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121.
Michael L. Humber Luigi Boschetti Louis Giglio Christopher O. Justice 《International Journal of Digital Earth》2019,12(4):460-484
We characterize the agreement and disagreement of four publically available burned products (Fire CCI, Copernicus Burnt Area, MODIS MCD45A1, and MODIS MCD64A1) at a finer spatial and temporal scale than previous assessments using a grid of three-dimensional cells defined both in space and in time. Our analysis, conducted using seven years of data (2005–2011), shows that estimates of burned area vary greatly between products in terms of total area burned, the location of burning, and the timing of the burning. We use regional and monthly units for analysis to provide insight into the variation between products that can be lost when considering products yearly and/or globally. Comparison with independent, contemporaneous MODIS active fire observations provides one indication of which products most reasonably capture the burning regime. Our results have implications for the use of global burned area products in fire ecology, management and emissions applications. 相似文献
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Giancarlo Benettin Luigi Galgani Antonio Giorgilli 《Celestial Mechanics and Dynamical Astronomy》1985,37(1):1-25
In the present paper we give a proof of Nekhoroshev's theorem, which is concerned with an exponential estimate for the stability times in nearly integrable Hamiltonian systems. At variance with the already published proof, which refers to the case of an unperturbed Hamiltonian having the generic property of steepness, we consider here the particular case of a convex unperturbed Hamiltonian. The corresponding simplification in the proof might be convenient for an introduction to the subject. 相似文献
124.
Pierre ROCHETTE Leonardo SAGNOTTI Michle BOUROT‐DENISE Guy CONSOLMAGNO Luigi FOLCO Jrme GATTACCECA Maria Luisa OSETE Lauri PESONEN 《Meteoritics & planetary science》2003,38(2):251-268
Abstract— We present a database of magnetic susceptibility measurements on 971 ordinary chondrites. It demonstrates that this parameter can be successfully used to characterize and classify ordinary chondrite meteorites. In ordinary chondrites, this rapid and non‐destructive measurement essentially determines the amount of metal in the sample, which occurs in a very narrow range for each chondrite class (though terrestrial weathering can result in a variable decrease in susceptibility, especially in finds). This technique is particularly useful not only for a rapid classification of new meteorites, but also as a check against curation errors in large collections (i.e., unweathered meteorites, the measured susceptibility of which lies outside the expected range, may well be misclassified or misidentified samples). Magnetic remanence, related to magnetic field measurements around asteroids, is also discussed. 相似文献
125.
Marco Bonini Chiara Tanini Giovanna Moratti Luigi Piccardi Federico Sani 《第四纪科学杂志》2003,18(8):695-708
This paper examines the morphotectonic and structural–geological characteristics of the Quaternary Martana Fault in the Umbria–Marche Apennines fold‐and‐thrust belt. This structure is more than 30 km long and comprises two segments: a N–NNW‐trending longer segment and a 100°N‐trending segment. After developing as a normal fault in Early Pleistocene times, the N–NNW Martana Fault segment experienced a phase of dextral faulting extending from the Early to Middle Pleistocene boundary until around 0.39 Ma, the absolute age of volcanics erupted in correspondence to releasing bends. The establishment of a stress field with a NE–ENE‐trending σ3 axis and NW–NNW σ1 axis in Late Pleistocene to Holocene times resulted in a strong component of sinistral faulting along N–NNW‐trending fault segments and almost pure normal faulting on newly formed NW–SE faults. Fresh fault scarps, the interaction of faulting with drainage systems and displacement of alluvial fan apexes provide evidence of the ongoing activity of this fault. The active left‐lateral kinematic along N–NNW‐trending fault segments is also revealed by the 1.8 m horizontal offset of the E–W‐trending Decumanus road, at the Roman town of Carsulae. We interpret the present‐day kinematics of the Martana Fault as consistent with a model connecting surface structures to the inferred north‐northwest trending lithospheric shear zone marking the western boundary of the Adria Plate. