DESTRUCTIVE EARTHQUAKES AND TSUNAMI WARNING SYSTEM     

Luis A. Mendes Victor  Maria Ana Viana Baptista  José Z. Simoes 《地学学报》1991,3(2):119-121

The Portuguese coast has been affected several times in the past by strong earthquakes that generated tsunamis severely damaging the city of Lisbon.
The most significant event known was the Lisbon earthquake of 1 November 1755. It is generally assumed that the location of this event was the Gorringe Bank region in the North Atlantic. This ridge, located 200 km south-west of the Portuguese shore, was also the location of the 28 February 1969 magnitude M_s= 7.9 earthquake (Fukao, 1973), that generated a tsunami of small amplitude clearly recorded at the tidal stations of the Portuguese south and south-west coasts.
The need to reduce the social and economic impact of an event of this type, greatly amplified by the urban concentration of coastal areas, led to the research project 'Destructive Earthquakes and Tsunami Warning System in SW Portugal'. This project, sponsored by the European Economic Community and the public Portuguese research funding agencies, has been conducted by the Geophysical Centre of the University of Lisbon, since April 1988.
The main targets of the project are:•the installation of a pilot warning system against tsunamis, based on two ocean bottom stations, comprising a 3 component seismometer and a bottom mounted pressure sensor, linked by cable to a surface buoy. This buoy is equipped with a data acquisition and data transmission system. Seismic and water level data will be collected on an almost real-time basis and will be transmitted to Lisbon via satellite;
•the refinement of existing geological models, in order to clarify the genesis of the bank and the seismic activity in this area;
•the installation of an adequate network of seismic monitoring stations in order to better locate off shore earthquakes (Fig. 1);
•the evaluation of seismic and tsunami risk around the Iberian Peninsula.  相似文献   

Construction,management and maintenance of embankments used for road and rail infrastructure: implications of weather induced pore water pressures     

Stephanie Glendinning  Paul Hughes  Peter Helm  Jonathan Chambers  Joao Mendes  David Gunn  Paul Wilkinson  Sebastien Uhlemann 《Acta Geotechnica》2014,9(5):799-816

Understanding the age and construction quality of embankments used for road and rail infrastructure is critical in the effective management and maintenance of our transport networks, worth £billions to the UK economy. This paper presents for the first time results from full-scale, carefully controlled experiments on a unique model embankment conducted over the 4-year period between 2008 and 2011. It combines point location and spatially distributed measurements of pore water pressures and water content with outputs from hydrological modelling to draw conclusions of significance to both ongoing research in this field and to the asset management practices of infrastructure owners. For researchers, the paper highlights the crucial importance of transient permeability and soil water retention behaviour of fill materials in controlling the magnitude and distribution of pore water pressure in response to climate and weather events. For practitioners, the work demonstrates that there are significant differences in pore water pressure behaviour across the embankment, which is influenced by construction-related issues such as compaction level, aspect and presence of a granular capping material. Permeability was also observed to vary across the embankment both spatially and with depth, being dependent on degree of saturation and macroscale effects, particularly within a ‘near surface zone’. It is proposed that this ‘near surface zone’ has a critical effect on embankment stability and should be the focus of both ongoing scientific research and inspection and monitoring as encompassed by asset management regimes.  相似文献   

Empirical seismic vulnerability analysis for masonry buildings based on school buildings survey in Iran     

Hamed Azizi-Bondarabadi  Nuno Mendes  Paulo B. Lourenço  Neda H. Sadeghi 《Bulletin of Earthquake Engineering》2016,14(11):3195-3229

School facilities in Iran, in particular masonry schools, have shown poor performance during past earthquakes and can be identified as one of the parts of the country’s infrastructure that is most vulnerable to earthquakes. Hence, in this paper a method to perform index-based damage assessment for brick masonry schools located in the province of Yazd, the central region of Iran, using a comprehensive database of school buildings, is proposed. The database was obtained from the field survey forms applied for each observed school to collect the features of and damage to the structure. The results of a vulnerability index method developed in Iran are employed as input data to obtain empirical fragility curves for the school inventory. The Macroseismic model and GNDT II level method are two empirical methods combined in this procedure. Finally, the procedure is verified using damage survey data obtained after recent earthquakes (1990 Manjil–Rudbar earthquake and 2003 Bam earthquake) that occurred in Iran.  相似文献   

