Large Scale Rockfall Reach Susceptibility Maps in La Cabrera Sierra (Madrid) performed with GIS and Dynamic Analysis at 1:5,000   总被引：1，自引：0，他引：1  

Ayala-Carcedo  Francisco J.  Cubillo-Nielsen  Silvia  Alvarez  Ana  Domínguez  María J.  Laín  Luis  Laín  Ricardo  Ortiz  Guillermo 《Natural Hazards》2003,29(3):325-340

For the testing of the effect on the tsunami prevention facilities, a simplified methodfor tsunami risk assessment was suggested without wave run-up analysis. This methodis proposed using calculated offshore tsunami waveform and field reconnaissance suchas the seawall height, time necessary for residents' evacuation and tsunami warninginsurance. Then, two normalized values are evaluated; one is the ratio of calculatedmaximum tsunami height to seawall height, the other is the ratio of time betweentsunami over-topping and evacuation completion to total time required for evacuation.These two values are used to qualitatively estimate the safety of residents and the effectof tsunami prevention facilities, eliminating the necessity to compute complicatedtsunami run-up onshore.  相似文献   

A ‘core-complex-like structure’ formed by superimposed extension,folding and high-angle normal faulting. The Santi Petri dome (western Betics,Spain)     

Guillermo Booth-Rea  José Miguel Azañón  Vı́ctor Garcı́a-Dueñas  Romain Augier  Mario Sánchez-Gómez 《Comptes Rendus Geoscience》2003,335(2):265-274

The Santi Petri dome (western Betics, southern Spain) shows a core-complex-like structure, where migmatitic gneisses and schists outcrop below low-grade slates and phyllites, all of which form the basement of the Neogene Málaga basin. The migmatites and schists suffered a coaxial-flattening event during isothermal decompression and were later exhumed by ductile ESE non-coaxial stretching. Further exhumation was achieved by W- to SW-transport brittle low-angle normal faulting. Subsequently these extensional structures were gently folded in the core of a NE/SW-oriented antiform during the Tortonian. Finally the Santi Petri domal geometry was accentuated by the interference of orthogonal high-angle faults with ENE–WSW and NNW–SSE orientation. This core-complex-like structure, formed by superposition of extensional and compressive tectonic events, does not represent a classical, purely extensional core complex, which shows that metamorphic structure and geometry are not decisive criteria to define a core-complex.  相似文献   

“A Salute to the Bandido”: A Political Ecology of Voice Exploration into Peru’s Freedom of Voice Surrounding Hydrocarbon Development     

Adrian Gonzalez 《社会与自然资源》2018,31(6):649-665

This paper sets out to evaluate the freedom of voice for Peruvian stakeholders affected by hydrocarbon development. This occurs through the utilization of a political ecology of voice (PEV) theoretical framework based upon the theory of voice by Albert Hirschman and political ecology. PEV can be defined as the study of economic, political, social, and geographical factors over a specific time period and their impact upon the use of voice by stakeholders. Peru’s case study was focused on its main oil-producing Loreto Region and incorporated evaluation of hydrocarbon voice mechanisms (prior consultation and environmental impact assessments) supported by interview testimony of stakeholders and state officials. PEV analysis reveals a political environment which is dangerous, inflexible, and intolerant of Peruvian stakeholders voicing over hydrocarbon development. This is due to the state’s zealous pursuit of its “selva (rainforest) hydrocarbon and development vision” which severely undermines Peruvian stakeholder’s freedom of voice.  相似文献   

From platform to basin to swell: orbital control on sedimentary sequences in the Oxfordian, Spain     

André Strasser  Marc Aurell  Beatriz Bádenas  Guillermo Meléndez  Sara Tomás 《地学学报》2005,17(5):407-413

Climatic, oceanographic and ecological changes that control the formation and deposition of sediment in shallow and deep depositional environments commonly occur with periodicities of a few 10 000 years. Consequently, in order to interpret sedimentary sequences in the geological past, high time resolution is required. This is best obtained by cyclostratigraphy. Three sections have been studied in the Oxfordian of north-eastern Spain: one represents a shallow, siliciclastic-carbonate platform with repetitive subaerial exposures, one an intraplatform basin with sponge bioherms, and one a swell where iron ooids and glauconite formed. The platform section displays a well-defined stacking pattern of depositional sequences; the deeper-water sections are well dated by ammonites. The correlation between the three sections is a best-fit solution integrating biostratigraphy, sequence stratigraphy and cyclostratigraphy. It is concluded that the small-scale depositional sequences formed in tune with the 100-ka orbital eccentricity cycle. An additional factor was differential subsidence that ruled basin morphology.  相似文献   

