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1.
Alberto Longo Manuel Pastor Lorenzo Sanavia Diego Manzanal Miguel Martin Stickle Chuan Lin Angel Yague Saeid Moussavi Tayyebi 《国际地质力学数值与分析法杂志》2019,43(5):833-857
Classical depth-integrated smoothed particle hydrodynamics (SPH) models for avalanches are extended in the present work to include a μ(I)− rheological model enriched with a fragmentation law. With this improvement, the basal friction becomes grain distribution dependent. Rock avalanches, where grain distribution tends to change with time while propagating, are the appropriate type of landslide to apply the new numerical proposal. The μ(I)− rheological models considered in the present work are those of Hatano and Gray, combined with two different fragmentation laws, a hyperbolic and a fractal-based law. As an application, Frank avalanche, which took place in Canada in 1903, is analyzed under the scope of the present approach, focusing in the influence of the rheological and fragmentation laws in the evolution of the avalanche. 相似文献
2.
3.
Natural Hazards - The deltaic coast of Myanmar was severely hit by tropical cyclone Nargis in May 2008. In the present study, a top-down numerical simulation approach using the Weather Research and... 相似文献
4.
Alatorre-Ibargüengoitia Miguel A. Hernández-Urbina Karina Ramos-Hernández Silvia G. 《Natural Hazards》2021,106(1):1011-1035
Natural Hazards - The 1982 eruption of El Chichón volcano constitutes the worst volcanic disaster in Mexico producing more than 2000 fatalities, thousands of displaced people and severe... 相似文献
5.
Oswaldo Siga Leonardo Fadel Cury Ian McReath Ligia Maria de Almeida Leite Ribeiro Kei Sato Miguel Ângelo Stipp Basei Cláudia Regina Passarelli 《Gondwana Research》2011,19(1):260-274
The results of geological mapping, chemical analysis and radiometric dating of metabasic rocks of Betara Formation, and mapping and dating of those present in the Betara basement nucleus together with mylonitic granodiorite and syenogranite are reported here. U–Pb analysis of bulk zircon fractions from the metabasic rocks of the basement nucleus yielded a Statherian age of 1790 ± 22 Ma, while the metabasic rocks from the upper part of the Betara Formation yielded a Calymmian age between 1500 and 1450 Ma. This age is a minimum for the deposition of the Betara Formation. The older metabasic rocks are associated with post-tectonic, possibly anorogenic syenogranite, while the younger ones are gabbro or very porphyritic ankaramite whose REE patterns are consistent with crystallization from an N-MORB parent magma. The observations and data point to the probable events associated with extensional processes of the end of Paleoproterozoic and early Mesoproterozoic. Similar registers of Statherian (1.80–1.75 Ga) and Calymmian (1.50–1.45 Ga) extensional events are recorded in other parts of the South American and African continents. The Neoproterozoic witnessed the formation and junction of the tectonic slices which formed the Apiaí domain during the assemblage of western Gondwana. 相似文献
6.
Manuel Ruiz-Pérez Fátima Franco-Múgica Miguel A. Alberruche-Rico 《Ocean & Coastal Management》2011,54(8):585-592
FishBanks, a well-known fisheries management simulation game, was used to test the effect of institutional settings on the biological and economic performance of fisheries. The game was played by 48 groups of between 20 and 25 undergraduate Environmental Science students in two different time lengths (10 years versus 15 years) and institutional settings (open access versus regulated access through a resource management regime). Sessions run under an institutional regime for resource management performed better than those under open access in terms of fish population, aggregate asset value and income distribution amongst competing companies. Fleet size, a proxy for human pressure on the resource, had a more intense effect than the existence or not of an institutional setting. Results also indicate that once a critical threshold is reached in stock deterioration, institutions may be insufficient to revert change, suggesting ultimate environmental limits to the effectiveness of institutions. 相似文献
7.
Human-induced coastal landslide reactivation. Monitoring by PSInSAR techniques and urban damage survey (SE Spain) 总被引:1,自引:1,他引:0
8.
