Seismic expression of the shallow structure of The Neapolitan Yellow Tuff (NYT) caldera offshore the Campi Flegrei

In this study we integrate high-resolution swath bathymetry, single-channel reflection seismic data and gravity core data, to provide new insights into the shallow structure and latest Quaternary to Holocene evolution of the submerged sector of the Neapolitan Yellow Tuff (NYT) caldera (Campi Flegrei) in the Pozzuoli Bay. The new data allow for a reconstruction of the offshore geometry of the NYT caldera collapse \u2013 ring fault system, along with the style and timing of deformation of the inner caldera resurgence. Our interpretation shows that the NYT eruption (~15 ka BP) was associated with a caldera collapse bounded by an inward-dipping ring fault system. The ring fault system consists in a 1-2 km wide fault zone that encircles an inner caldera region ~ 5 km in diameter and is often marked by the occurrence of pore fluids ascending through the fault zone, up to the seafloor, particularly in the western sector of the bay. A shallow magmatic intrusion along the ring fault zone was also detected offshore Bagnoli in the eastern part of the Pozzuoli Bay (Sacchi et al., 2014). Following the NYT eruption, the inner caldera region underwent significant deformation and resurgence with a maximum cumulative uplift of the offshore structure in the order of 180 m. The net uplift rate of the caldera resurgent dome was ~ 9 - 12 mm/year during the period 15.0 \u2013 6.6 ka BP. The style of deformation of the resurgent structure can be described in terms of a broad doming, accompanied by subordinate brittle deformation, mostly concentrated in a small apical graben at the summit of the resurgent dome (Cole et al., 2005). Chronostratigraphic calibration of seismic profiles obtained by three tephra layers cored in the Pozzuoli Bay indicates 5 to 25 m of post-Roman differential subsidence and tilting towards ESE of the inner caldera resurgence, as recorded by the drowning of the infralittoral prograding wedge below the present-day storm wave base

VOLCANICLASTIC DEPOSITION AND MIGRATION OF BASIN DEPOCENTRES AFTER THE ERUPTION OF THE NEAPOLITAN YELLOW TUFF: THE POZZUOLY BAY (NAPLES, ITALY)

The Campi Flegrei is an active caldera located on the coastal zone of SW Italy (Fig. 1), close to the town of Naples Bay, that has been characterized by explosive activity and unrest throughout the Late Quaternary. This area represents a very active segment of the Eastern Tyrrhenian margin and may be regarded as an ideal laboratory to understand the mechanisms of caldera dynamics and the interplay between volcanism, tectonics and sedimentary processes along a continental back-arc margin. Recent research at Campi Flegrei has shown that a significant part of the offshore volcaniclastic products and structures, the late-stage geodynamic evolution of the inner caldera resurgence and the stratal geometry of the caldera fill are still poorly known. Particularly, highresolution seismic data highlight the presence of an intra-caldera resurgent dome in the inner sector of the Pozzuoli bay that underwent significant uplift/subsidence after the eruption of the NYT (Sacchi et al., this volume). In this study we integrate geophysical data of different resolution/penetration obtained from high-resolution reflection seismic profiles (Chirp and Sparker sources) partly calibrated by gravity core in order to provide a 3D depositional model of density flows and migration of basin depocentres for the Pozzuoli Bay after the eruption of the NYT. The new data document the occurrence of two distinct layers of resediments, mostly represented by density flow deposits, separated by an interval of hemipelagic sediments. The two density flow units display a remarkable difference in their thickness and internal geometry. Across the bay, the lower unit is ca 5m thick in the western sector and reaches its maximum of ca 10 m in the central sector while it is absent towards the east. The upper unit, on the contrary, displays the minimum thickness of 10m close to the central sector of the bay and increases up to ca 16 and 12m in the western and eastern sector of the bay, respectively. The variation in thickness of the density flow deposits appears to be related with the amount of sediments available. The upper density flow deposits is also internally more chaotic respect to the lower one, suggesting higher energy and/or turbulence (Fig. 2). Sections and isopach maps clearly illustrate that the basin depocentre topography is not fixed at one position but migrates southwards in time (Fig. 3). Based on the above observations, we suggest that the uplift of the resurgent dome and subsidence of the southern sector, occurred after the eruption of the Neapolitan Yellow Tuff, acted as a major control in the increase of the sea-floor gradient in the Pozzuoli bay. This may have triggered in turn, the deposition of gravity flow deposits along with a progressive migration of basin depocentres through time

Architettura stratigrafica ed evoluzione del Golfo di Pozzuoli negli ultimi 15 ka:una nuova prospettiva sulla caldera del Tufo Giallo Napoletano,Campi Flegrei, margine tirrenico orientale.

