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Presti, Debora
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Presti, Debora
ORCID
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14322490100
5 results
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- PublicationRestrictedThe intra-orogenic normal Lakes Fault (Sila, Calabria, southern Italy): new insights from geodetic and seismological data(2023-07-25)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; The Calabrian Orogenic Arc (COA) is affected by active extensional and strike-slip tectonics as documented by the presence of N-S and NE-SW trending intra-montane basins bordered by faults, whose slip has caused many destructive earthquakes during the last millennium. By focusing on the central sector of the COA (Sila Massif) through the analysis of new seismological and geodetic datasets, we observed some relevant differences (e.g., seismic activity and hypocentral depths, faulting style, geodetic strain, vertical rates) between its western and eastern sector. The transition between the two sectors occurs in the area of the Lakes Fault, a NW-SE striking and west-dipping fault indicated as the causative source of the 8 June 1638 M 6.8 earthquake. By modelling the available geodetic data, we inferred a dislocation plane whose geometry and kinematics (a prevalent dip-slip component coupled with minor left-lateral strike-slip) is compatible with the real fault reported in literature. This fault only accounts for a small amount of the deformation across northern COA and divides the seismically more active western sector from its eastern counterpart with appreciable geodetic strain and moderate seismicity. Results are encouraging and a similar approach can help in other regions where surface evidence of active faults are rare or non-existing and field geological investigations are hence difficult.37 6 - PublicationOpen AccessNew insights on the active degassing system of the Lipari-Vulcano complex (South Italy) inferred from Local Earthquake Tomography(2022-11-07)
; ; ; ; ; ; ; ; ; ; ; Seismic tomography is a very powerful and effective approach to look at depths beneath volcanic systems thus helping to better understand their behaviour. The P-wave and S-wave velocity ratio, in particular, is a key parameter useful to discriminate the presence of gas, fluids and melts. We computed the first 3-D overall model of Vp, Vs and Vp/Vs for the Lipari-Vulcano complex, central sector of the Aeolian volcanic archipelago (southern Italy). The investigated area has been characterized in recent times by fumaroles, hydrothermal activity and active degassing. In particular, in the Vulcano Island, several episodes of anomalous increases of fumarole temperature and strong degassing have been recorded in the past decades and the last "crisis", started in September 2021, is still ongoing. For tomographic inversion we collected ~ 4400 crustal earthquakes that occurred in the last thirty years and we used the LOcal TOmography Software LOTOS. The results clearly depicted two low Vp and Vp/Vs anomalies located up to ~ 8 km depths below Vulcano and the western offshore of Lipari, respectively. These anomalies can be associated to the large presence of gas and they furnish a first picture of the gas-filled volumes feeding the main degassing activity of the area.47 15 - PublicationRestrictedA reappraisal of the 1978 Ferruzzano earthquake (southern Italy) from new estimates of hypocenter location and moment tensor inversion(2019)
; ; ; ; ; ; ; ; ; ; ; The March 11th, 1978 Ferruzzano earthquake is the most recent moderate-to-major earthquake occurred in the southern Calabrian region (southern Italy), one among the highest seismic risk areas of the whole Mediterranean. Previous information available from the literature on the 1978 earthquake is quite contrasting and not well framed in the regional seismotectonic scenario. In the present study we selected and digitized analog seismograms coming from stations of the Euro-Mediterranean region to invert for the deviatoric seismic moment tensor through a time-domain algorithm properly implemented to analyze data recorded before the advent of the digital era. Moreover, we estimated a new hypocentral location by using original bulletin data and a non-linear probabilistic earthquake location technique working with 3D velocity models. The quality and stability of the obtained results, both for hypocenter location and moment tensor inversion, were accurately checked by several inversion tests. Our results indicate that the 1978 earthquake (i) occurred westward and at a shallower depth respect to previous hypocenter locations, (ii) is characterized by a ca. N-S trending normal faulting mechanism and (iii) has a moment magnitude of 4.7, thus suggesting an overestimate of previous evaluations. This study furnishes new information on the 1978 Ferruzzano earthquake allowing to better frame it in the regional seismotectonic scenario and also proves that the time-domain waveform inversion algorithm applied to digitized old seismograms is capable to