The author describes a subterminal radial fissure eruption of Mt. Etna that took place in February 1964. A sketchmap and a chemical analysis of the lava are given.
Zusammenfassung Der Verfasser beschreibt den subterminalen Radialspaltenausbruch des Ätnas im Februar 1964 und fügt eine chemische Analyse der geförderten Lava bei.
Résumé L'auteur décrit une éruption subterminale de l'Etna qui a eu lieu sur une fissure radiale en février 1964. Une carte de la région sommitale de l'Etna et une analyse chimique de la lava sont ajoutées.
Riassunto L'autore descrive l'eruzione radiale verificatasi al cono terminale dell'Etna nel Febbraio del 1964. Dà inoltre un rilevamento schematico della zona del cratere centrale ed il chimismo della roccia.
, 1964 .
Dedicated to Professor Dr. A.Rittmann on the occasion of his 75. birthdayThis study is a part of the researches, carried out with the funds of the National Research Council of the Italy under the direction of Prof. A.Ritmann. 相似文献
Experimental studies have been carried out in a fractured coastal aquifer of the Salento region (Nardò, Italy), which has been subjected to 12,000 m3/day of treated municipal waste water injected into a natural sinkhole since 1991. The analytical parameters of ground water sampled in 30 monitoring wells in the area down gradient from the sinkhole, taking into account the direction of ground water flow, have been compared before and after injection. The water table mound (1.5 m), the reduction of sea water extent (2 km), and the spreading of injected pollutants were evaluated by means of a mathematical model. The predicted values in the monitoring wells were adjusted to inorganic nitrogen biodegradation using transformation rates developed in laboratory tests. After 10 years, the injection has increased the volume of the available resource for agricultural and drinking water use, without any notable decrease in the preexisting ground water quality. Moreover, to preserve water resources from pollution, the mathematical model allowed the maximum constituent concentrations (standards) in waste water reclamation for recharge to be identified. A precautionary area around the sinkhole was also defined so that withdrawal prohibition could be implemented to avoid risks to human health. 相似文献
In order to unravel the tectonic evolution of the north-central sector of the Sicily Channel (Central Mediterranean), a seismo-stratigraphic analysis of single- and multi-channel seismic reflection profiles has been carried out. This allowed to identify, between 20 and 50 km offshore the central-southern coast of Sicily, a ~80-km-long deformation belt, characterized by a set of WNW–ESE to NW–SE fault segments showing a poly-phasic activity. Within this belt, we observed: i) Miocene normal faults reactivated during Zanclean–Piacenzian time by dextral strike-slip motion, as a consequence of the Africa–Europe convergence; ii) releasing and restraining bend geometries forming well-developed pull-apart basins and compressive structures. In the central and western sectors of the belt, we identified local transpressional reactivations of Piacenzian time, attested by well-defined compressive features like push-up structures and fault-bend anticlines. The reconstruction of timing and style of tectonic deformation suggest a strike-slip reactivation of inherited normal faults and the local subsequent positive tectonic inversion, often documented along oblique thrust ramps. This pattern represents a key for an improved knowledge of the structural style of foreland fold-and-thrust belts propagating in a preexisting extensional domain. With regard to active tectonics and seismic hazards, recent GPS data and local seismicity events suggest that this deformation process could be still active and accomplished through deep-buried structures; moreover, several normal faults showing moderate displacements have been identified on top of the Madrepore Bank and Malta High, offsetting the Late Quaternary deposits. Finally, inside the northern part of the Gela Basin, multiple slope failures, originated during Pleistocene by the further advancing of the Gela Nappe, reveal tectonically induced potential instability processes.
