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Menichelli, Irene
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Menichelli, Irene
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- PublicationOpen AccessLithosphere Structure, Processes, and Physical State of the Alpine‐Apennine System(2023-04)
; ; ; ; ; ;; ; ; Abstract Tomographic images of the lithosphere are the first step to constrain the evolution of mountain belts and their interaction. By inverting new high-quality P- and S-wave arrivals that sample the entire lithosphere, we determined Vp and Vp/Vs models with reliable resolution in the critical depth range (40–80 km) where plates of the central Mediterranean area interact. This data set yields homogeneous representation of the 3D structure over a critical area at a regional scale. Here, we show that the Alps derive from a laterally continuous underthrusting of the European plate and that the Adria lithosphere was delaminated after the collision. Tomograms resolve the lateral changes of the continental versus oceanic subduction along the Alpine belt and identify original evidence of fluids beneath the orogens able to facilitate the current deformation. Plain Language Summary A high resolution imaging of the lithosphere/asthenosphere system is crucial to understand tectonic processes of orogens and subductions. The Alpine chain is an exemplary case of complexity, with its lateral heterogeneity and changes. The largest seismic array ever developed in the Alpine chain (Alparray Seismic Network) has enabled the creation of a high-quality seismic data set contributing to new images of the entire central Mediterranean area. The novelty of this work lies in the enhanced resolution of velocity anomalies in a critical depth range (35–80 km) and with optimal homogeneity at the regional scale. The new 3D Vp and Vp/Vs models allow us to get insights into many open questions about the structure and evolution of the circum-Mediterranean orogens.64 45 - PublicationOpen AccessContinental subduction of Adria in the Apennines and relation with seismicity and hazard(2023)
; ; ; ; ; ; ;; ; The subduction of continental lithosphere is a complex process because the buoyancy of the crust is higher than the oceanic and should resist sinking into the mantle. Anyway, studies on the Alpine-Himalayan collision system indicate that a large portion of the continental crust is subducted, while some material is accreted in the orogens. The Apennine is a perfect case for studying how such processes evolve, thanks to high quality seismic images that illuminate a critical depth range not commonly resolved in many collisional settings. In this paper, we show the structure of the Apennines orogen, as jointly revealed by seismicity and deep structure from regional and teleseismic tomography and receiver function profiles. The westward subducting Adria lithosphere is well defined along the orogen showing a mid-crustal delamination. Seismicity within the underthrusting lower crust and velocity anomalies in the mantle wedge highlight how the subduction evolution is entangled with the liberation of fluids. The eclogitization of subducted material enhances the fluid release into the wedge, the delamination and retreat of the Adria plate. This delamination/subduction generates a coupled compression and extension system that migrates eastward following the retreat of the lithosphere, with broad sets of normal faults that invert or interfere with pre-existing compressional structures all over the roof plate. The sparseness and non-ubiquity of intermediate depth earthquakes along the subduction panel suggest that the brittle response of the subducting crust is governed by its different composition and fluid content. Therefore, the lower crust composition appears essential in conditioning the evolution of continental subduction.34 28 - PublicationRestrictedMinimum 1D Vp and Vp/Vs Models and Hypocentral Determinations in the Central Mediterranean Area(2022-06-01)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; Minimum 1D velocity models and station corrections have been computed for the central Mediterranean area using two main data sets. The first one consists of accurate first arrival‐time readings from 103 seismic events with magnitude (ML)≥3.5 recorded by the Italian National Seismic Network (RSN) and the AlpArray Seismic Network (AASN) in the period 2014–2021. Earthquakes were selected on the basis of their spatial distribution, epicentral distance to the nearest seismic station, and maximum distance traveled by Pn and Sn phases. This fine selection of high‐quality data combined with the spatial density of the AlpArray seismic stations was decisive in obtaining high resolution for upper mantle velocity, especially in the Alpine belt. To obtain a denser coverage of crustal rays, we extended the first data set with P and S arrivals of local earthquakes from Istituto Nazionale di Geofisica e Vulcanologia (INGV) bulletin data (2016–2018). A total of 75,807 seismic phases (47,183 P phases and 28,264 S phases) have been inverted to calculate best‐fit 1D velocity models, at regional and local scales. We then test the performance of the optimized velocity models by relocating the last four years of seismicity recorded by INGV (period 2017–2020). The computed velocity models are very effective for routine earthquake location, seismic monitoring, source parameter modeling, and future 3D seismic tomography.259 1