Università di Pisa

Identifying the hydrological and environmental response of the European Alpine region to different combinations of climate boundary conditions is crucial to advance the reliability of predictive climate models and thus shape climate adaptation policies that will impact millions of people in seven countries. Here we present a high-resolution multiproxy speleothem record (stable oxygen and carbon isotope ratios, petrography and magnetic properties) from Rio Martino Cave (Piedmont, Southern Alps, Italy), which covers the first part of the Penultimate Glacial (early MIS 6, 182e157 ka). During early MIS 6, the combination of high climatic precession and obliquity amplified the peak in Northern Hemisphere (NH) summer insolation intensity at ca. 174 ka to almost interglacial levels, leading to northward migration of the Intertropical Convergence Zone and the enhancement of the boreal monsoon system. At orbital scale, the hydroclimatic record from Rio Martino closely follows the precession pattern, and shows a wet interstadial phase between 180 and 170 ka, peaking at the precession minimum, characterized by glacial retreat and by the likely development of soils and vegetation up to 1900e2000 m a.s.l. in this alpine sector. This phase can be traced across the Southern Alps, and corresponds to pluvial conditions inferred from Western Mediterranean records, and to the interval of deposition of the cold Sapropel S6 in the eastern Mediterranean. We suggest that the interaction between an intensified northwesterly cold flow (relating to increased ice volume under glacial conditions), and the relatively warm waters of the NW Mediterranean (due to the peculiar atmospheric configuration occurring at the precession minimum) strongly enhanced the autumn cyclogenesis in the Northern Tyrrhenian Sea, fuelling intense precipitation to reach the Southern Alps. The Rio Martino record also shows a prominent sub-orbital variability, the overall structure of which is coherent with hemispheric changes in climate driven by cyclic perturbations of North Atlantic conditions related to the operation of the bipolar seesaw.

The Einstein Telescope (ET) is a proposed next-generation, underground gravitational-wave detector to be based in Europe. It will provide about an order of magnitude sensitivity increase with respect to the currently operating detectors and, also extend the observation band targeting frequencies as low as 3 Hz. One of the first decisions that needs to be made is about the future ET site following an in-depth site characterization. Site evaluation and selection is a complicated process, which takes into account science, financial, political, and socio-economic criteria. In this paper, we provide an overview of the site-selection criteria for ET, provide a formalism to evaluate the direct impact of environmental noise on ET sensitivity, and outline the necessary elements of a site-characterization campaign.

The temporal evolution of effusion rate is the main controlling factor of lava spreading and emplacement conditions. Therefore, it represents the most relevant parameter for characterizing the dynamics of effusive eruptions and thus for assessing the volcanic hazard associated with this type of volcanism. Since the effusion rate curves can provide important insights into the properties of the magma feeding system, several efforts have been performed for their classification and interpretation. Here, a recently published numerical model is employed for studying the effects of magma source and feeding dike properties on the main characteristics (e.g., duration, erupted mass, and effusion rate trend) of small‐volume effusive eruptions, in the absence of syn‐eruptive magma injection from deeper storages. We show that the total erupted mass is mainly controlled by magma reservoir conditions (i.e., dimensions and overpressure) prior to the eruption, whereas conduit processes along with reservoir properties can significantly affect mean effusion rate, and thus, they dramatically influence eruption duration. Simulations reproduce a wide variety of effusion rate trends, whose occurrence is controlled by the complex competition between conduit enlargement and overpressure decrease due to magma withdrawal. These effusion rate curves were classified in four groups, which were associated with the different types described in the literature. Results agree with the traditional explanation of effusion rate curves and provide new insights for interpreting them, highlighting the importance of magma reservoir size, initial overpressure, and initial width of the feeding dike in controlling the nature of the resulting effusion rate curve.