We have established a plausible rate of uplift near Siracusa in southeastern Sicily (Italy) over the last glacial–interglacial cycle using U-series ages of submerged speleothem calcite and 14C ages of calcite serpulid layers that encrust the speleothems during cave submergence. The precisely determined ages of these sea level benchmarks were compared with expected relative sea level position based on glacio-hydro-isostatic modeling to assess the rate of uplift in this region. When combined with the age of various late Holocene archaeological sites that have been recently described and characterized in terms of their functional position relative to sea level these data collectively define a rate of uplift ≤0.4 mm a?1 along this portion of the Sicilian coastline. These results are consistent with an age assignment of marine isotope stage (MIS) 5.3 or 5.5 for the Akradina terrace, which in turn places temporal constraints on paleoshorelines above and below this level. 相似文献
A novel methodology for simultaneous discharge and channel roughness estimation is developed and applied to data sets available at three experimental sites. The methodology is based on the synchronous measurement of water level data in two river sections far some kilometers from each other, as well as on the use of a diffusive flow routing solver and does not require any direct velocity measurement. The methodology is first analyzed for the simplest case of a channel with a large slope, where the kinematic assumption holds. A sensitivity and a model error analysis are carried out in this hypothesis in order to show the stability of the results with respect to the error in the input parameters in the case of homogeneous roughness and to analyze the effect of unknown roughness heterogeneity on the estimated discharges. The methodology is then extended to the more general case of channels with mild slope and validated using field data previously collected in three Italian rivers: the Arno (in Tuscany), the Tiber (in Latium) and the Vallo di Diana, a small tributary of the Tanagro river (in Southern Italy). The performance of the proposed algorithm has been investigated according to three performance criteria estimating the quality of the match between the measured and the computed stage and discharge hydrographs. Results of the field tests can be considered good, despite the uncertainties of the field data and of the measured values. 相似文献
Abstract. The grazing of Acartia hudsonica and Acartia tonsa was observed on cultures of Olisthodiscus luteus and Dunaliella tertiotecta presented alone and in combination. Feeding on D. lertiolecla by both Acartia species increased directly with concentration but was always lower at equivalent food concentrations when O. luteus was present. In mixed phytoplankton cultures, A. hudsonica fed on both species at low O. luteus concentration, only on D, lertiolecla at intermediate levels and stopped feeding at highest O. luteus concentrations. A. tonsa showed a variable but similar result. These studies indicate the possible role of these dominant herbivores on the dynamics of O. luteus populations. 相似文献
The extensive study of a great number of deep-seated xenoliths from Tortonian tuff-breccia pipes in the Hyblean area (Sicily) revealed the following fundamental evidence: (1) typical continental crust rocks are completely absent in the entire xenolith suite; (2) mantle ultramafics are more abundant than gabbroids; (3) sheared oxide–gabbros, closely resembling those from oceanic fracture zones, are relatively common; (4) secondary mineral assemblages, compatible with alteration processes in serpentinite-hosted hydrothermal systems, occur both in peridotites and gabbros. Among the products of this hydrothermal activity, organic compounds, having abiotic origin via Fischer–Tropsch synthesis, occur in some hydrothermally altered gabbro and ultramafic xenoliths, as well as in hydrothermal clays. Moreover, the U–Pb dating of hydrothermal zircon grains, hosted in a xenolith of metasomatized tectonic breccia, indicated an Early–Middle Triassic age of the fossil hydrothermal system. Another line of evidence for the oceanic nature of the Hyblean–Pelagian basement is the complete absence of continental crust lithologies (granites, felsic metaigneous, and metasedimentary rocks) in outcrops and in boreholes, and the oceanic affinity of the Tertiary volcanic rocks from the Hyblean Plateau and the Sicily Channel (Pantelleria and Linosa Islands), which lack of any geochemical signature for continental crust contamination. A reappraisal of existing geophysical data pointed out that serpentinites form the dominant lithologies in the lithospheric basement of the Hyblean–Pelagian area down to a mean depth of 19 km, which represents the regional Moho considered as the serpentinization front, marking the transition from serpentinites to unaltered peridotites. On these grounds, we confirm that Hyblean xenoliths contain mineralogical, compositional, and textural evidence for tectonic, magmatic, and hydrothermal processes indicating the existence of fossil oceanic core complexes, in the geotectonic framework of the Paleo–Mesozoic, ultra-slow spreading, Ionian–Tethys Ocean forming the present Ionian–Hyblean–Pelagian domain. 相似文献