Simultaneous simulation of the three components of seismic accelerograms at locations around seismological stations     

Chiesa  Daniela Dalla  Miguel  Letícia Fleck Fadel  Riera  Jorge Daniel 《Journal of Seismology》2021,25(6):1361-1384

Journal of Seismology - This paper proposes a new numerical procedure, based on an evolutionary optimization algorithm, for the simultaneous generation of the three components of the seismic ground...  相似文献   

Living with Earthquakes in California: Robert S. Yeats (Oregon State University Press, Corvallis, OR, 2001, pp. 406, ISBN 0-87071-493-7, $21.95)     

Daniela Pantosti   《Tectonophysics》2002,344(1-2)

  相似文献   

The robustness of the Zr-in-rutile and Ti-in-zircon thermometers during high-temperature metamorphism (Ivrea-Verbano Zone, northern Italy)   总被引：3，自引：0，他引：3  

Tanya A. Ewing  Jörg Hermann  Daniela Rubatto 《Contributions to Mineralogy and Petrology》2013,165(4):757-779

This study investigates the behaviour of the Zr-in-rutile and Ti-in-zircon thermometers in granulite facies metapelites from the Ivrea-Verbano Zone lower crustal section. U–Pb ages of zircon constrain the timing of regional amphibolite–granulite facies metamorphism to 316 ± 3 Ma and record zircon recrystallisation and resetting of U–Pb ages at 276 ± 4 Ma and 258 ± 3 Ma. Zr-in-rutile thermometry records peak contact metamorphic temperatures related to intrusion of mafic magmatic rocks and gives peak temperatures between 900–930 °C and 1,000–1,020 °C that are consistent with the geological settings of the samples. Ti-in-zircon temperatures of 700–800 °C and 810–870 °C record growth or re-equilibration of zircon after cooling from peak temperatures. Ti-in-quartz thermometry for one sample records both peak and retrograde temperatures. Some rutiles in all samples record resetting of Zr-in-rutile temperatures at ~750–800 °C. Electron microprobe profiles across individual rutiles demonstrate that Zr expulsion occurred by recrystallisation rather than by diffusive exchange. Exsolution of small needles of baddelyite or zircon from rutile is an important method of Zr redistribution, but results in no net Zr loss from the grain. The demonstration that Zr-in-rutile thermometry can robustly record peak temperatures that are not recorded by any other thermometer emphasises the relevance of this technique to investigating the evolution of high-grade metamorphic terranes, such as those that characterise the lower crust.  相似文献   

Timescales of crustal melting in the Higher Himalayan Crystallines (Sikkim, Eastern Himalaya) inferred from trace element-constrained monazite and zircon chronology   总被引：11，自引：0，他引：11  

Daniela Rubatto  Sumit Chakraborty  Somnath Dasgupta 《Contributions to Mineralogy and Petrology》2013,165(2):349-372

The petrology and timing of crustal melting has been investigated in the migmatites of the Higher Himalayan Crystalline (HHC) exposed in Sikkim, India. The metapelites underwent pervasive partial melting through hydrous as well as dehydration melting reactions involving muscovite and biotite to produce a main assemblage of quartz, K-feldspar, plagioclase, biotite, garnet ± sillimanite. Peak metamorphic conditions were 8–9 kbar and ~800 °C. Monazite and zircon crystals in several migmatites collected along a N–S transect show multiple growth domains. The domains were analyzed by microbeam techniques for age (SHRIMP) and trace element composition (LA-ICP-MS) to relate ages to conditions of formation. Monazite preserves the best record of metamorphism with domains that have different zoning pattern, composition and age. Zircon was generally less reactive than monazite, with metamorphic growth zones preserved in only a few samples. The growth of accessory minerals in the presence of melt was episodic in the interval between 31 and 17 Ma, but widespread and diachronous across samples. Systematic variations in the chemical composition of the dated mineral zones (HREE content and negative Eu anomaly) are related to the variation in garnet and K-feldspar abundances, respectively, and thus to metamorphic reactions and P–T stages. In turn, this allows prograde versus decompressional and retrograde melt production to be timed. A hierarchy of timescales characterizes melting which occurred over a period of ~15 Ma (31–17 Ma): a given block within this region traversed the field of melting in 5–7 Ma, whereas individual melting reactions lasted for time durations below, or approaching, the resolution of microbeam dating techniques (~0.6 Ma). An older ~36 Ma high-grade event is recorded in an allocthonous relict related to mafic lenses. We identify two sections of the HHC in Sikkim that traversed similar P–T conditions at different times, separated by a tectonic discontinuity. The higher structural levels reached melting and peak conditions later (~26–23 Ma) than the lower structural levels (~31–27 Ma). Diachronicity across the HHC cannot be reconciled with channel flow models in their simplest form, as it requires two similar high-grade sections to move independently during collision.  相似文献   

A multidisciplinary approach for rock spreading and block sliding investigation in the north-western coast of Malta   总被引：2，自引：0，他引：2  

