists where total destruction may not be inevitable in small to medium scale events, a finding that has prompted us to explore further the implications for human survival as part of an interdisciplinary approach to disaster reduction. The lessons of mod- elling at Vesuvius should be integrated into civil protection plans for other urban centres threatened by volcanoes.76 4 - PublicationRestrictedA parallel multiphase flow code for the 3D simulation of explosive volcanic eruptions(2007-08)
; ; ; ; ; ;Esposti Ongaro, T.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Cavazzoni, C.; CINECA, Interuniversity Computing Centre, Casalecchio di Reno (BO), Italy ;Erbacci, G.; CINECA, Interuniversity Computing Centre, Casalecchio di Reno (BO), Italy ;Neri, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Salvetti, M. V.; Dip.to di Ingegneria Aerospaziale, Università degli Studi di Pisa, Pisa, Italy - Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa, Pisa, Italy; ; ; ; A new parallel code for the simulation of the transient, 3D dispersal of volcanic particles in the atmosphere is presented. The model equations, describing the multiphase flow dynamics of gas and solid pyroclasts ejected from the volcanic vent during explosive eruptions, are solved by a finite-volume discretization scheme and a pressure-based iterative non-linear solver suited to compressible multiphase flows. The solution of the multiphase equation set is computationally so demanding that the simulation of the transient 3D dynamics of eruptive columns would not be cost-effective on a single workstation. The new code has been parallelized by adopting an ad hoc domain partitioning scheme that enforces the load balancing in the presence of a large number of topographic blocking-cells. An optimized communication layer has been built over the Message-Passing Interface. It is shown that the present code has a remarkable efficiency on several high-performance platforms and makes it possible, for the first time, to simulate fully 3D eruptive scenarios on realistic volcano topography.175 30 - PublicationRestrictedAbsolute gravity acceleration measurement in atomic sensor laboratories(2012)
; ; ; ; ; ; ; ; ;de Angelis, M.; Istituto di Fisica Applicata “Nello Carrara” CNR, Sesto Fiorentino, Italy. ;Greco, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Pistorio, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Poli, N.; Dipartimento di Fisica and LENS, Università di Firenze-INFN, Sesto Fiorentino (FI), Italy ;Prevedelli, M.; Dipartimento di Fisica, Università di Bologna, Bologna, Italy ;Saccorotti, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Sorrentino, F.; Dipartimento di Fisica and LENS, Università di Firenze-INFN, Sesto Fiorentino (FI), Italy ;Tino, G. M.; Dipartimento di Fisica and LENS, Università di Firenze-INFN, Sesto Fiorentino (FI), Italy; ; ; ; ; ; ; This paper reports the results from the accurate measurement of the acceleration of gravity g taken at two separate premises in the Polo Scientifico of the Florence University (Italy). In these laboratories, two separate experiments aiming at measuring the Newtonian constant and testing the measurement of forces with high spatial resolution are in progress. Both experiments require an independent knowledge on the local value of g. Gravity measurements were conducted using an FG5 absolute gravimeter, and accompanied by seismic recordings for evaluating the noise condition at the site. The absolute accelerations of gravity at the two laboratories are (980 492 160.6 ± 4.0) μGal and (980 492 048.3 ± 3.0) μGal for the European Laboratory for Non-Linear Spectroscopy (LENS) and Dipartimento di Fisica e Astronomia, respectively. Other than for the two referenced experiments, the data here presented will serve as a benchmark for any future study requiring an accurate knowledge of the absolute value of the acceleration of gravity in the study region.301 25 - PublicationRestrictedTexture analysis of volcanic rock samples: Quantitative study of crystals and vesicles shape preferred orientation from X-ray microtomography data(2011-04-30)
; ; ; ; ;Voltolini, M.; Sincrotrone Trieste, Basovizza (TS), Italy ;Zandomeneghi, D.; International Centre for Theoretical Physics, Trieste, Italy ;Mancini, L.; Sincrotrone Trieste, Basovizza (TS), Italy ;Polacci, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; ; ; In the texture analysis of volcanic rocks, the preferred orientation of the constituents can provide useful information for the interpretation of the processes involved in the rock formation. We present here a new data analysis technique, based on X-ray microtomography measurements and on shape preferred orientation analysis, to obtain the orientation distribution functions of the constituents of volcanic rocks. This procedure proved to be very suitable for volcanic samples, where diffraction-based techniques, developed for crystallographic preferred orientation studies, are of limited utilization, in addition to the fact that they cannot provide any information about vesicles or bubbles. Moreover the analysis performed directly in three dimensions (3D) overcomes the problems that usually occur when employing stereological methods for the analysis of the images obtained via microscopy-based techniques. In this study, two scoriae (from Stromboli and Etna) and a tube pumice (from Campi Flegrei) were measured via X-ray microtomography and then the resulting volumes were analyzed following the proposed procedure. Results highlight little preferred orientation for the vesicles in the two scoria samples, whereas the pumice shows a marked preferred orientation. Crystals (also divided by mineral species) were taken into account as well and in the two scoria samples there is no crystal preferred orientation, in contrast with the pumice, where crystal preferred orientation features are very similar to the ones found for the vesicles. Overall we found strong differences in preferred orientation: weak for vesicles in scoriae, showing an axial symmetry with the axis parallel to the elongation axis of the sample, and a stronger and more complex orientation texture in the pumice sample for both crystals and vesicles. The promising results obtained suggest that this procedure is potentially very useful for the analysis of preferred orientation in volcanic rocks and geomaterials in general.138 22 - PublicationOpen AccessPM10 measurements in urban settlements after lava fountain episodes at Mt. Etna, Italy: pilot test to assess volcanic ash hazard to human health(2016)
