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Seconda Università degli Studi di Napoli
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- PublicationOpen AccessA detailed analysis of some local earthquakes at Somma-Vesuvius(1999-06)
; ; ; ; ; ; ;Capuano, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Coppa, U.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;De Natale, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Di Sena, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Godano, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Troise, C.; Dipartimento di Geofisica e Vulcanologia, Università di Napoli "Federico II", Napoli, Italy; ; ; ; ; In this paper, we analyze local earthquakes which occurred at Somma-Vesuvius during two episodes of intense seismic swarms, in 1989 and 1995 respectively. For the selected earthquakes we have computed accurate hypocentral locations, focal mechanisms and spectral parameters. We have also studied the ground acceleration produced by the largest events of the sequences (ML 3.0), at various digital stations installed in the area during the periods of higher seismic activity. The main result is that seismicity during the two swarm episodes presents similar features in both locations and focal mechanisms. Strong site dependent effects are evidenced in the seismic radiation and strong amplifications in the frequency band 10-15 Hz are evident at stations located on the younger Vesuvius structure, with respect to one located on the ancient Somma structure. Furthermore, seismic stations show peak accelerations for the same events of more than one order of magnitude apart.197 360 - PublicationOpen AccessEvaluation of the b Maps on the Faults of the Major (M > 7) South California Earthquakes(2024)
; ; ; ; ; We use the Godano et al. (2022, https://doi.org/10.1029/2021ea002205) method for evaluating the b maps of the faults associated with the largest earthquakes M ≥ 7.0 that occurred in California. The method allows an independent evaluation of the b parameter, avoiding the overlap of the cells and the omission of some earthquakes, while keeping all the available information in the catalog. We analyzed four large earthquakes: Landers, Hector Mine, Baja California, and Searles Valley. The maps obtained confirm that the b value can be considered as a strain meter and allow us to elucidate the presence of barriers, such as obstacles to the propagation of the fracture, on the fault of the analyzed earthquakes. A further estimated parameter is the time window during which aftershocks occur in the cell, Δt. This quantity is very useful for a better definition of the aftershock generation mechanism. It reveals where the stress is released in a short time interval and how the complexity of the faulting process controls the occurrence of aftershocks on the fault, and also the duration of the entire sequence.25 2 - PublicationOpen AccessSubduction age and stress state control on seismicity in the NW Pacific subducting plate(2022)
; ; ; ; ; ; ; Intermediate depth (70-300 km) and deep (>300 km) earthquakes have always been puzzling Earth scientists: their occurrence is a paradox, since the ductile behavior of rocks and the high confining pressure with increasing depths would theoretically preclude brittle failure and frictional sliding. The mechanisms proposed to explain deep earthquakes, mainly depending on the subducting plate age and stress state, are generally expressed by single parameters, unsuitable to comprehensively account for differences among distinct subduction zones or within the same slab. We analyze the Kurile and Izu-Bonin intraslab seismicity and detail the stress state along the subducted planes using the Gutenberg-Richter b-value. We demonstrate that, despite the slabs different properties (e.g., lithospheric age, stress state, dehydration rate), in both cases deep earthquakes are restricted to depths characterized by equal age from subduction initiation and are driven by stress regimes affected by the persistence of the metastable olivine wedge.320 6 - PublicationOpen Accessb value enlightens different rheological behaviour in Campi Flegrei caldera(2024)
; ; ; ; ; The Campi Flegrei caldera is one of the most dangerous volcanoes in the world and since 2005 it is in unrest. Here we evaluate the 3D tomography of the b value at the Campi Flegrei volcanic area revealing a very good correlation with the structure of the hydrothermal system involved in the bradiseismic phenomenon. More precisely, we observe the smallest b-values where we expect the higher stress/strain concentration, namely in the caprock, and for the deepest seismicity. Conversely, the largest b values are observed where the porosity of the medium allows the passage of the volcanic gases toward the surface. Values of b close to typical tectonic ones are observed where the presence of faulting structures is well documented.125 1 - PublicationRestrictedUpwards migration of seismic focii: A forerunner of the 1989 eruption of Mt Etna (Italy)(1993)
; ; ; ; ; ;Castellano, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Ferrucci, F.; Università della Calabria ;Godano, C.; Seconda Università degli Studi di Napoli ;Imposa, S.; Università di Catania ;Milano, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; ; ; ; In the text156 20 - PublicationRestrictedMechanical origin of aftershocks(2015)
