953 research outputs found
The submerged structure and stratal architecture of the Neapolitan Yellow Tuff (NYT) caldera, offshore the Campi Flegrei, (Eastern Tyrrhenian Margin): new insights from high resolution seismics and gravity core data
No full textThe Campi Flegrei is an active volcanic area defined by a
quasi-circular depression that covers some 200 km2 of the coastal
zone of SW Italy, a large part of which develops off the Naples
(Pozzuoli) Bay (Fig. 1). The area has been active at least since 60
ka BP ( Pappalardo et al., 1999), and is structurally dominated by a
caldera, 6 km in diameter, associated with the eruption of the
Neapolitan Yellow Tuff (NYT), a 40 km3 Dense Rock Equivalent
(DRE) ignimbrite (Scarpati et al., 1993) dated at ca 15 ka BP
(Deino et al., 2004), that covered the district now occupied by the
city of Naples, the Campi Flegrei and a large area of the
continental shelf off the Pozzuoli Bay.
The volcanological evolution of the NYT caldera as been long
described on the basis of outcrop and subsurface studies onland
(Rosi & Sbrana, 1987; Orsi et al., 1996, 2004 and references
therein; Di Vito et al., 1999; Perrotta et al., 2006; Fedele et al.,
2011), but its offshore morphology, detailed structure and recent
stratigraphic setting are still poorly understood.
In this study we integrate geological and geophysical data of
different resolution/penetration obtained from high-resolution
reflection seismic profiles (Sparker and Chirp source) with gravity
core and swath bathymetry to better constrain the shallow
structure, stratigraphic architecture and latest Quaternary to
Holocene evolution of the submerged sector of the NYT caldera
off the Pozzuoli Bay.
Our data clearly image, for the first time, the offshore geometry
of the NYT caldera ring-fault zone, as well as the style and timing
of volcano-tectonic deformation associated with the late stage
evolution of the NYT inner caldera resurgence. Our interpretation
suggests that since 15 ka the offshore sector of NYT inner caldera
underwent significant deformation and uplift (with minor
subsidence episodes) that occurred at almost the same rate as the
post-glacial sea-level rise. Particularly, the inner Pozzuoli Bay
started to deform soon after 15 ka BP, when sea-level rise was
initially faster than uplift. This caused a general increase of the
accommodation space that was progressively filled up by
volcaniclastic sediments. Since ca. 8 ka BP, along with the mid
Holocene decrease in the rate of the sea-level rise, the early NYT
resurgent structure was then uplifted up to the sea-level or even to
partial subaerial exposure. From ca. 8 to 5 ka BP two distinct
layers of volcaniclastic resediments, mostly represented by gravity
flow deposits, formed throughout the Bay. A significant post-
Roman (post 2 ka BP) subsidence phase of ca 10 m is then
recorded offshore Pozzuoli by the drowning of the infralittoral
prograding wedge below the present-day fair-weather wave base.
REFERENCES
Deino AL, Orsi G, de Vita S, Piochi M (2004) The age of the Neapolitan Yellow
Tuff caldera-forming eruption (Campi Flegrei caldera—Italy) assessed by
40Ar/39Ar dating method. J. Volcanol. Geotherm. Res. 133, 157–170.
Di Vito M., Isaia R., Orsi G., Southon J., de Vita S., D’Antonio M., Pappalardo
L., Piochi M., 1999. Volcanism and deformation since 12,000 years at the
Campi Flegrei caldera (Italy), J. Volcanol. Geotherm. Res. 91 (2-4), 221-246.
Fedele L., Insinga D.D., Calvert A.T., Morra V., Perrotta A., Scarpati C., 2011.
40Ar/39Ar dating of tuff vents in the Campi Flegrei caldera (southern Italy):
toward a new chronostratigraphic reconstruction of the Holocene volcanic
activity. Bull. Volcanol. 73, 1323-1336.
Orsi G, de Vita S, Di Vito M, 1996. The restless, resurgent Campi Flegrei nested
caldera (Italy): constraints on its evolution and configuration. J. Volcanol.
Geotherm. Res. 74, 179–214.
Orsi G., Di Vito M.A. Isaia R., 2004. Volcanic hazard assessment at the restless
Campi Flegrei caldera. Bull. Volcanol. 66, 514–530.
Pappalardo L., Civetta L., D’Antonio M., Deino A., Di Vito M., Orsi G.,
Carandente A., de Vita S., Isaia R. & Piochi M., 1999. Chemical and Srisotopical
evolution of the Phlegrean magmatic system before the Campanian
Ignimbrite and the Neapolitan Yellow Tuff eruptions J. Volcanol. Geotherm.
Res. 91, 141-166.
Perrotta A., Scarpati C., Luongo G., Morra V., 2006. The Campi Flegrei caldera
boundary in the city of Naples. In: De Vivo B (ed) Volcanism in the
Campania Plain: Vesuvius, Campi Flegrei and Ignimbrites. Elsevier,
Amsterdam, pp 85–96 (in the series Developments in Volcanology, 9)
Scarpati C., Cole P., & Perrotta A., 1993. The Neapolitan Yellow Tuff- A large
volume multiphase eruption from Campi Flegrei, Southern Italy. Bull.
