Assessing the volcanic hazard for Rome. 40Ar/39Ar and In-SAR constraints on the most recent eruptive activity and present-day uplift at Colli Albani Volcanic District

We present new 40Ar/39Ar data which allow us to refine the recurrence time for the most recent eruptive activity occurred at Colli Albani Volcanic District (CAVD) and constrain its geographic area. Time elapsed since the last eruption (36 kyr) overruns the recurrence time (31 kyr) in the last 100 kyr. New interferometric synthetic aperture radar data, covering the years 1993–2010, reveal ongoing inflation with maximum uplift rates (>2 mm/yr) in the area hosting the most recent (<200 ka) vents, suggesting that the observed uplift might be caused by magma injection within the youngest plumbing system. Finally, we frame the present deformation within the structural pattern of the area of Rome, characterized by 50 m of regional uplift since 200 ka and by geologic evidence for a recent (<2000 years) switch of the local stress-field, highlighting that the precursors of a new phase of volcanic activity are likely occurring at the CAVD

The late MIS 5 Mediterranean tephra markers: A reappraisal from peninsular Italy terrestrial records

We present new tephrostratigraphic records from the late MIS 5 (ca 110e80 ka) terrestrial sediments from southern and central Italy. On the one hand, the central Italy record consists of an outcropping lacustrine sequence from the Sulmona intermountain basin that contains four trachyticephonolitic tephra layers (POP3, POP2a, POP2b, POP1), all of which show a K-alkaline affinity that is typical for the Roman co-magmatic Province. The POP3 and POP1 layers were dated by 40Ar/39Ar method at 106.2 1.3 ka (2s) and 92.4 4.6 ka (2s), respectively. The sequence in southern Italy, on the other hand, is represented by post-Tyrrhenian coastal deposits of the Cilento area, Campania, which contain two trachytic layers (CIL2, CIL1) that show the same K-alkaline affinity. Based on their chemical compositions and radiometric ages, POP3 and POP1 are firmly correlated with the marine tephra layers X-5 (105 2 ka) and C-22 (ca 90 ka), which, in turn, match tephras TM-25 and TM-23-11, respectively, in the lacustrine sequence of Lago Grande di Monticchio (southern Italy). Of note, the POP1 layer also matches the Adriatic Sea tephra PRAD 2517 that was previously correlated with the older X-5 layer. The tephra couplet POP2a and POP2b (ca 103 and 103.5 ka, extrapolated ages) are compatible with the TM- 24b and TM-24-3 tephras in Monticchio, which match both the stratigraphic positions and the chemical compositions. In the Cilento area, as well as the already described X-6 layer (ca 108 ka) (CIL2), we recognise a new stratigraphic superimposed layer (CIL1) that matches the POP3/TM-25/C-27/X-5 Mediterranean marker(s). In summary, the data presented here provide new chemical and 40Ar/39Ar chronological constraints towards a robust late MIS 5 tephrostratigraphy of the central Mediterranean, although at the same time, they also reveal how the tephrostratigraphy itself might be flawed when dealing with tephra markers that are not adequately constrained and characterised.Published31-451V. Storia eruttivaJCR Journa

The Volsci Volcanic Field (central Italy). Eruptive history, magma system and implications on continental subduction processes.

Here, we report on the Quaternary Volsci Volcanic Field (VVF, central Italy). In light of new 40Ar/39Ar geochronological data and compositional characterization of juvenile eruptive products, we refine the history of VVF activity, and outline the implications on the pre-eruptive magma system and the continental subduction processes involved. Different from the nearby volcanic districts of the Roman and Campanian Provinces, the VVF was characterized by small-volume (0.01–0.1 km3) eruptions from a network of monogenetic centers (mostly tuff rings and scoria cones, with subordinate lava occurrences), clustered along high-angle faults of lithospheric depth. Leucite-bearing, high-K (HKS) magmas (for which we report for the first time the phlogopite phenocryst compositions) mostly fed the early phase of activity (∼761–539 ka), then primitive, plagioclase-bearing (KS) magmas appeared during the climactic phase (∼424–349 ka), partially overlapping with HKS ones, and then prevailed during the late phase of activity (∼300–231 ka). The fast ascent of primitive magma batches is typical of a tectonically controlled volcanic field, where the very low magma flux is a passive byproduct of regional tectonic strain. We suggest that the dominant compressive stress field acting at depth was accompanied by an extensional regime in the upper crust, associated with the gravity spreading of the Apennine chain, allowing the fast ascent of magma from the mantle source with limited stationing in shallow reservoirs

Physical stratigraphy and geotechnical properties controlling the local seismic response in explosive volcanic settings: the Stracciacappa maar (central Italy)