I Campi Flegrei rappresentano un distretto vulcanico attivo che si sviluppa al confine tra il settore emerso e sommerso del margine continentale campano. Il distretto vulcanico occupa una superficie di circa 200 km2, è strutturalmente dominato da una caldera di collasso del diametro di circa 8 km formatasi in seguito all’eruzione del Tufo Giallo Napoletano (TGN), un deposito ignimbritico del volume di 30-50 km3 Dense Rock Equivalent, datato a 15 ka B.P. circa, ed è attivo da almeno 78 ka B.P circa. L’obiettivo di questo lavoro è di ricostruire l’architettura stratigrafica e l’evoluzione vulcanotettonica tardo-Quaternaria del sistema caldera di collasso - faglia anulare - risorgenza intra-calderica del settore sommerso della caldera del TGN. A tal fine è stata analizzata una fitta maglia di profili sismici a riflessione monocanale di alta (Sparker) ed altissima (Subbottom Chirp) risoluzione. I dati sismici sono stati successivamente integrati sia con quelli ottenuti dall’analisi di carotaggi a gravità e batimetrici multibeam che con quelli disponibili in letteratura e, nell’insieme, analizzati in ambiente GIS. I nuovi dati indicano che il settore interno dell’area collassata a seguito dell’eruzione del TGN evolve inizialmente in condizioni di mare basso. L’area intra-calderica viene successivamente interessata dalla formazione di una struttura antiforme (risorgenza intra-calderica) il cui tasso di sollevamento è stato comparabile con l’innalzamento eustatico nell’intervallo Pleistocene superiore – Olocene [Lambeck et al., 2011]. A circa 10 ka B.P. il settore centrale della struttura risorgente raggiunge l’esposizione subaerea (terrazzo morfologico de “La Starza”). La calibrazione dei profili sismici Chirp con markers tefro-stratigrafici riconosciuti in un carotaggio e datati al 1538 A.D., 79 A.D. indica l’instaurarsi di un periodo di subsidenza in epoca post-Romana, registrato dall’annegamento di 10-25 m del cuneo di progradazione infralittorale rispetto alle profondità di equilibrio funzionale attualmente segnalate in area Mediterranea. L’interpretazione sismostratigrafica rivela, inoltre, la presenza di fluidi che risalgono attraverso la zona di faglia anulare che delimita la caldera del TGN. Bibliografia Lambeck, K., Antonioli, F., Anzidei, M., Ferranti, L., Leoni, G., Scicchitano, G., Silenzi, S., (2011). Sea level change along the Italian coast during the holocene and projections for the future. Quaternary International, 232, 250-257

A difficult case of necrotizing fasciitis caused by Acinetobacter baumannii

This study reports the case of a 55-year-old woman with diabetes with a necrotizing fasciitis of the right lower limb and the perineum, first admitted at the emergency department for septic shock with cardiac arrest, and later transferred to the department of surgery. Microbiological and histopathological examination confirmed the diagnosis of necrotizing fasciitis caused by Acinetobacter baumannii. A broad-spectrum antibiotic therapy was administered and later readjusted according to the results of microbiological culture. Intensive hemodynamic support was required. Wounds were dressed daily with a 3 percent boric acid solution and a silver sulfadiazine-impregnated dressing. An extensive surgical debridement was promptly performed and repeated until complete control of the infection. Wounds were finally covered with split-thickness skin grafts. The infection was overcome 35 days after admission. The graft take was 100%. Postoperative rehabilitation was required because of the functional limitation of lower limb movements. Follow-up at 6 months showed no functional deficit and an acceptable aesthetic result. Necrotizing fasciitis is a life-threatening disorder, especially in patients with diabetes, whose clinical diagnosis may sometimes be challenging. Early recognition and treatment represent the most important factors influencing surviva

The Neapolitan Yellow Tuff caldera offshore the Campi Flegrei: Stratal architecture and kinematic reconstruction during the last 15 ky

In this study we integrate high-resolution swath bathymetry, single channel reflection seismic data and gravity core data, to provide new insights into the shallow structure and latest Quaternary to Holocene evolution of the submerged sector of the Neapolitan Yellow Tuff (NYT) caldera (Campi Flegrei) in the Pozzuoli Bay. The new data allow for a reconstruction of the offshore geometry of the NYT caldera collapse\u2013ring fault system, along with the style and timing of deformation of the inner caldera resurgence. Our interpretation shows that the NYT eruption (~15 ka BP) was associated with a caldera collapse bounded by an inward-dipping ring fault system. The ring fault system consists in a 1\u20132 km wide fault zone that encircles an inner caldera region ~5 km in diameter and is often marked by the occurrence of pore fluids ascending through the fault zone, up to the seafloor, particularly in the western sector of the bay. A shallow magmatic intrusion along the ring fault zone was also detected offshore Bagnoli in the eastern part of the Pozzuoli Bay. Following the NYT eruption, the inner caldera region underwent significant deformation and resurgence with a maximum cumulative uplift of the offshore structure in the order of 180 m. The net uplift rate of the caldera resurgent dome was ~9\u201312 mm/year during the period 15.0\u20136.6 ka BP. The style of deformation of the resurgent structure can be described in terms of a broad doming, accompanied by subordinate brittle deformation, mostly concentrated in a small apical graben at the summit of the resurgent dome. Chronostratigraphic calibration of seismic profiles obtained by three tephra layers cored in the Pozzuoli Bay indicates 5 to 25 m of post-Roman differential subsidence and tilting towards ESE of the inner caldera resurgence, as recorded by the drowning of the infralittoral prograding wedge below the present-day storm wave base