Matteo Mantovani  Stefano Devoto  Emanuele Forte  Arianna Mocnik  Alessandro Pasuto  Daniela Piacentini  Mauro Soldati 《Landslides》2013,10(5):611-622

Landslides are widespread along the north-western coast of the Island of Malta and are strictly linked to the structural setting. Exemplary cases of rock spreading and block sliding phenomena characterise this stretch of coast. They are favoured by the overposition of two different geological units widely outcropping there, the Blue Clay Formation and the Upper Coralline Limestone Formation. The latter forms a wide plateau, bordered by vertical cliffs. At the foot of the cliffs, clayey terrains crop out and develop gentle slopes covered by large blocks detached and moved by rock spreading and block sliding phenomena. These mass movements are favoured by the fragile behaviour of limestones, which cap clays, otherwise characterised by visco-plastic properties. In order to investigate the kinematics and the evolution of these types of coastal landslides, a multidisciplinary and multitechnical approach was applied on a study site, named Il-Prajjet, which provides a spectacular case of rock spreading evolving into block sliding. This paper illustrates the results achieved by means of different engineering geological and geophysical techniques allied with traditional detailed geomorphological survey and mapping. In particular, the surface displacements of the landslides were determined using long-term GPS observations, acquired approximately every 6 months, over a 4.5-year period. A network of GPS benchmarks were distributed on the edge of a limestone plateau affected by rock spreading and on a series of displaced blocks making up a large block slide, finally enabling the definition of the state of activity and the rates of movement to be performed. In addition, the results deriving from two continuous fissurimeters more recently installed at the edge of two persistent joints over the block sliding area are outlined, with reference to the correlation between variations of crack apertures and precipitation input. In order to identify main structural discontinuities and to reconstruct variability of underground surface contact between clays and overlying limestones, Resistivity Tomography profiles and GPR investigations were carried out. Finally, the results obtained by combining the outputs of geophysical surveys and different field monitoring activities can be considered a first step on which numerical models can be developed and validated, in order to assess landslide hazard and risk of this stretch of Maltese coastline.  相似文献   

An integrated approach to environmental quality assessment in a coastal setting in Campania (Southern Italy)   总被引：1，自引：1，他引：0  

Rosa Verde  Marco Vigliotti  Lidia Prevedello  Mario Sprovieri  Daniela Ruberti 《Environmental Earth Sciences》2013,70(1):407-424

The coastal region of Southern Italy’s Caserta province, known as the Litorale Domitio (Domitia coast) has been subjected to increasing pressure from unsustainably fast economic and urban growth in the last century, that resulted in a induced serious land degradation. To obtain a comprehensive picture of the ecological status of the Domitia coastal zone (Campania, Southern Italy), a holistic methodology has been applied. Sedimentological, geochemical, and biological analyses of the surface sediments and water samples were performed along the submerged beach. The data were integrated using a geographical information system, together with information on past and present land use and human activities along the coast and in inland regions. Heavy metal concentrations in sediments plus As and Se (Cd, Co, Cr, Cu, Hg, Ni, Pb, V, Zn) and their enrichment factors, which are important for identifying polluted areas in countries like Italy (where environmental legislation has not yet established intervention limits), indicate excesses Cd, Cr, Pb, and V of probable anthropogenic origin. A microbiological contamination of marine waters has been detected by the Regional Environmental Protection Agency of Campania. The Bacteriological Quality Index map shows that bathing areas must be classified as “contaminated” and “highly contaminated”. High levels of chemical and biological contamination are particularly common in both bathing seawater and sediments along the coastal zone south of the Volturno River, where the existing wastewater treatment plant is not properly working, to date. Factory farming, which is widespread in the area, is likely to be an additional important source of contamination. In accordance with these conclusions, analyses of the benthic diatom community revealed dominance of eutrophic species.  相似文献   

Experiments and Numerical Simulations on the Mid-Term Evolution of Hypersonic Jets     

Marco Belan  Sergio de Ponte  Silvano Massaglia  Daniela Tordella 《Astrophysics and Space Science》2004,293(1-2):225-232

The experiment described here is focussed to the observation of underexpanded, hypersonic turbulent jets. The experiment is relevant to a few aspects concerning the dynamics of astrophysical phenomena such as the Herbig-Haro jets and to the interaction between the large-scale vortices and the system of shocks that determine the spreading and entrainment properties of highly compressible free-flows. A number of orifice jets with a ratio between the stagnation pressure and the ambient pressure of the order 10³-10⁴ have been studied by changing the stagnation/ambient density ratio. This has been realized using dissimilar gases in the jet and in the ambient medium: by using He, Ar and air the stagnation/ambient density ratio can be changed by one order of magnitude while keeping fixed the pressure ratio. It has been possible to visualize the near and mid-term evolution of the jets and measure the axial and transversal density distributions. A comparison relevant to the shock waves configuration in between the nozzle exit and the first Mach's disk is shown for an air in air laboratory jet and its numerical simulation.  相似文献   

