Out‐of‐plane behaviour of a full scale stone masonry façade. Part 2: shaking table tests     

Alexandre A. Costa  António Arêde  Alfredo Campos Costa  Andrea Penna  Aníbal Costa 《地震工程与结构动力学》2013,42(14):2097-2111

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Slow cooling versus episodic fluid injections: Deciphering the Caledonian orogeny in Vestvågøy,Lofoten islands,Norway     

Herbert W. Fournier  James K. W. Lee  Alfredo Camacho 《Journal of Metamorphic Geology》2019,37(6):769-793

The determination of the thermal (temperature–time) histories of high‐P metamorphic terranes has been commonly based on the concepts of slow cooling and closure temperatures. In this paper, we find that this approach cannot reconcile a geochronological data set obtained from the amphibolite‐facies allochthonous Leknes Group of the Lofoten islands, Norway, which reveals an extremely complex thermal history. Using detailed results from several different geochronometers such as ⁴⁰Ar/³⁹Ar, Rb–Sr and U–Pb, we show that a model invoking multiple, short‐lived thermal pulses related to hot‐fluid infiltration channelized by shear zones can reconcile this complicated data set. This model suggests that hot fluids infiltrated throughout basement shear zones and affected the overlying cold allochthon, partially resetting U/Pb rutile and titanite ages, crystallizing new zircon and produced identical ⁴⁰Ar/³⁹Ar and Rb/Sr ages in muscovite, biotite and amphibole in various rocks throughout the region. This paper shows the enormous potential of coupling laser Ar‐spot data with thermal modelling to identify and constrain the duration of short‐lived events. An optimal P–T–t history has been derived by modelling the age data from a previously dated large muscovite crystal (Hames & Andresen, 1996, Geology, 24 :1005) and using Zr‐in‐rutile thermometry which is consistent with all geochronological data and geological constraints from the basement zones and allochthon cover. This tectonothermal model history suggests that there have been three episodic hot‐fluid and ⁴⁰Ar‐free infiltration events, resulting in the total resetting of Ar ages during the Scandian (425 Ma) for 1 Ma at 650°C and two reheating events at 415 Ma for 400 ka at 650°C and at 365 Ma for 50 ka at 600°C, which are modelled as thermal spikes above an ambient temperature of 300°C. Independent confirmation of these parameters was provided by Pb‐diffusion modelling in rutile and titanite. The model suggests that the amphibolite facies rocks of the Leknes Group probably remained cold before being exhumed for at least 60 Ma (425–365 Ma) and successfully explains the presence of different minerals that crystallized or were totally/partially reset in the allochthon and in the basement. The migration of hot fluids for short periods of times within conduits extending through the basement and allochthon rock units is likely associated with episodic seismic activity during the Caledonian orogeny.  相似文献   

Vegetation Index Methods for Estimating Evapotranspiration by Remote Sensing   总被引：2，自引：0，他引：2  

Edward P. Glenn  Pamela L. Nagler  Alfredo R. Huete 《Surveys in Geophysics》2010,31(6):531-555

Evapotranspiration (ET) is the largest term after precipitation in terrestrial water budgets. Accurate estimates of ET are needed for numerous agricultural and natural resource management tasks and to project changes in hydrological cycles due to potential climate change. We explore recent methods that combine vegetation indices (VI) from satellites with ground measurements of actual ET (ET_a) and meteorological data to project ET_a over a wide range of biome types and scales of measurement, from local to global estimates. The majority of these use time-series imagery from the Moderate Resolution Imaging Spectrometer on the Terra satellite to project ET over seasons and years. The review explores the theoretical basis for the methods, the types of ancillary data needed, and their accuracy and limitations. Coefficients of determination between modeled ET_a and measured ET_a are in the range of 0.45–0.95, and root mean square errors are in the range of 10–30% of mean ET_a values across biomes, similar to methods that use thermal infrared bands to estimate ET_a and within the range of accuracy of the ground measurements by which they are calibrated or validated. The advent of frequent-return satellites such as Terra and planed replacement platforms, and the increasing number of moisture and carbon flux tower sites over the globe, have made these methods feasible. Examples of operational algorithms for ET in agricultural and natural ecosystems are presented. The goal of the review is to enable potential end-users from different disciplines to adapt these methods to new applications that require spatially-distributed ET estimates.  相似文献   

Deconvolution of multicomponent seismic data by means of quaternions: Theory and preliminary results‡     

Giovanni M. Menanno  Alfredo Mazzotti 《Geophysical Prospecting》2012,60(2):217-238

Multicomponent seismic data are acquired by orthogonal geophones that record a vectorial wavefield. Since the single components are not independent, the processing should be performed jointly for all the components. In this contribution, we use hypercomplex numbers, specifically quaternions, to implement the Wiener deconvolution for multicomponent seismic data. This new approach directly derives from the complex Wiener filter theory, but special care must be taken in the algorithm implementation due to the peculiar properties of quaternion algebra. Synthetic and real data examples show that quaternion deconvolution, either spiking or predictive, generally performs superiorly to the standard (scalar) deconvolution because it properly takes into account the vectorial nature of the wavefields. This provides a better wavelet estimation and thus an improved deconvolution performance, especially when noise affects differently the various components.  相似文献   

Influence of substrate tectonic heritage on the evolution of composite volcanoes: Predicting sites of flank eruption, lateral collapse, and erosion     

Alessandro Tibaldi  Claudia Corazzato  Andrey Kozhurin  Alfredo F.M. Lagmay  Federico A. Pasquar  Vera V. Ponomareva  Derek Rust  Daniel Tormey  Luigina Vezzoli 《Global and Planetary Change》2008,61(3-4):151-174