Earth Rotation Observed by Very Long Baseline Interferometry and Ring Laser     

P. J. Mendes Cerveira  J. Boehm  H. Schuh  T. Kluegel  A. Velikoseltsev  K. U. Schreiber  A. Brzezinski 《Pure and Applied Geophysics》2009,166(8-9):1499-1517

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Morpho-tectonic analysis of the Azores Volcanic Plateau from a new bathymetric compilation of the area   总被引：13，自引：0，他引：13  

Lourenço  N.  Miranda  J.M.  Luis  J.F.  Ribeiro  A.  Victor  L.A. Mendes  Madeira  J.  Needham  H.D. 《Marine Geophysical Researches》1998,20(3):141-156

The existing studies of the Azores triple junction, although based on specific geological or geophysical data, largely rely upon morphological considerations. However, there is no systematic bathymetric coverage of this area, and the quality of the available bathymetric charts does not allow consistent morpho-structural analysis.In this work we present a new bathymetric grid elaborated with all the available data sources in an area comprised between 24° W to 32° W and 36° N to 41° N. The basic data set corresponds to the merge of NGDC data with new swath profiles. This new map, included as an Appendix, combined with other results from seismology and neotectonics, is the basis for the study of the morpho-structural pattern of the Azores area, the present day stress field and its implications on the current view of the Azores geodynamics.As a major result, we conclude that the Azores region is controlled by two sets of conjugated faults with 120° and 150° strikes that establish the framework for the onset of volcanism, expressing as linear volcanic ridges or as point source volcanism. This interaction develops what can be considered as the morphological signature of the Azores Spreading axis segmentation. We argue that the Azores domain, presently in a broad transtensional regime, is acting simultaneously as a ultra slow spreading centre and as a transfer zone between the MAR and the dextral Gloria Fault, as it accommodates the differential shear movement between the Eurasian and African plates.  相似文献   

Kinematics and Dynamics of Galaxies in Compact Groups for a sample of 31 groups     

P. Amram  C. Mendes de Oliveira  H. Plana  C. Balkowski  J. Boulesteix  C. Carignan 《Astrophysics and Space Science》2002,281(1-2):389-392

A long-term program based on Fabry-Perot Hα velocity field data of compact groups has been undertaken in order to analyse the kinematics of the compact group galaxies and the extent of their dark halos. The data are taken at the ESO and the CFH 3.6 m telescopes. The main goals of our project are: • To determine the evolutionary stages of the studied groups, • To search for tidal dwarf galaxy candidates in heavily interacting systems and • in combination with photometry available in the literature, to determine the Tully-Fisher relation for the group galaxies. The sample contains examples of groups at a variety of dynamical stages: from a false group that is in fact one single irregular galaxy with several star-forming blobs (e.g. H18) to a group whose members are strongly interacting and possibly forming tidal dwarf galaxies (e.g. H92) to a group in the final process of merging. We have so far identified five HCG classes: 1. merging groups2. strongly interacting, 3. weakly interacting, 4. non-groups, 5. single irregular galaxies. The ones which can be used in the TF studies are those in classes (2) and (3), for which comprehensive rotation curves can be derived. This revised version was published online in September 2006 with corrections to the Cover Date.  相似文献   

Atmospheric loading corrections at the observation level in VLBI analysis   总被引：3，自引：3，他引：0  

Johannes Boehm  Robert Heinkelmann  Paulo Jorge Mendes Cerveira  Andrea Pany  Harald Schuh 《Journal of Geodesy》2009,83(11):1107-1113