Impurities and heterogeneity in pyrite: Influences on electrical properties and oxidation products     

Kaye S. Savage  Daniela StefanStephen W. Lehner 《Applied Geochemistry》2008

Macroscopic pyrite crystals originating from a variety of geologic settings were made into thick sections. Electrical properties were measured with a Hall system, and minor element composition was analyzed with laser ablation inductively coupled plasma mass spectroscopy (LA-ICPMS). Selected thick sections were oxidized in a moist air environment inside a glove chamber. The relative metal content of surface products formed during oxidation was analyzed by LA-ICP-MS. Natural pyrite exhibits a range of electrical properties corresponding to the content of the common minor elements Co, As and Ni. These properties are similar to those of synthetic pyrite doped with single elements. Pyrite enriched in Co is an n-type semiconductor with low resistivity and high carrier mobility, while arsenian pyrite tends to be p-type and have higher resistivity. The effect of Ni is weaker and tends to be obscured by Co and As in samples of mixed composition. Cobalt demonstrates the strongest effect on electrical properties. Enrichment of Co at oxidized pyrite surfaces is inversely correlated with its concentration in the underlying pyrite. Cobalt enrichment in oxidation products is also more pronounced along crystal defects such as fractures, and in crystals with heterogeneous distribution of trace elements. These observations might be explained by differences in the electronic structure of pyrite arising from the presence of impurities, and by the distribution of domains with different impurity compositions, facilitating electron transfer.  相似文献   

Middle Pleistocene to Holocene activity of the Gondola Fault Zone (Southern Adriatic Foreland): Deformation of a regional shear zone and seismotectonic implications     

Domenico Ridente  Umberto Fracassi  Daniela Di Bucci  Fabio Trincardi  Gianluca Valensise 《Tectonophysics》2008,453(1-4):110

Recent seismicity in and around the Gargano Promontory, an uplifted portion of the Southern Adriatic Foreland domain, indicates active E–W strike-slip faulting in a region that has also been struck by large historical earthquakes, particularly along the Mattinata Fault. Seismic profiles published in the past two decades show that the pattern of tectonic deformation along the E–W-trending segment of the Gondola Fault Zone, the offshore counterpart of the Mattinata Fault, is strikingly similar to that observed onshore during the Eocene–Pliocene interval. Based on the lack of instrumental seismicity in the south Adriatic offshore, however, and on standard seismic reflection data showing an undisturbed Quaternary succession above the Gondola Fault Zone, this fault zone has been interpreted as essentially inactive since the Pliocene. Nevertheless, many investigators emphasised the genetic relationships and physical continuity between the Mattinata Fault, a positively active tectonic feature, and the Gondola Fault Zone. The seismotectonic potential of the system formed by these two faults has never been investigated in detail. Recent investigations of Quaternary sedimentary successions on the Adriatic shelf, by means of very high-resolution seismic–stratigraphic data, have led to the identification of fold growth and fault propagation in Middle–Upper Pleistocene and Holocene units. The inferred pattern of gentle folding and shallow faulting indicates that sediments deposited during the past ca. 450 ka were recurrently deformed along the E–W branch of the Gondola Fault Zone.We performed a detailed reconstruction and kinematic interpretation of the most recent deformation observed along the Gondola Fault Zone and interpret it in the broader context of the seismotectonic setting of the Southern Apennines-foreland region. We hypothesise that the entire 180 km-long Molise–Gondola Shear Zone is presently active and speculate that also its offshore portion, the Gondola Fault Zone, has a seismogenic behaviour.  相似文献   

A Case Study of the Performance of Different Detrending Methods in Turbulent-Flux Estimation   总被引：1，自引：1，他引：0  

Antonio Donateo  Daniela Cava  Daniele Contini 《Boundary-Layer Meteorology》2017,163(1):19-40

Observations using a three-dimensional scanning coherent Doppler lidar in an urban area revealed the characteristics of streaky structures above a rough, inhomogeneous surface for a high-Reynolds-number flow. The study focused on two points: (1) the frequency of occurrence and conditions required for the presence of streaky structures, and (2) the universal scaling of the spacing of streaky structures (\(\lambda )\). The horizontal snapshots of the radial velocity were visually classified into six groups: Streak, Mixed, Fishnet, No streak, Front, and Others. The Streak category accounted for more than 50% of all possible flows and occurred when the horizontal wind speed was large and the atmospheric stratification was near-neutral. The spacing (\(\lambda )\) was estimated from the power spectral density of the streamwise velocity fluctuations along the spanwise direction. The spacing \(\lambda \) decreased with an increase in the local velocity gradient. Furthermore, it was revealed that the local velocity gradient normalized by the friction velocity and the boundary-layer height (\(z_i )\) comprehensively predicts \(\lambda /z_i \) under various experimental and environmental conditions, in terms of the scale of motion (i.e., indoor and outdoor scales), thermal stratification (i.e., from weakly unstable to stable stratification), and surface roughness (i.e., from flat to very rough surfaces).  相似文献