This paper aims to aid understanding of the complicated interplay between construction and destruction of volcanoes, with an emphasis on the role of substrate tectonic heritage in controlling magma conduit geometry, lateral collapse, landslides, and preferential erosion pathways. The influence of basement structure on the development of six composite volcanoes located in different geodynamic/geological environments is described: Stromboli (Italy), in an island arc extensional tectonic setting, Ollagüe (Bolivia–Chile) in a cordilleran extensional setting, Kizimen (Russia) in a transtensional setting, Pinatubo (Philippines) in a transcurrent setting, Planchon (Chile) in a compressional cordilleran setting, and Mt. Etna (Italy) in a complex tectonic boundary setting. Analogue and numerical modelling results are used to enhance understanding of processes exemplified by these volcanic centres. We provide a comprehensive overview of this topic by considering a great deal of relevant, recently published studies and combine these with the presentation of new results, in order to contribute to the discussion on substrate tectonics and its control on volcano evolution. The results show that magma conduits in volcanic rift zones can be geometrically controlled by the regional tectonic stress field. Rift zones produce a lateral magma push that controls the direction of lateral collapse and can also trigger collapse. Once lateral collapse occurs, the resulting debuttressing produces a reorganization of the shallow-level magma migration pathways towards the collapse depression. Subsequent landslides and erosion tend to localize along rift zones. If a zone of weakness underlies a volcano, long-term creep can occur, deforming a large sector of the cone. This deformation can trigger landslides that propagate along the destabilized flank axis. In the absence of a rift zone, normal and transcurrent faults propagating from the substrate through the volcano can induce flank instability in directions respectively perpendicular and oblique to fault strike. This destabilization can evolve to lateral collapse with triggering mechanisms such as seismic activity or magmatic intrusion.  相似文献   

Investigating the Tsunamigenic Potential of Earthquakes from Analysis of the Informational and Multifractal Properties of Seismograms     

Luciano Telesca  Ashutosh Chamoli  Michele Lovallo  Tony Alfredo Stabile 《Pure and Applied Geophysics》2015,172(7):1933-1943

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Geophysical Exploration of Fractured-Media Aquifers at the Mexican Mesa Central: Satellite City,San Luis Potosí, Mexico     

Héctor López Loera  José Alfredo Ramos Leal  Pablo Dávila Harris  David Ernesto Torres Gaytan  Victor Julian Martinez Ruiz  Avto Gogichaishvili 《Surveys in Geophysics》2015,36(1):167-184

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Expansion of an invasive coral species over Abrolhos Bank,Southwestern Atlantic     

Thiago J.F. Costa  Hudson T. Pinheiro  João Batista Teixeira  Eric F. Mazzei  Leonardo Bueno  Mike S.C. Hora  Jean-Christophe Joyeux  Alfredo Carvalho-Filho  Gilberto Amado-Filho  Claudio L.S. Sampaio  Luiz A. Rocha 《Marine pollution bulletin》2014

Invasive coral species of the genus Tubastraea have been increasingly recorded in Southwestern Atlantic waters since the 1980s. Their invasion and infestation are mainly related to port and oil exploration activities. For the first time the presence of Tubastraea tagusensis colonies is reported in Espírito Santo State, colonizing a port shore area, and incrusting oil/gas platform structures situated in the southern Abrolhos Bank, which is part of the most important coral reef system of the South Atlantic Ocean. Tubastraea colonies exhibit fast growth and high recruitment rates, and colonized 40% of the analyzed structures in just four years. The projection of port and oil/gas industry growth for the Espírito Santo State (more than 300%) highlights an alert to the dispersal of this alien species to natural areas.  相似文献   

Charnock’s Roughness Length Model and Non-dimensional Wind Profiles Over the Sea   总被引：1，自引：1，他引：0  

Alfredo Peña  Sven-Erik Gryning 《Boundary-Layer Meteorology》2008,128(2):191-203

An analysis tool for the study of wind speed profiles over the water has been developed. The profiles are analysed using a modified dimensionless wind speed and dimensionless height, assuming that the sea surface roughness can be predicted by Charnock’s roughness length model. In this form, the roughness dependency on wind speed is extracted and the variations on the wind profile are due solely to atmospheric stability. The use of the Charnock’s non-dimensional wind profile is illustrated using data collected from a meteorological mast installed in the Danish North Sea. The best fit with the observed mean non-dimensional wind profile under neutral atmospheric conditions is found using a value of 1.2 × 10⁻² for Charnock’s parameter. The stability correction on the neutral wind profile suggested by the Businger-Dyer relations was found to perform well over the sea.  相似文献   

Measurements and Modelling of the Wind Speed Profile in the Marine Atmospheric Boundary Layer   总被引：1，自引：1，他引：0  

Alfredo Peña  Sven-Erik Gryning  Charlotte B. Hasager 《Boundary-Layer Meteorology》2008,129(3):479-495

We present measurements from 2006 of the marine wind speed profile at a site located 18 km from the west coast of Denmark in the North Sea. Measurements from mast-mounted cup anemometers up to a height of 45 m are extended to 161 m using LiDAR observations. Atmospheric turbulent flux measurements performed in 2004 with a sonic anemometer are compared to a bulk Richardson number formulation of the atmospheric stability. This is used to classify the LiDAR/cup wind speed profiles into atmospheric stability classes. The observations are compared to a simplified model for the wind speed profile that accounts for the effect of the boundary-layer height. For unstable and neutral atmospheric conditions the boundary-layer height could be neglected, whereas for stable conditions it is comparable to the measuring heights and therefore essential to include. It is interesting to note that, although it is derived from a different physical approach, the simplified wind speed profile conforms to the traditional expressions of the surface layer when the effect of the boundary-layer height is neglected.  相似文献