successfully invert also M w < 5 earthquakes. The obtained results pave the way for future analyses of the early instrumental seismicity potentially capable to furnish new constraints to local and regional seismotectonic modeling.71 3 - PublicationOpen AccessMagmatism Along Lateral Slab Edges: Insights From the Diamante‐Enotrio‐Ovidio Volcanic‐Intrusive Complex (Southern Tyrrhenian Sea)(2019)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ; ; ; ; ; ;Volcanic-Intrusive complexes often formed along lateral slab-edges as a consequence of subduction-induced mantle flow. We investigate this process in the southern Tyrrhenian Sea by integrating multibeam bathymetry, seismic-reflection data, regional magnetic anomalies data, and seismological data. The interpretation of the data highlights the presence of magmatic intrusions that locally reach the seafloor forming volcanic edifices. Chimneys, lava flows, and laccoliths are observed beneath and surrounding the volcanoes. The emplacement and cooling of the magma occurred during the Brunhes Chron. The volcanoes are not active even if the hydrothermal activity occurs. The volcanic-intrusive complex can be subdivided in a western domain (Diamante and Enotrio seamounts) where strike-slip transpressional faults deform the volcanic edifices, and an eastern domain (Ovidio volcanic seamounts) characterized by flat-topped volcanic edifices. The flat-topped morphology is the result of the interplay between volcanism, erosion, sedimentation and sea-level change. The Ovidio volcanic seamounts formed in an area that experienced at least 60 m of subsidence. Magnetic signatures over the northern side of the Ovidio and Diamante seamounts highlight the presence of a deep-rooted, magnetized feeding system remnant. Volcanic edifices extend above a magma feeding system, characterized by low Vp/Vs ratios. The Diamante-Enotrio-Ovidio volcanic-intrusive complex formed as a consequence of the ascent of subduction-induced mantle flow originated in the northern-western edge of the retreating Ionian slab. We speculate that the magma ascent was controlled by a strike-slip deformation belt, which accommodated the bulk of the shear strain resulting from the formation of a roughly E-W trending, Subduction-Transform Edges Propagator fault.325 55 - PublicationRestrictedPresent-day kinematics and deformation processes in the southern Tyrrhenian region: new insights on the northern Sicily extensional belt(2017)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; We performed a new analysis of updated and accurate sets of seismic and GNSS data relative to the southern Tyrrhenian region. Detailed velocity field and crustal strain distribution coming from integration of episodic and continuous measurements at more than 160 geodetic sites (spanning the 1994-2015 period) have been evaluated together with the spatial distribution of recent seismicity and an updated catalogue of waveform inversion fault-plane solutions relative to the period 1976-2014. In agreement with previous investigations, we have found that the kinematics of the study area is quite homogeneous except for the north-eastern corner of Sicily which moves almost coherently with southern Calabria in response to the SE-ward rollback of the Ionian slab. The rest of the study region shows a NNW-trending velocity field in agreement with the direction of the Nubia-Eurasia convergence and it is mainly interested by a major compressive domain. NNW-oriented compression is particularly highlighted by seismic data along the E-W trending seismic belt located in the southern Tyrrhenian Sea. In the framework of such compressive regime, the E-W trending extensional domain of northern Sicily is also clearly depicted both by seismic and geodetic data. The cause of this extensional domain framed inside a mainly compressive one represents an open question in the recent scientific debate. Comparisons between our results and literature information on regional geology and crustal structure led us to investigate whether the extension could occur as local response to the thrusting dynamics of the southern Tyrrhenian belt, favoured by the presence of pre-existing weakness zones. We then propose a first attempt to evaluate such a possible causal relationship by means of Finite Element Method (FEM) and Coulomb Stress Change (CSC) modelling. In particular, we adopted a FEM approach to investigate the deformation pattern produced by thrust faulting of southern Tyrrhenian belt, along a 2D profile crossing both the compressive belt and the extensional one in northern Sicily. We also estimated the CSC due to the thrust faulting on normal receiving faults fairly reproducing pre-existing structures of northern Sicily. Modelling results indicate that the thrust faulting activity along the Southern Tyrrhenian compressive margin could be effective in promoting extensional processes in northern Sicily. We have so shown that the local response to thrust faulting activity may concur, even in combination with other processes, to generate the crustal stretching of northern Sicily.139 8