The timing of the Holocene volcanic activity of Tenerife (Canary Islands) is poorly constrained and the volcano- logical framework for this area is still incomplete. Most of the eruptions are dated only by a single 14C dating, or the ages are simply stratigraphically determined. We apply palaeomagnetism, increasingly used in the last years to date Holocene volcanism, to improve the knowledge of Tenerife volcanic history. We report on the palaeomagnetic dating, using the SHA.DIF.14K global model, of nine Holocene eruptions that produced scoria cones and major lava flows, and we compare our results with those previously obtained by 14C method. Four of the studied eruptions were previously dated by 14C, four were stratigraphically constrained, and one was never dated so far. Concerning the first group, for Boca Cangrejo and Mña Reventada eruptions, palaeomagnetic and 14C ages agree, while for the others we obtained older or younger ages than radiocarbon data. For the second group, one or more age ranges smaller than stratigraphic intervals were found. Finally, we provided the first dat- ing (790–723 BCE) of the Mña Grande eruption. We confirm that palaeomagnetism can be considered an excel- lent complement to the radiocarbon method, because it is applicable on volcanics with nearly all compositions and provides higher resolution dating, at least where reliable geomagnetic reference curves are available. The im- proved framework of the Holocene volcanic activity of Tenerife shows alternating periods characterized by low and high eruptive frequencies, with the last 3 kyr characterized by high eruptive frequency and dominated by ba- saltic eruptions.

Vulcano is one of the 7 volcanic islands and 6 seamounts forming the Aeolian volcanic district (Italy). Vulcano has a long eruptive record, and its last eruption (1888–90 AD) originated the definition of the Vulcanian eruptive style. Like most volcanic islands, Vulcano generates many potentially interconnected hazards, determining a potentially high risk. Here, we review the state of knowledge on its geology, eruptive activity, historical accounts, structural setting, geophysical and geochemical surveillance, and available hazard assessment, in order to have an updated picture of the state knowledge on volcanic hazard. We follow a prototypal reviewing scheme, based on three standardized steps: i) review of the volcanic system; ii) review of available eruptive and noneruptive hazard quantifications; iii) development of a conceptual interpretative model. We find that, while a rather vast literature is dedicated to the volcanic system of Vulcano and the reconstruction of past events, few quantitative hazard assessments exist. In addition, the range of natural variability considered for each hazard is potentially underestimated (e.g. limited range of considered eruption magnitude and style and of vent position), as it is the potential effect of multi-hazard impact. The developed conceptual model for the feeding system provides a synthetic picture of the present knowledge about the system, as emerged from the review. In addition, it allows for the identification of potential paths-to-eruption and provides a first order link among the main hazards. This review provides an up-to-date snapshot of existing knowledge on volcanic hazard at Vulcano on which to build future hazard quantifications as well as to support present and future decision making.

This paper describes the preliminary results of seismic survey performed in the area of Sos­Enattos mine (Lula, NU), by installing a linear array consisting of five short­term mobile stations. The aim was to acquire both environmental seismic noise signals and signals from an active seismic source generated by the blast of explosive charges placed inside the mine. The spectral analyses of seismic noise highlight the presence of a dominant low­frequency peak due to the marine microsism. A propagation velocity of P waves equal to 4500 m/s was estimated by analyzing the first arrivals of the seismic signal deriving from the explosion. Finally, using techniques of analysis of the local seismic response it was possible to obtain preliminary indications on the structure of the subsoil.

In this paper, we study the motion of a fluid with several dispersed particles whose concentration is very small (smaller than 10-3), with possible applications to problems coming from geophysics, meteorology, and oceanography. We consider a very dilute suspension of heavy particles in a quasi-incompressible fluid (low Mach number). In our case, the Stokes number is small and—as pointed out in the theory of multiphase turbulence—we can use an Eulerian model instead of a Lagrangian one. The assumption of low concentration allows us to disregard particle–particle interactions, but we take into account the effect of particles on the fluid (two-way coupling). In this way, we can study the physical effect of particles’ inertia (and not only passive tracers), with a model similar to the Boussinesq equations. The resulting model is used in both direct numerical simulations and large eddy simulations of a dam-break (lock-exchange) problem, which is a well-known academic test case. © 2014, Springer Basel.