; ; ;Andronico, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Del Carlo, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; We have carried out a preliminary study on the potential risks caused by the sub-10 mu m fraction of volcanic ash (particulate matter, PM10) after the basaltic explosive eruptions from Mt. Etna volcano (Italy), which have dramatically increased in frequency over the last 20 years. We present results deriving from the study of the ash concentration in the air following the lava fountain episode from the New Southeast Crater of Etna on 15 November 2011, which caused tephra fallout over the eastern slope of the volcano. Short-duration tests of PM10 measurements were carried out at three different sites using a TSI (R) DustTrak (TM) aerosol monitor a few hours after the end of the eruption, and readouts of the air quality were repeated at the same sites a month later without volcanic activity. Furthermore, ash samples were characterized by grain size, componentry and morphological and petrochemical analyses. By comparing PM10 levels measured a few hours after the 15 November lava fountain and on 15 December, we found that relatively low amounts (500-1500 gm(-2)) of tephra fallout cause high levels of PM10 in the air. This is because the coarse particles, particularly basaltic ash, are readily broken up by traffic and hence remobilized into the air. We believe the impact from ash fallout in the Etnean territory should receive greater attention, especially regarding potential health problems. Simple but effective actions can be implemented to reduce eventual risks, first and foremost the prompt removal of the ash deposits from the urbanized areas.379 421 - PublicationRestrictedNew bio-magnetostratigraphic data on the Miocene Moria section (Northern Apennines, Italy): connections between the Mediterranean region and the North Atlantic Ocean(2015)
; ; ; ; ; ; ; ; ; ; ; ; ; New bio-magnetostratigraphic data have been acquired from the Burdigalian part of the Moria section in the Umbria–Marche Apennine (Central Italy). The investigated sedimentary sequence is 55 meters thick and comprises the transition between the Bisciaro and the Schlier formations (Auctorum), composed of five meters of indurated marly limestones, followed by about 40 meters of blue marly clays capped by 10m of alternating clays and calcareous layers. According to existing literature, the sequence contains the so-called “Piero della Francesca Level” (Auctorum), a few-centimeters-thick biotite-rich level. The sequence has been sampled for paleomagnetic and calcareous plankton analyses. Four magnetic polarity zones have been documented in the middle and upper part of the section. The calcareous plankton content shows different degrees of preservation, from poor to good for calcareous nannofossils and poor to medium for planktonic foramini- fers. Several useful biohorizons have been observed and chronologically constrained through calibration to the magnetostratigraphic data. The studied section ranges from the top of Chron C5Dr.1n to Chron C5Cn.2r, covering the time interval from 17.7 to 16.4Ma (according to the ATNTS04) almost continuously, with a small hiatus of at least 34ka at the C5Dn/C5Cr transition. The integration of our results with those from previous studies of the same section and comparisons with data from other Mediterranean and North Atlantic sequences allows to evaluate the synchrony of the observed biohorizons with other parts of the Mediterranean and the Atlantic Ocean during a still relatively poorly known time interval.243 5 - PublicationOpen AccessELICIPY 1.0: A Python online tool for expert elicitation(2024)
; ; ; ; ; ; ; Structured expert judgment is crucial when dealing with significant epistemic and aleatoric uncertainties, particularly in probabilistic hazard assessments, where decisions based on uncertain information are often critical. In structured expert elicitations, participants are asked to quantify their uncertainty judgments by providing their percentile estimates of numerical values for a set of questions. More specifically, performance-based elicitations start with ‘‘seed’’ questions for determining experts’ uncertainty quantification skill. The performance scores are thus used to define each expert’s weight to be applied when considering their judgments on ‘‘target’’ questions, i.e., the actual variables of interest for the case study. In this paper we describe ELICIPY, a new Python tool which allows to perform expert elicitation sessions in a framework that covers both the questionnaire collection and the analysis parts, an approach that simplifies the work normally done by the analyst(s). This is achieved through the automatic generation of online webforms to collect the experts’ answers, their check for consistency and, finally, their analysis using different weighting schemes. The tool automatically produces outputs in different formats and creates a pptx presentation file available just after the collection of the answers.65 8