This paper investigates whether in very long baseline interferometry (VLBI) analysis atmospheric loading corrections should be applied a priori at the observation level or whether it is sufficient to correct for atmospheric loading effects a posteriori by adding constant values per session to the estimated station coordinates. Simulated observations at single stations corresponding to the precise point positioning approach of global navigation satellite systems show that the atmospheric loading effect can be fully recovered by a posteriori corrections, i.e., the height differences between both approaches stay well below 1 mm. However, real global VLBI network solutions with sessions from 1984 to 2008 reveal that the effect of neglected atmospheric loading corrections at the stations is distributed to the other stations in the network, thus resulting in station height differences between solutions with observation level and with a posteriori corrections which can be as large as 10 mm and a ‘damping’ effect of the corrections. As soon as the terrestrial reference frame and the corresponding coordinate time series are determined, it would be conceptually wrong to apply atmospheric loading corrections at the VLBI stations. We recommend the rigorous application of atmospheric loading corrections at the observation level to all stations of a VLBI network because the seven parameters for translation, rotation, and in particular the network-scale of VLBI networks are significantly affected.  相似文献   

Vegetation patterns in South America associated with rising CO2: uncertainties related to sea surface temperatures     

Marcos Paulo Santos Pereira  Marcos Heil Costa  Ana Cláudia Mendes Malhado 《Theoretical and Applied Climatology》2013,111(3-4):569-576

Spatially precise forecasts of the impacts of climate change on the distribution of major vegetation types are essential for the implementation of effective conservation and land use policy. However, existing studies frequently omit major sources of climate variability that can significantly increase the uncertainty of projections. In this study we demonstrate how different predictions for sea surface temperature (SST) for the first half of the twenty-first century increase the uncertainty associated with forecasts of the future distribution of major ecosystems in South America. This is demonstrated through a numerical experiment using a coupled climate–vegetation model (CCM3-IBIS) for IPCC emission scenario A2 that incorporates the SST data from ten different models. The study reveals an increasing uncertainty in the ability to forecast future vegetation patterns, such that by 2050 the simulation is unable to robustly forecast the vegetation cover in an area equivalent to 28 % in South America (5?×?10⁶ km²). The future of the central and northeastern regions of Brazil is especially uncertain, with outcomes, ranging from savanna, and open shrubland to grassland. Recognizing and managing such uncertainty should be a priority for decision makers.  相似文献   

Intragroup diffuse light in compact groups of galaxies – II. HCG 15, 35 and 51     

C. Da Rocha  B. L. Ziegler  C. Mendes de Oliveira 《Monthly notices of the Royal Astronomical Society》2008,388(3):1433-1443

This continuing study of intragroup light in compact groups of galaxies aims to establish new constraints to models of formation and evolution of galaxy groups, specially of compact groups, which are a key part in the evolution of larger structures, such as clusters. In this paper we present three additional groups (HCG 15, 35 and 51) using deep wide-field B - and R -band images observed with the LAICA camera at the 3.5-m telescope at the Calar Alto observatory (CAHA). This instrument provides us with very stable flat-fielding, a mandatory condition for reliably measuring intragroup diffuse light. The images were analysed with the ov_wav package, a wavelet technique that allows us to uncover the intragroup component in an unprecedented way. We have detected that 19, 15 and 26 per cent of the total light of HCG 15, 35 and 51, respectively, are in the diffuse component, with colours that are compatible with old stellar populations and with mean surface brightness that can be as low as 28.4 B mag arcsec⁻². Dynamical masses, crossing times and mass-to-light ratios were recalculated using the new group parameters. Also tidal features were analysed using the wavelet technique.  相似文献   

Determination of oxadiazon residues in the field treated soil with and without organic matter incorporated     

Kassio Ferreira Mendes  Marcelo Rodrigues dos Reis  Ana Beatriz Rocha de Jesus Passos  Miriam Hiroko Inoue  Antônio Alberto Silva  Daniel Valadão Silva 《Environmental Earth Sciences》2016,75(3):222

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