Incorporating variable source area hydrology into a curve-number-based watershed model     

Elliot M. Schneiderman  Tammo S. Steenhuis  Dominique J. Thongs  Zachary M. Easton  Mark S. Zion  Andrew L. Neal  Guillermo F. Mendoza  M. Todd Walter 《水文研究》2007,21(25):3420-3430

Many water quality models use some form of the curve number (CN) equation developed by the Soil Conservation Service (SCS; U.S. Depart of Agriculture) to predict storm runoff from watersheds based on an infiltration-excess response to rainfall. However, in humid, well-vegetated areas with shallow soils, such as in the northeastern USA, the predominant runoff generating mechanism is saturation-excess on variable source areas (VSAs). We reconceptualized the SCS–CN equation for VSAs, and incorporated it into the General Watershed Loading Function (GWLF) model. The new version of GWLF, named the Variable Source Loading Function (VSLF) model, simulates the watershed runoff response to rainfall using the standard SCS–CN equation, but spatially distributes the runoff response according to a soil wetness index. We spatially validated VSLF runoff predictions and compared VSLF to GWLF for a subwatershed of the New York City Water Supply System. The spatial distribution of runoff from VSLF is more physically realistic than the estimates from GWLF. This has important consequences for water quality modeling, and for the use of models to evaluate and guide watershed management, because correctly predicting the coincidence of runoff generation and pollutant sources is critical to simulating non-point source (NPS) pollution transported by runoff. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Diffuse Emission of Hydrogen from Poás Volcano,Costa Rica,America Central     

Gladys V. Melián  Inés Galindo  Nemesio M. Pérez  Pedro A. Hernández  Mario Fernández  Carlos Ramírez  Raúl Mora  Guillermo E. Alvarado 《Pure and Applied Geophysics》2007,164(12):2465-2487

We report the results of four soil H₂ surveys carried out in 2000–2003 at Poás volcano, Costa Rica, to investigate the soil H₂ distribution and evaluate the diffuse H₂ emission as a potential surveillance tool for Poás volcano. Soil gas H₂ contents showed a wide range of concentration from 0.2 to 7,059 ppmV during the four surveys. Maps of soil gas H₂ based on Sequential Gaussian Simulation showed low H₂ concentration values in the soil atmosphere (<0.7 ppmV) for most of the study area, whereas high soil gas H₂ values were observed inside the active crater of Poás. A significant increase in soil gas H₂ concentration was observed inside the active crater during 2001 and 2002 with respect to year 2000, followed by a decrease in 2003. The observed spatial and temporal variations of soil H₂ concentration have been well correlated with seismicity, microgravimetry and fumarolic chemistry changes which occurred during this study. These observations evidence changes in the shallow magmatic-hydrothermal system of Poás, and it might be related to a potential magmatic intrusion during the period 1998–2004. Therefore, monitoring diffuse H₂ emission of Poás has become an important geochemical tool for the monitoring of its volcanic activity.  相似文献   

Numerical solution of the dam failure problem by the random choice method     

Guillermo Marshall  Angel N. Menendez 《Advances in water resources》1981,4(3):125-133

A numerical solution of the dam failure problem as described by the one-dimensional shallow water equations is presented. The construction of the solution is based on the random choice method consisting in the superposition of locally theoretical solutions and sampling techniques. The search of the optimal sampling is performed through the application of the random choice method to the scalar wave equation. The dam failure problem is then solved and a comparison with the theoretical solution is presented. It is shown that the random choice method computes the bore with almost infinite resolution, represents exactly the constant state behind it and calculates the depression wave with great accuracy.  相似文献   

Diffuse Component Spectra of Solar Active Regions at Submillimeter Wavelengths     

Adriana?V.?R.?SilvaEmail author  Tatiana?F.?Laganá  C.?Guillermo?Gimenez?De?Castro  Pierre?Kaufmann  Joaquim?E.?R.?Costa  Hugo?Levato  Marta?Rovira 《Solar physics》2005,227(2):265-281