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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Data supporting relevant Late Cretaceous–Early Eocene sinistral displacement along the Giudicarie fault zone and a minor Neogene dextral displacement along the Periadriatic lineament are discussed. The pre-Adamello structural belt is present only in the internal Lombardy zone, located W of the Adamello massif. This belt is unknown in the Dolomites and surrounding areas located to the E of the Giudicarie lineament. Upper Cretaceous–Early Eocene thick syntectonic Flysch deposits of Lombardy and Giudicarie are well preserved along the southern and eastern border of the pre-Adamello belt (S-vergent Alpine orogen). Towards the E, in the Dolomites and in the Carnic Alps and external Dinarides, only incomplete remnants of Flysch deposits, Aptian–Albian and Turonian–Maastrichtian in age, are present. They can be considered as equivalent to those of Lombardy and Giudicarie formerly in connection to each other along the N-Giudicarie corridor. To the S, the syntectonic Flysch deposits are laterally replaced by the calcareous red pelagites of the Scaglia Rossa and by the carbonate shelf deposits of the Friuli (to the E) and Bagnolo (to the S) carbonate platforms. The different location in the southern structural accretion of the eastern and western opposite blocks (the Dolomites versus the pre-Adamello belt) can be related to the Cretaceous–Eocene convergence. In this frame, the N-Giudicarie fault has been considered as part of a former transfer zone, which produced the sinistral lateral displacement of the Southern Alps front for an amount of some 50 km. During the Late Eocene to Early Oligocene the transfer zone was mostly sealed by the Paleogene Adamello batholith. Oligocene to Neogene compressional evolution inverted the N-Giudicarie fault into a backthrust of the Austroalpine units over the South-Alpine chain. 相似文献
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130.
Daniela Mele Roberto Sulpizio Pierfrancesco Dellino Luigi La Volpe 《Bulletin of Volcanology》2011,73(3):257-278
New volcanological studies allow reconstruction of the eruption dynamics of the Pomici di Mercato eruption (ca 8,900 cal.
yr B.P.) of Somma-Vesuvius. Three main Eruptive Phases are distinguished based on two distinct erosion surfaces that interrupt
stratigraphic continuity of the deposits, indicating that time breaks occurred during the eruption. Absence of reworked volcaniclastic
deposits on top of the erosion surfaces suggests that quiescent periods between eruptive phases were short perhaps lasting
only days to weeks. Each of the Eruptive Phases was characterised by deposition of alternating fall and pyroclastic density
current (PDC) deposits. The fallout deposits blanketed a wide area toward the east, while the more restricted PDC deposits
inundated the volcano slopes. Eruptive dynamics were driven by brittle magmatic fragmentation of a phonolitic magma, which,
because of its mechanical fragility, produced a significant amount of fine ash. External water did not significantly contribute
either to fragmentation dynamics or to mechanical energy release during the eruption. Column heights were between 18 and 22 km,
corresponding to mass discharge rates between 1.4 and 6 × 107 kg s−1. The estimated on land volume of fall deposits ranges from a minimum of 2.3 km3 to a maximum of 7.4 km3. Calculation of physical parameters of the dilute pyroclastic density currents indicates speeds of a few tens of m s−1 and densities of a few kg m−3 (average of the lowermost 10 m of the currents), resulting in dynamic pressures lower than 3 kPa. These data suggest that
the potential impact of pyroclastic density currents of the Pomici di Mercato eruption was smaller than those of other Plinian
and sub-Plinian eruptions of Somma-Vesuvius, especially those of 1631 AD and 472 AD (4–14 kPa), which represent reference
values for the Vesuvian emergency plan. The pulsating and long-lasting behaviour of the Pomici di Mercato eruption is unique
in the history of large explosive eruptions of Somma-Vesuvius. We suggest an eruptive scheme in which discrete magma batches
rose from the magma chamber through a network of fractures. The injection and rise of the different magma batches was controlled
by the interplay between magma chamber overpressure and local stress. The intermittent discharge of magma during a large explosive
eruption is unusual for Somma-Vesuvius, as well as for other volcanoes worldwide, and yields new insights for improving our
knowledge of the dynamics of explosive eruptions. 相似文献