Volcan. 55, 343-35
Large earthquakes along slow converging plate margins: Calabrian Arc paleoseismicity based on the submarine turbidite record
No full textThe Calabrian Arc subduction-rollback system hosts seismogenic faults capable of generating earth-
quakes exceeding magnitude 7. Since earthquakes are the result of long-term geodynamic processes, doc-
umenting seismic activity during a sufficiently long time interval is of fundamental importance for
hazard scenarios. Instrumental and historical data provide critical information on seismogenesis, but they
cover time periods shorter than the recurrence times of large earthquakes, especially in areas with low
deformation rates such as Calabria. If onshore paleoseismological studies are fundamental to compile
earthquake catalogs, they are sometime affected by the relatively poor continuity of sedimentation in
the subaerial environment.
In this study we applied the paleoseismological approach to the submarine environment to reconstruct
the record of high-energy sedimentary events triggered by seismic activity. We analyzed three gravity
cores collected in disconnected sedimentary basins to reconstruct resedimentation processes during
the Holocene, integrating inland information for a better assessment of tectonic activity and seismogen-
esis. Multiproxy analyses of the sedimentary record constrained by radiometric dating allowed recon-
structing event stratigraphy and linking resedimented deposits to specific earthquakes.
Onshore and offshore data allow to identify large-magnitude earthquakes in the central Calabrian Arc
subduction system during the Holocene, with inferred epicenters located either along normal faults
onshore and/or related to the slab dynamics. The turbidite record reveals 20 major events during the last
10 ka, with sources including crustal faults in Calabria (i.e. Lakes, Rossano and Cittanova faults). Analyses
of sediment samples and high-resolution seismic reflection images allowed identification of different
types of resedimented deposits during the last 30–50 ka. The basin-wide occurrence of three megatur-
bidites/homogenites suggests they are related to megatsunamis sourced by far field earthquakes along
the Hellenic Arc. Megaturbidites with a more limited spatial extent are interpreted as subduction-type
events in the Calabrian Arc, while thinner seismo-turbidites record the activity of crustal structures
including faults onshore. Results suggest a recurrence time of 2–3 ka for major Calabrian Arc events that
needs to be considered for a reliable hazard assessment in the Mediterranean region
The proximal marine record of the Marsili Seamount in the last 7ka (Southern Tyrrhenian Sea, Italy): Implications for the active processes in the Tyrrhenian Sea back-arc
No full textThe volcanism of back-arc basins resembles that of oceanic spreading centers, rifts, and, in vanishing stages, extensional arcs, depending on the amount and rate of the dynamic processes associated to the subduction. Marsili Seamount (MS) represents the axial ridge of the Southern Tyrrhenian Sea back-arc basin, which is connected to the slab roll-backing processes affecting the Calabrian Arc (Italy). The Southern Tyrrhenian Sea back-arc is characterized by a significant decline in the spreading rate with time (2.8-3.1. mm/a to less than 1.8. mm/a in the last 0.78-1. Ma). MS develops between about 1. Ma and 3. ka and mainly consists of lava flows erupted from central and fissural vents. The MS products belong to the calcalkaline association and range in composition from basalts to trachytes. We present new stratigraphic, geochronological, and geochemical data (glass shards and minerals) of tephra from a 2.35. m long gravity core (Marsili1 core) recovered on MS at 943. m b.s.l. We recognize five tephras [M1 (top of the core) to M5 (bottom)] represented by poorly to highly vesiculated ashes. The lowermost tephra M5 emplaced between ca. 7 and 26. ka B.P.; it represents the less evolved distal counterpart of the Unit D related to the Biancavilla-Montalto products of Mount Etna (Sicily). The M1 to M4 tephras emplaced between 2.1 and 7.2. ka B.P. and are related to strombolian-like submarine eruptions of NNE-SSW aligned MS vents. The composition of the M1-M4 glasses ranges from basaltic trachyandesites to andesites and trachytes. The M1 to M4 magmas mainly originated by crystal fractionation from a heterogeneous mantle source with varying LILE enrichments by subduction-related fluids. The degree of evolution of the MS magmas increases with decreasing time. The formation of vertically stacked magma storage zones at the crust/mantle interface and within MS is related to the vanishing Southern Tyrrhenian Sea opening, which implies the rapid (<. 1. Ma) evolution from a slow spreading back-arc setting to an arc system
The turbulent dissipation rate from PIV measurements
No full textThe result of a particle-image velocimetry (PIV) measurement is a velocity field averaged over interrogation windows. This severely affects the measurement of small-scale turbulence quantities when the interrogation window size is much larger than the smallest length scale in turbulence. A direct measurement of the dissipation rate demands the measurement of gradients of the velocity field, which are now underestimated because the small-scale motion is not resolved. A popular procedure is to relate the statistical properties of the measured, but underresolved gradients to those of the true ones, invoking a large-eddy argument [3]. We show that the used proportionality constant, the Smagorinsky constant, should depend on the window overlap, on the used elements of the strain tensor, and on the way in which derivatives are approximate
How the dispersion of a droplet cloud depends on its initial size
No full textA cloud of droplets evolves under the influence of strong turbulence. The droplets are made from a phosphorescent fluid. From this cloud we select at t = 0 a narrow line by exciting the droplets with a UV laser, which causes them to glow for a few milliseconds. The dispersion of this line is followed in time using a fast intensified camera. A large range of droplet sizes (Stokes number St) was measured. It appears that lines with St \approx 1 disperse faster than a line of fluid tracers. Lines of droplets which are narrowest initially, spread fastest
Reverend William M. Paden, D.D.