In the frame of the ANtarctic DRILLing Program, volcanic glass fragments were collected from the AND-2A core between ~354 and 765 m below sea floor (mbsf) as accumulations (5–70 vol.%) within sediments. Here, we present the physical characteristics, age and geochemistry of the glass, which enable us to reconstruct Early to Middle Miocene volcanic activity in southern McMurdo Sound and, for the first time, document the response of volcanism to climate change in Antarctica. Glass-rich sediments include muddy-to-fine sandstone and stratified diamictite. Glass varies in color, size, vesicularity, crystal content, angularity, and degree of alteration. The mostly fresh glass exhibits delicate cuspate forms indicating deposition as primary ash fall. 40Ar–39Ar age determinations on individual glass grains are in good agreement with the depositional age model of the sediments (ca. 15.6 to 18.6 Ma), supporting for most of them a primary origin, however, some samples do contain older fragments that indicate glass recycling during times of enhanced glacial erosion. Most glasses are mafic (MgO=3 to 9 wt.%) and vary from hypersthene to nepheline normative with a restricted range in SiO2 (45.2±0.8 wt.%, 1σ) and trace element concentrations typical of the rift-related alkaline rocks in the Erebus Volcanic Province. The glass extends known composition of early phase Mount Morning activity (ca. 11–19 Ma), the only known Early to MiddleMiocene source, to a more mafic end, revealing a previously unknown explosive, strongly alkaline, basaltic phase and the most primitive forms of both strongly alkaline (basanite to phonolite) and moderately alkaline (alkali basalt to trachyte) magma associations. The glass-rich sediments occur in glacimarine sequences that record 56 cycles of glacial advance and retreat. Volcanic response to glacial cyclicity is observed both physically and geochemically in AND-2A glass. Higher glass volumes in sediments correlate with ice minimum conditions between 300 and 800 mbsf. Ratios of Ba to Hf, Nb, La and Zr in mafic glasses (≥5 wt.% MgO) show a systematic increase in mean values during intervals of ice retreat and decreasing values with ice expansion, suggesting tapping of magmas with variable incompatible to compatible trace element ratios. This may be related to changes in the stress state of the crust in response to rapid ice volume fluctuations over the volcano, which may influence magma chemistry by varying the duration and depth of magma storage.

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The separate effects of pressure (10 4 and 1.0 GPa), water, CO2, oxygen fugacity and calcium doping on the liquid line of descent of a primitive leucite-basanite magma (SiO2¼ 47.06 wt%, MgO¼ 12.76wt%andMg#¼ 75.1) fromthe Montefiascone Volcanic Complex (Vulsini volcanoes, central Italy) were experimentally investigated in the 1350–1160 C temperature range. Results indicate that low-pressure liquidus temperatures are 1280 C and that the high-pressure Tliquidus is 1350 C under anhydrous conditions; the latter is lowered to 1275 C by the addition of 3 wt% water. Cr-spinel is always the liquidus phase. At comparable fO2 values, high and low pressure runs produced the same phase assemblage (spinel þ olivine þ clinopyroxene) up to 50 % crystallization, although olivine was partially or totally replaced by phlogopite in hydrous experiments. An increase in oxygen fugacity and the addition of CaO determine an increase in both the degree of melt crystallization and the stability field of clinopyroxene. These determine contrasting effects on the composition of residual liquids: the former increases SiO2 content, whereas the latter induces the desilication of melts. The replacement of olivine by phlogopite, induced by increasing amounts of water, leads to the production of glass with lower potassium contents. Comparison of the natural and experimental melts shows that many of major and trace element variations exhibited by high-K primitive (i.e., highMg/Mg þ Fe) magmas at Montefiascone, are consistent with their derivation from a single parental leucite-basanite melt by fractional crystallization of different proportions of mineral phases, plus carbonate assimilation. The changes in phases stability and melt composition caused by carbonate assimilation may also have fundamental implications for the origin of the calcic highmagnesium leucitites and melilitites. In particular, the complex metasomatic interactions that can develop at the interface between potassic magmas and carbonate wall rocks, may lead to melting of calcite. This low-viscosity melt readily mixes with the surrounding magma inducing the crystallization of Ca-Tschermak-rich pyroxene and hercynitic spinel, affecting significantly the SiO2, CaO and alumina composition of the resulting hybrid melt. A key finding of our study is that magmas such as the studied leucite-basanite may be considered parental to the wide spectrum of mafic high-K compositions in the Roman Province, which have been traditionally considered as representing near primary magmas reflecting distinct mantle source compositions and/or processes.