Spectral analysis of lava flows: Temporal and physicochemical effects

In a volcanic context, the spectral response of lava flows depends on several endogenous and exogenous factors, like chemical composition, passing of years and weathering. A deeper knowledge about lava properties can be inferred by investigating their spectral response in satellite images. Here, we compare the spectral response of lava in time, physical, and chemical characteristics, inspecting visible to infrared high spatial resolution ESA Sentinel-2 satellite images of different volcanoes. Our results show increasing and decreasing patterns of the lava spectral response as a function of time and physicochemical composition

Charge Collection Dynamics of the ARCADIA Passive Pixel Arrays: Laser Characterization and TCAD Modeling

Monolithic Active Pixel Sensors (MAPS) represent one of the most promising technologies for the next generation of radiation detectors. The ARCADIA project aims at the development of Fully Depleted (FD) MAPS employing a production process compatible with a 110 nm commercial CMOS technology. The first engineering run of the project included matrices of active pixels with embedded analog and digital frontend electronics and passive test structures such as passive pixel arrays, MOS capacitors and backside diodes. Although the produced samples were already characterized from the electrical point of view, a thorough study of the charge collection dynamics of the passive pixel arrays was still missing. In this paper we show the results of the dynamic characterization of a group of passive pixel arrays with different pixel pitches (50, 25 and 10 μm) and different pixel layouts. The tested samples have been illuminated from the backside with an infrared and a red laser with wavelengths equal to 1,060 nm and 660 nm, respectively. The pixel arrays have been mounted on a custom readout PCB connected to an external amplifier with 1 GHz bandwidth and the signals have been acquired through a fast digital oscilloscope. We employed both focused and unfocused laser spots to evaluate the change in the measured signal as a function of the laser spot position and the average response of the pixel arrays. An excellent agreement has been demonstrated by comparing the measured signals with the results of transient TCAD simulations and a time for 50% charge collection of 7.8, 4.2 and 2.6 ns has been predicted and experimentally validated in pixels with 50, 25 and 10 μm pitch, respectively

An Integrated Multiscale Method for the Characterisation of Active Faults in Offshore Areas. The Case of Sant\u2019Eufemia Gulf (Offshore Calabria, Italy)

Diagnostic morphological features (e.g., rectilinear seafloor scarps) and lateral offsets of the Upper Quaternary deposits are used to infer active faults in offshore areas. Although they deform a significant seafloor region, the active faults are not necessarily capable of producing large earthquakes as they correspond to shallow structures formed in response to local stresses. We present a multiscale approach to reconstruct the structural pattern in offshore areas and distinguish between shallow, non-seismogenic, active faults, and deep blind faults, potentially associated with large seismic moment release. The approach is based on the interpretation of marine seismic reflection data and quantitative morphometric analysis of multibeam bathymetry, and tested on the Sant\u2019Eufemia Gulf (southeastern Tyrrhenian Sea). Data highlights the occurrence of three major tectonic events since the Late Miocene. The first extensional or transtensional phase occurred during the Late Miocene. Since the Early Pliocene, a right-lateral transpressional tectonic event caused the positive inversion of deep (>3 km) tectonic features, and the formation of NE-SW faults in the central sector of the gulf. Also, NNE-SSW to NE-SW trending anticlines (e.g., Maida Ridge) developed in the eastern part of the area. Since the Early Pleistocene (Calabrian), shallow (<1.5 km) NNE-SSW oriented structures formed in a left-lateral transtensional regime. The new results integrated with previous literature indicates that the Late Miocene to Recent transpressional/transtensional structures developed in an 3cE-W oriented main displacement zone that extends from the Sant\u2019Eufemia Gulf to the Squillace Basin (Ionian offshore), and likely represents the upper plate response to a tear fault of the lower plate. The quantitative morphometric analysis of the study area and the bathymetric analysis of the Angitola Canyon indicate that NNE-SSW to NE-SW trending anticlines were negatively reactivated during the last tectonic phase. We also suggest that the deep structure below the Maida Ridge may correspond to the seismogenic source of the large magnitude earthquake that struck the western Calabrian region in 1905. The multiscale approach contributes to understanding the tectonic imprint of active faults from different hierarchical orders and the geometry of seismogenic faults developed in a lithospheric strike-slip zone orthogonal to the Calabrian Arc