No full textThis photograph is a portrait, featured in a publication, of Reverend William M. Paden, D.D. He is wearing a dark suit, light shirt, and a dark tie with polka dots. His hair is parted in the middle and he wears a mustache. He is also wearing wire-rimmed glasses. The background is a medium gray shade.The photograph is in good condition, except for a slight wrinkle in the bottom right corner. On the back the paper appears torn because of glue and there is a small pink spot in the bottom half of the photograph. The following text is printed at the bottom of the photograph: "Reverend William M. Paden D.D. Beloved, purposeful, Missioner of Good Cheer. Leader of Presbyterianism in Utah for thirty-four years, as Pastor, Executive, Author and Counselor. Together by the grace of God, we enter the forward-looking years, growing ever richer in Christian faith and service." The Archives, Giovale Library, Westminster College, has a collection of materials authored by William Paden and also materials about him. Additional biographic information about Dr Paden is available in: Brackenridge, R. Douglas. Westminster College of Salt Lake City. Logan, Utah: Utah State University Press, 1998, pp. 118, 121, 124, 140
On fully nonlinear CR invariant equations on the Heisenberg group
No full textAbstractIn this paper we provide a characterization of second order fully nonlinear CR invariant equations on the Heisenberg group, which is the analogue in the CR setting of the result proved in the Euclidean setting by A. Li and the first author in Li and Li (2003) [21]. We also prove a comparison principle for solutions of second order fully nonlinear CR invariant equations defined on bounded domains of the Heisenberg group and a comparison principle for solutions of a family of second order fully nonlinear equations on a punctured ball
OBILJEŽJA POSLOVANJA HOTELSKE GRUPACIJE VALAMAR RIVIERA D.D.
No full textU teorijskom dijelu rada se govori o oblicima hotelskih lanaca, njihovom načinu povezivanja, prednostima i nedostatcima hotelskih grupacija te se opisuju i grafički prikazuju vodeći hotelski lanci u Republici Hrvatskoj i svijetu. U praktičnom dijelu rada se analizira hotelska grupacija Valamar Riviera d.d. Ukratko se navode opće informacije o grupaciji te opisuje povijest kompanije. Pobliže se prikazuje i opisuje portfelj kompanije kao i njezine vrijednosti, govori se o društveno odgovornom poslovanju te o prodaji i kvaliteti grupacije. Navode se i obrađuju brendovi koji spadaju pod grupaciju. Pomoću primjera Dubrovnik President Hotela i Istra Premium Camping Resorta detaljno je analizirano i prikazano poslovanje hotelske grupacije Valamar Rivierra d.d. Također je prikazana i SWOT analiza hotelske grupacije Valamar Riviera d.d.In the theoretical part of this final paper the focus is on introducing different types of hotel chains, the way those businesses are formed and merged, and the main characteristics including advantages and flaws of such formations within the hotel industry. Additionally, the list of the main hotel chains in Croatia is provided, supplemented by photos. In the practical part, the author delves into the main focus of the thesis - hotel chain Valamar Riviera d.d. The company is described at length, and the history of the hotel chain is provided. The company's portfolio and its value is examined, and Valamar's sales figure and quality promise are listed. The company's social responsibility and promise is presented. Valamar also has multiple brands under its umbrella, all of which are analysed. In the final chapters, two brands are described at length - President Hotel and Istria Premium Camping Resort. Finally, a SWOT analysis of the hotel group is carried out
The Potentials of Recommender Systems Challenges for Student Learning
No full textIncreasingly, educators make use of learning-by-doing approaches to teach students
of STEM programmes the skills that they need to become successful in
careers in research and development. However, we argue that the technical
challenges addressed in these programmes are often too limited and therefore
do not support the students in gaining the more advanced skill sets required to
thrive in our technology-oriented economy. We therefore suggest to incorporate
realistic and complex challenges that model real-world problems faced in
industrial settings. Focusing on the domain of recommender systems, we see
potentials in embedding recommender systems challenges to enhance student
learning to teach students the skills required by modern data scientists
The Neapolitan Yellow Tuff caldera offshore the Campi Flegrei: Stratal architecture and kinematic reconstruction during the last 15 ky
No full textIn 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–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.
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 15.0–6.6 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.
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
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