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Idalina Veludo Paula Teves-Costa Pierre-Yves Bard 《Bulletin of Earthquake Engineering》2013,11(2):423-453
Angra do Heroísmo, located in Terceira Island, is the main town of the Central Group of Azores Archipelago and it is classified as World Heritage by Unesco. The preservation of this patrimony, located inside a seismic region, includes the implementation of a policy to protect it against earthquakes. The development of credible damage scenarios could help this objective, as they can be used in prevention measures to minimize the impact of future earthquakes. Two methods were used for seismic damage estimation: the capacity spectrum method and a new method, based on the direct response of a 1D non-linear oscillator to simulate the building seismic performance. Both methods seem to overestimate the damages for the near sources, but this could be due to the empirical model used to estimate the input ground motion. Comparison with the damage observed after the January 1st, 1980 earthquake show a large discrepancy with an underestimation bias, which can be explained, mainly, by the difference of building performance and on the plausible hypothesis of 2D site effects. 相似文献
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The 23 April 1909 earthquake, with epicentre near Benavente (Portugal), was the largest crustal earthquake in the Iberian
Peninsula during the twentieth century (M
w = 6.0). Due to its importance, several studies were developed soon after its occurrence, in Portugal and in Spain. A perusal
of the different studies on the macroseismic field of this earthquake showed some discrepancies, in particular on the abnormal
patterns of the isoseismal curves in Spain. Besides, a complete list of intensity data points for the event is unavailable
at present. Seismic moment, focal mechanism and other earthquake parameters obtained from the instrumental records have been
recently reviewed and recalculated. Revision of the macroseismic field of this earthquake poses a unique opportunity to study
macroseismic propagation and local effects in central Iberian Peninsula. For this reasons, a search to collect new macroseismic
data for this earthquake has been carried out, and a re-evaluation of the whole set has been performed and it is presented
here. Special attention is paid to the observed low attenuation of the macroseismic effects, heterogeneous propagation and
the distortion introduced by local amplifications. Results of this study indicate, in general, an overestimation of the intensity
degrees previously assigned to this earthquake in Spain; also it illustrates how difficult it is to assign an intensity degree
to a large town, where local effects play an important role, and confirms the low attenuation of seismic propagation inside
the Iberian Peninsula from west and southwest to east and northeast. 相似文献
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Nikolaos Theodoulidis Giovanna Cultrera Valerio De Rubeis Fabrizio Cara Areti Panou Marco Pagani Paula Teves-Costa 《Bulletin of Earthquake Engineering》2008,6(1):109-140
In the framework of the SESAME project one of the tasks was the compilation of all available ambient noise measurements within urban environments affected by historical or/and recent strong earthquakes in Europe. The aim of such a task was to give an answer to the question; “How does horizontal-to-vertical ambient noise spectral ratio compare with damage in modern cities?”. For this purpose five European urban areas, namely, Angra do Heroismo (Portugal), Fabriano and Palermo (Italy), Thessaloniki and Kalamata (Greece) were selected for which spatial damage information was available either in terms of modified Mercalli intensity or in EMS98 damage grades. The geological setting of the examined sites as well as the causative earthquakes are satisfactorily known. Ambient noise recordings compiled for all examined sites have been homogeneously processed by a technique developed and agreed upon SESAME project. Using a standard multivariate statistical analysis, namely, factor analysis and canonical correlation, the horizontal-to-vertical ambient noise spectral ratio (HVNSR) is correlated with damage pattern observed within examined urban areas. Results show that, in some cases (Thessaloniki, Palermo), the HVNSR seems to be able to differentiate between areas previously shown to be associated with higher damage. In other cases however (Angra do Heroismo, Fabriano, Kalamata), the correlation is not statistically significant indicating thus the complex character of the parameters involved, implying that currently there is no a straightforward way that a value of HVNSR can correctly predict the extent to which a given region will be associated with increased damage. 相似文献
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Bertrand Guillier Kuvvet Atakan Jean-Luc Chatelain Jens Havskov Matthias Ohrnberger Fabrizio Cara Anne-Marie Duval Stratos Zacharopoulos Paula Teves-Costa The SESAME Team 《Bulletin of Earthquake Engineering》2008,6(1):3-31
For an optimal analysis of the H/V curve, it appears necessary to check the instrument signal to noise ratio in the studied
frequency band, to ensure that the signal from the ground noise is well above the internal noise. We assess the reliability
and accuracy of various digitizers, sensors and/or digitizer-sensor couples. Although this study is of general interest for
any kind of seismological study, we emphasize the influence of equipment on H/V analysis results. To display the impact of
the instrumental part on the H/V behavior, some series of tests have been carried out following a step-by-step procedure:
first, the digitizers have been tested in the lab (sensitivity, internal noise...), then the three components sensors, still
in the lab, and finally the usual user digitizers-sensors couple in lab and outdoors. In general, the digitizer characteristics,
verified during this test, correspond well to the manufacturer specifications, however, depending on the digitizer, the quality
of the digitized waveform can be very good to very poor, with variation from a channel to another channel (gain, time difference
etc.). It appears very clearly that digitizers need a warming up time before the recording to avoid problems in the low-frequency
range. Regarding the sensors, we recommend strongly to avoid the use of “classical” accelerometers (i.e., usual force balance
technology). The majority of tested seismometers (broadband and short period, even 4.5 Hz) can be used without problems from
0.4 to 25 Hz. In all cases, the instrumentation should be checked first to verify that it works well for the defined study
aim, but also to define its limit of use (frequency, sensitivity...). 相似文献
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F.?CarrilhoEmail author P.?Teves-Costa I.?Morais J.?Pagarete R.?Dias 《Pure and Applied Geophysics》2004,161(3):589-606
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Paula Teves-Costa Carlos S. Oliveira M. Luisa Senos 《Soil Dynamics and Earthquake Engineering》2007,27(11):986-999
During the Mw=6.9 January 1, 1980 earthquake in the Azores, the damage distribution in the town of Angra do Heroísmo, in Terceira Island, had a non-homogeneous spatial character. In order to understand the observed pattern of damage a microtremor survey was carried out, using ambient vibrations, and the data were analysed with the J-Sesame software, following the H/V Nakamura methodology. The results are in good agreement with the surface geology and they show a good correlation with the observed damages. Two building surveys were performed, in 1980 on damage evaluation and in 2000 on characterization of few building parameters. With all these elements (surface geology type, soil peak frequency, building type, number of stories and damage level) for 2111 buildings it was possible to perform several interparameter analysis, which enabled the identification of indicators that could be used to improve the damage estimation for future events. 相似文献
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Recovering seismic information contained in old analog records could increase our knowledge of seismic source characteristics and the seismicity of a region. This is particularly important in zones with low to moderate seismicity.To extract the available information, it is necessary to digitize the seismic records. This is not an easy task especially owing to the generally poor quality of the original records, with illegible or missing parts. However some exceptions were found in the records of a few seismological stations in Germany, Sweden and France.This paper presents an example of the recovering of source parameters and can be divided in two parts: the first one presents a simple semi-automatic technique for digitization of old analog seismic records, developed using commercial software on a PC; the second part describes the methodology of assessing the seismic moment, using empirical and theoretical relations, as well as the seismic source dimensions.The earthquake selected to illustrate this procedure is the 23 April 1909 Benavente (Portugal) earthquake. This earthquake occurred in the Lower Tagus Valley region and caused great destruction in the meizoseismal area. It is the biggest earthquake that occurred during this century in the central part of the country and its magnitude has been estimated between 6.6 and 7.6.The digitization procedure allowed the recovery of seismic information contained in old analog records, in particular, the seismic moment estimation. The results obtained indicated that 7.6 was a very high value for the magnitude of the 23 April 1909 earthquake, suggesting that the magnitude reported in the Portuguese catalogue is overestimated. The estimated moment magnitude is 6.0. 相似文献
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Soil characterization for seismic damage scenarios purposes: application to Angra do Heroísmo (Azores) 总被引：1，自引：1，他引：0
Angra do Heroismo, the main town of Terceira Island in the Azores Archipelago, was hit in 1980 by a 7.2 magnitude earthquake that caused great destruction in the central part of the town. Taking into consideration the high seismic hazard of the region and the cultural and social importance of Angra do Heroísmo, the elaboration of damage scenarios is of particular importance to implement measures for preserve and protect the town against future earthquakes. The first step is to perform microzonation studies in order to characterize the soil seismic behaviour. Taking into consideration the available geologic, geotechnical and geophysical information, a detailed soil characterization was performed based on the results from numerical modelling and the analysis of microtremor experimental measurements. Nine different soil profiles were identified, characterized and classified. Discussion on the detailed soil classification and the Eurocode 8 soil classification is presented. This study shows that even with an available code, microzonation studies must be developed in order to identify differences on soil behaviour inside the interested area. It shows also that the use of experimental measurements presents a great help on soil characterization. The obtained detailed classification will be used on the estimation of damage scenarios for Angra do Heroísmo. 相似文献
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