; ; ; ; ; ; ; ; ; Aftershocks are the most striking evidence of earthquake interactions and the physical mechanisms at the origin of their occurrence are still intensively debated. Novel insights stem from recent results on the in influence of the faulting style on the aftershock organisation in magnitude and time. Our study shows that the size of the aftershock zone depends on the fault geometry. We find that positive correlations among parameters controlling aftershock occurrence in time, energy and space are a stable feature of seismicity independently of magnitude range and geographic areas. We explain the ensemble of experimental findings by means of a description of the Earth Crust as an heterogeneous elastic medium coupled with a Maxwell viscoelastic asthenosphere. Our results show that heterogeneous stress distribution in an elastic layer combined with a coupling to a viscous flow are sufficient ingredients to describe the physics of aftershock triggering.69 1 - PublicationOpen AccessStruttura crostale delle aree vulcaniche attive dell'Italia meridionale da indagini di sismica attiva (DSS) e passiva: area vulcanica campana; Isole Eolie meridionali(1988)
; ; ; ; ; ; ; ;Castellano, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Ferrucci, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Gaudiosi, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Godano, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Milano, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Pino, N. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Vilardo, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; ; ; ; ; ; In the text289 187 - PublicationOpen AccessSpatial and temporal distribution of vertical ground movements at Mt. Vesuvius in the period 1973-2009(2013)
; ; ; ; ; ; ; ;Pingue, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Bottiglieri, M.; Seconda Università di Napoli ;Godano, C.; Seconda Università di Napoli ;Obrizzo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Tammaro, U.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Esposito, T.; Università Federico II, Napoli ;Serio, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; ; ; ; ; ; Since the early ’70s vertical ground movements at Mount Vesuvius area have been investigated and monitored by the Osservatorio Vesuviano (Istituto Nazionale di Geofisica Vulcanologia - Osservatorio Vesuviano since 2001). This monitoring began with the installation of a high-precision leveling line in the region at medium-high elevations on the volcano. The deformation pattern and expected strain field assessment methods in the volcanic structure induced by inner sources has demanded in subsequent years the expansion of the leveling network up to cover the whole volcanic area, enclosing part of leveling lines of other institutions. As a result of this expansion, the Mt. Vesuvius Area Leveling Network (VALN) has today reached a length of about 270 km and consists of 359 benchmarks. It is configured in 21 circuits and is connected, westward, to the Campi Flegrei leveling network and, northward, to the Campania Plain leveling network. The data collected have been carefully re-analyzed for random and systematic errors and for error propagation along the leveling lines to identify the areas affected by significant ground movements. For each survey, the data were rigorously adjusted and vertical ground movements were evaluated by differentiating the heights calculated by the various measurements conducted by the Osservatorio Vesuviano from 1973 to 2009.349 471 - PublicationOpen AccessNonlinear convective motion of the asthenosphere and the lithosphere melting: a model for the birth of a volcanoThe processes of heat transfer occurring between the Earth’s asthenosphere and lithosphere are responsible for partial melting of rocks, leading to the magma generation and its migration and segregation in the crust and, possibly, to volcanoes generation at the surface. Convection is the dominant mechanism regulating the heat transfer from the asthenosphere to the lithosphere, although many aspects of the whole process are not yet clear. Therefore, the knowledge of the physical processes leading to the melting of the lithospheric rocks has important consequences in understanding the interior Earth dynamics, the surface volcanic dynamics, and its related hazards. Rock melting occurs when the temperature gradient meets the rock solidus. Here, we propose a nonlinear convective 1D analytical model (representing an approximation of more 3D complex models). The steady-state solution of our equation is in good agreement with the estimated geotherms of the asthenosphere. A perturbative approach leads to a heat swelling at the boundary between asthenosphere and lithosphere able to determine its melting and the birth of a volcano.
134 7 - PublicationRestrictedParameter Estimation in the ETAS Model: Approximations and Novel Methods(2014)
; ; ; ; ; ;Lippiello, E.; Second University of Naples ;Giacco, F.; Second University of Naples ;De Arcangelis, L.; Second University of Naples ;Marzocchi, W.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Godano, C.; Second University of Naples; ; ; ; Branching processes provide an accurate description of earthquake occurrence in the short term (days to a few weeks). Yet, the implementation of these models is not usually straightforward because of the difficulties in estimating the parameters. Indeed, log-likelihood estimation involves a spatial integral that cannot be analytically evaluated and is difficult to implement in numerical codes. Here we present a novel technique that allows for an accurate, stable, and relatively fast param- eter inversion procedure. We study the efficiency of this technique using synthetic epidemic-type aftershock sequence catalogs with a set of parameters known a priori. Results show the efficiency of the novel technique and illustrate the limits of recently proposed approximations147 26
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