Solar maps at 212 and 405 GHz obtained by the Solar Submillimetric Telescope (SST) show regions of enhanced brightness temperature, which coincide with the location of active regions. A statistical study of the radio emission from these active regions was performed for the first time at such high frequencies during 23 days on June and July 2002, when the atmospheric opacity was low. The brightest regions on the maps were chosen for this study, where the brightness excess observed varies from 3 to 20% above quiet Sun levels (i.e., 200–1000 K) at both wavelengths. Sizes of the regions of enhanced emission calculated at half the maximum value were estimated to be between 2′ and 7′. These sizes agree with observed sizes of active regions at other wavelengths such as Hα and ultraviolet. An important result is that the flux density spectra of all sources increase toward submillimeter frequencies, yielding flux density spectral index with an average value of 2.0. The flux density of the active region sources were complemented with that from maps at 17 and 34 GHz from the Nobeyama Radio Heliograph. The resulting spectra at all four frequencies were fit considering the flux density to be due to thermal bremsstrahlung from the active region. In the calculations, the source radius was assumed to be the mean of the measured values at 212 and 405 K. The effective temperatures of the radio emitting source, assumed homogeneous, obtained from this fit were 0.6–2.9 × 10⁴ K, for source diameters of 2′–7′.  相似文献   

Influence of the South Atlantic convergence zone and SouthAtlantic Sea surface temperature on interannual summerrainfall variability in Southeastern South America   总被引：1，自引：0，他引：1  

V. Barros  M. Gonzalez  B. Liebmann  I. Camilloni 《Theoretical and Applied Climatology》2000,67(3-4):123-133

Summary  In subtropical Argentina, Paraguay and southern Brazil, precipitation is most abundant during summer but its interannual variability is large. At this time a zone of low-level convergence, upper-level divergence, and intense convection is developed to the north of this area. This feature is known as the South Atlantic convergence zone (SACZ) and seems to be related to the interannual variability of summer rainfall to its south. The aim of this work is to document this relationship. Reduced (increased) precipitation in southern Brazil, most of Uruguay and northeastern Argentina is associated with a strong (weak) SACZ and a northward (southward) displacement of it, while increased (reduced) rainfall occurs further south in subtropical Argentina. Also, warm (cold) SST in the region 20° S–40° S and west of 30° W is likely accompanied by a southward (northward) shift of the SACZ. Aside of this relation with the SACZ that affect on the precipitation field of Southeastern South America, the proximate Atlantic Ocean SST seems to force the precipitation over this region by other mechanisms as well. The result of this additional SST forcing is to enhance the signal of the SACZ in northeastern Argentina, Uruguay and southern Brazil and to oppose the SACZ effect in southern subtropical Argentina. Received July 24, 1999 Revised July 5, 2000  相似文献   

The 2005 eruption of Ilamatepec (Santa Ana) volcano,El Salvador     

Teresa Scolamacchia  Carlos Pullinger  Lizeth Caballero  Francisco Montalvo  Laura E. Beramendi Orosco  Galia Gonzalez Hernández 《Journal of Volcanology and Geothermal Research》2010,189(3-4):291-318

We report the stratigraphic sequence of the 2005 eruption of Ilamatepec volcano together with sedimentological and chemical analyses of its products.Structural and textural characteristics of the deposits indicate that the eruption was driven by a small-volume rhyolitic intrusion at shallow levels, which resulted first in the collapse of the existing hydrothermally altered fan of previous deposits inside the crater lake, driving phreatic explosions with launching of blocks on ballistic trajectories; later the magma interacted with lake waters producing several hydromagmatic pyroclastic density currents (PDCs). These flows were energetic enough to knock down pine trees up to distances of 1.8 km from the crater in the E-NE sector of the volcano. Finally, ejection of ballistic blocks that landed on previously emplaced, wet pyroclastic density current deposits, caused the generation of a lahar that flowed down the steep eastern flank toward the El Jabillal gully. Subsequent lahars occurred as a result of intense rain caused by hurricane Stan.Radiocarbon ages on paleosols and charcoal fragments, separating previous volcanogenic sequences, indicate that similar eruptions have occurred more frequently in the past centuries, than previously thought.The new data confirms that Ilamatepec volcano is one of the most active volcanoes in El Salvador. Nevertheless, more detailed studies of the eruptive sequence of Ilamatepec volcano are mandatory to establish future eruptive patterns.  相似文献