Alexandre Raphael Cabral Bernd Lehmann Miguel Tupinambá Michael Wiedenbeck Michael Brauns 《Journal of Geochemical Exploration》2011
The Palaeo-Mesoproterozoic metasiliciclastic rocks of the southern Serra do Espinhaço, Minas Gerais, Brazil, are host to historically important alluvial deposits of diamonds and gold. Detrital gold grains often comprise Au–Pd–Pt intermetallic compounds, with low Ag contents, which contain inclusions of tourmaline and titaniferous hematite (up to ~ 6 wt.% TiO2). The latter minerals connect the alluvial mineralisation to the rutile–hematite–quartz veins and tourmalinisation observed in the quartzitic country rocks of the alluvial gravel. The quartzite (Sopa-Brumadinho Formation of lacustrine to fan-deltaic origin) is affected by pervasive B metasomatism with F-bearing tourmaline replacing the recrystallised quartz fabric. The tourmaline belongs to the alkali group, with Mg/(Mg + Fe) and X/(X + Na) ratios in the ranges from 0.5 to 0.7 and 0.18 to 0.29, respectively, where X represents vacancies in the X site. Boron-isotopic values of tourmaline vary from ~ 1 to − 10.4‰ δ11B. The B-isotope range, in conjunction with the Na–Mg-rich tourmaline composition, and the widespread occurrence of tourmalinite in the Sopa-Brumadinho Formation suggest a derivation from non-marine evaporitic brines. Brines are capable of transporting otherwise immobile Ti and explain, under oxidising conditions, the fractionation of Ag from Pd to precipitate palladiferous gold with extremely high Pd/Ag ratios. Zirconium-in-rutile and Ti-in-quartz temperatures for a variety of hematite-rich veins suggest episodic vein emplacement over a temperature range from around 500 °C to ~ 350 °C. Cross-cutting relationships and episodic vein emplacement indicate a late-Brasiliano age. 相似文献
9.
Mabel Mena Avto Goguitchaichvili Miguel Cervantes Solano Juan Francisco Vilas 《Studia Geophysica et Geodaetica》2011,55(2):279-309
The Early Cretaceous may be considered a key period for understanding the evolution of the Earth’s magnetic field. Some still
unsolved problems are related to the mode of paleosecular variation (PSV) of the Earth’s magnetic field before and during
the Cretaceous Normal Superchron. We report here a detailed rock-magnetic, paleomagnetic and paleointensity investigation
from 28 lava flows (331 standard paleomagnetic cores) collected in the Argentinean part of the Parana Flood Basalts (Formation
Posadas) in order to contribute to the study of PSV during the early Cretaceous and to obtain precise Cretaceous paleomagnetic
pole positions for stable South America. The average paleofield direction is precisely determined from 26 sites, which show
small within-site dispersion and high directional stability. Five sites show evidences for the self-reversal of thermoremanent
magnetization. 23 sites yielded normal polarity magnetization and only 3 are reversely magnetized. Moving windows averages
were used to analyze the sequential variation of virtual geomagnetic pole’s (VGP) axial positions. Interestingly, the axial
average VGP path traces an almost complete cycle around the geographical pole and passes near the location of all previously
published Paraná Magmatic Province poles. Both paleomagnetic poles and average VGP paths are significantly different from
the pole position suggested by fixed hotspot reconstructions, which may be due to true polar wander or the hotspot motion
itself. Only 15 samples from 5 individual basaltic lava flows, yielded acceptable paleointensity estimates. The site mean
paleointensities range from 25.2 ± 2.2 to 44.0 ± 2.2 μT. The virtual dipole moments (VDMs) range from 4.8 to 9.9 × 1022 Am2. This correspond to a mean value of 7.7 ± 2.1 × 1022 Am2 which is 96% of the present day geomagnetic field strength. These intensities agree with the relatively high values already
reported for Early Cretaceous, which are consistent with some inferences from computer simulations previously published. 相似文献
10.
Mariano Moreno‐de las Heras Rubén Díaz‐Sierra José M. Nicolau Miguel A. Zavala 《地球表面变化过程与地形》2011,36(10):1367-1377
The management of reclaimed slopes derived from industrial and civil activities (e.g. surface mining and road construction) requires the development of practical stability analysis approaches that integrate the processes and mechanisms that rule the dynamics of these ubiquitous emerging ecosystems. This work describes a new modelling approach focused on stability analysis of water‐limited reclaimed slopes, where interactive relationships between rill erosion and vegetation regulate ecosystem stability. Our framework reproduces two main groups of possible trends along the temporal evolution of reclaimed slopes: successful trends, characterized by widespread vegetation development and the effective control of rill erosion processes; and gullying trends, characterized by the progressive loss of vegetation and a sharp logistic increase in erosion rates. Furthermore, this analytical approach allows the determination of threshold values for the state variables (i.e. vegetation cover and rill erosion) that drive the system's stability, facilitating the identification of critical situations that require specific human intervention (e.g. revegetation or, in very problematic cases, revegetation combined with rill network destruction) to ensure the long‐term sustainability of the restored ecosystem. The application of our threshold analysis framework in Mediterranean‐dry reclaimed slopes derived from surface coal mining (the Teruel coalfield in central‐eastern Spain) showed a good field‐based performance. Therefore, we believe that this model is a valuable contribution for the management of water‐limited reclaimed systems, including those associated with rill erosion, as it provides a tool for the evaluation of restoration success and can play an important role in decision‐making during ecosystem restoration in severely disturbed landscapes. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献