Nowadays, policies addressed to prevention and mitigation of seismic risk need a consolidated methodology finalised to the assessment of local seismic response in explosive volcanic settings. The quantitative reconstruction of the subsoil model provides a key instrument to understand how the geometry and the internal architecture of outcropping and buried geological units have influence on the propagation of seismic waves. On this regard, we present a multidisciplinary approach in the test area of the Stracciacappa maar (Sabatini Volcanic District, central Italy), with the aim to reconstruct its physical stratigraphy and to discuss how subsoil heterogeneities control the 1D and 2D local seismic response in such a volcanic setting. We first introduce a new multidisciplinary dataset, including geological (fieldwork and log from a 45-m-thick continuous coring borehole), geophysical (electrical resistivity tomographies, single station noise measurements, and 2D passive seismic arrays), and geotechnical (simple shear tests performed on undisturbed samples) approaches. Then, we reconstruct the subsoil model for the Stracciacappa maar in terms of vertical setting and distribution of its mechanical lithotypes, which we investigate for 1D and 2D finite element site response analyses through the application of two different seismic scenarios: a volcanic event and a tectonic event. The numerical modelling documents a significant ground motion amplification (in the 1–1.5 Hz range) revealed for both seismic scenarios, with a maximum within the centre of the maar. The ground motion amplification is related to both 1D and 2D phenomena including lithological heterogeneity within the upper part of the maar section and interaction of direct S-waves with Rayleigh waves generated at edges of the most superficial lithotypes. Finally, we use these insights to associate the expected distribution of ground motion amplification with the physical stratigraphy of an explosive volcanic setting, with insights for seismic microzonation studies and local seismic response assessment in populated environments

THE ITALIAN QUATERNARY VOLCANISM

The peninsular and insular Italy are punctuated by Quaternary volcanoes and their rocks constitute an important aliquot of the Italian Quaternary sedimentary successions. Also away from volcanoes themselves, volcanic ash layers are a common and frequent feature of the Quaternary records, which provide us with potential relevant stratigraphic and chronological markers at service of a wide array of the Quaternary science issues. In this paper, a broad representation of the Italian volcano-logical community has joined to provide an updated comprehensive state of art of the Italian Quaternary volcanism. The eruptive history, style and dynamics and, in some cases, the hazard assessment of about thirty Quaternary volcanoes, from the north-ernmost Mt. Amiata, in Tuscany, to the southernmost Pantelleria and Linosa, in Sicily Channel, are here reviewed in the light of the substantial improving of the methodological approaches and the overall knowledge achieved in the last decades in the vol-canological field study. We hope that the present review can represent a useful and agile document summarising the knowledege on the Italian volcanism at the service of the Quaternary community operating in central Mediterranean area

Pleistocene tephrostratigraphy and palaeoclimatology in the central Mediterranean region: ongoing research in Fucino Basin (central Apennines, Italy)

Palaeoclimatic records spanning beyond the radiocarbon range generally derive their chronologies from orbital tuning strategies. These chronologies can introduce a priori assumptions that are difficult to test and, possibly, circular arguments in palaeoclimatic reconstructions. We elaborate two high-resolution, multi-proxy and tephrochronologically-constrained records (F1-F3 and F4-F5) of past environmental and climatic changes in the central Mediterranean region. We perform geochemical (X-ray fluorescence scanning, carbon, nitrogen and sulphur elemental analysis through combustion), isotopic (C and O stable isotope mass spectrometry on bulk carbonates and organic matter), mineralogical (X-ray powder diffraction) and grain-size analyses on lacustrine marls recovered from palaeolake Fucino (Abruzzo, central Italy). Lacustrine sediments were acquired during two scientific drilling campaigns (F1-F3 and F4-F5) interesting the first ca. 85 m of the 1 km-thick and 2 Ma-old Fucino sedimentary succession. We make use of detailed tephrostratigraphic and tephrochronological frameworks to produce robust and independent chronologies based on new and published 40Ar/39Ar and 14C dating of tephra layers. On the basis of our chronologies, the F1-F3 and F4-F5 records continuously span over the last two glacial-interglacial cycles and over the last five glacial-interglacial cycles, respectively. We combine our geological data into proxies for catchment- and regional-scale environmental processes. Our proxy time-series depict prominent orbital and sub-orbital environmental changes that can be tracked in other lacustrine, marine and speleothem records across the Mediterranean and North Atlantic regions. Thanks to tephrostratigraphic correlations and chronological matching, we produce spatially coherent palaeoclimatic reconstructions recognising a complex interplay between regional environmental processes and broad-scale climatic events. We highlight strong orbital forcing for past climate changes

alpha-spectroscopy studies of the new nuclides Pt-165 and Hg-170

The new nuclides 165Pt and 170Hg were produced in the reactions 92Mo(78Kr,5n) and 96Ru(78Kr,4n) at bombarding energies of 418 MeV and 390 MeV, respectively. For 170Hg an α-particle energy of Eα=7590(30)keV and half-life of t1/2=0.08+0.40−0.04ms were deduced, while for 165Pt the corresponding values were 7272(14) keV and 0.26+0.26−0.09ms. Comparison of the reduced α-decay widths with systematics indicates that both α decays are unhindered. Although combining the measured α-decay Q values with extrapolated masses suggests that both new nuclides are unbound to two-proton emission by more than 1 MeV, their α-decay half-lives are too short for this decay mode to compete. Improved data were also obtained for 166,167Pt, produced via the 96Ru(78Kr,α4n) and 96Ru(78Kr,α3n) reactions at bombarding energies of 390 MeV and 418 MeV.peerReviewe