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1.
A statistical method to quantitatively assess the relative importance of unmodelled site and source effects on the observed variability (σ) in ground motions is presented. The method consists of analysis of variance (ANOVA) using the computed residuals with respect to an empirical ground-motion model for strong-motion records of various earthquakes recorded at a common set of stations. ANOVA divides the overall variance (σ 2) into the components due to site and source effects (respectively σ S 2 and σ E 2) not modelled by the ground-motion model plus the residual variance not explained by these effects (σ R 2). To test this procedure, four sets of observed strong-motion records: two from Italy (Umbria-Marche and Molise), one from the French Antilles and one from Turkey, are used. It is found that for the data from Italy, the vast majority of the observed variance is attributable to unmodelled site effects. In contrast, the variation in ground motions in the French Antilles and Turkey data is largely attributable, especially at short periods, to source effects not modelled by the ground-motion estimation equations used.  相似文献   

2.
Arias Intensity (Arias, MIT Press, Cambridge MA, pp 438–483, 1970) is an important measure of the strength of a ground motion, as it is able to simultaneously reflect multiple characteristics of the motion in question. Recently, the effectiveness of Arias Intensity as a predictor of the likelihood of damage to short-period structures has been demonstrated, reinforcing the utility of Arias Intensity for use in both structural and geotechnical applications. In light of this utility, Arias Intensity has begun to be considered as a ground-motion measure suitable for use in probabilistic seismic hazard analysis (PSHA) and earthquake loss estimation. It is therefore timely to develop predictive equations for this ground-motion measure. In this study, a suite of four predictive equations, each using a different functional form, is derived for the prediction of Arias Intensity from crustal earthquakes in New Zealand. The provision of a suite of models is included to allow for epistemic uncertainty to be considered within a PSHA framework. Coefficients are presented for four different horizontal-component definitions for each of the four models. The ground-motion dataset for which the equations are derived include records from New Zealand crustal earthquakes as well as near-field records from worldwide crustal earthquakes. The predictive equations may be used to estimate Arias Intensity for moment magnitudes between 5.1 and 7.5 and for distances (both rjb and rrup) up to 300 km.  相似文献   

3.
地震危险性概率分析(PSHA)是目前最广泛应用于地震灾害与风险性评估的方法。然而它在计算中却存在着一个错误:把强地面运动衰减关系(一个函数)的条件超越概率等同于强地面运动误差(一个变量)的超越概率。这个错误导致了运用强地面运动误差(空间分布特征)去外推强地面运动的发生(时间分布特征)或称之为遍历性假设,同时也造成了对PSHA理解和应用上的困难。本文推导出新的灾害计算方法(称之为KY-PSHA)来纠正这种错误。  相似文献   

4.
We derive S-wave attenuation characteristics, earthquake source parameters and site amplification functions at seismic stations used for earthquake early warning in the Irpinia–Basilicata region, using non-parametric spectral inversion of seismograms from 49 local events with M L = 1.5–3.1. We obtain relatively low Q values (Q 0 = 28 at a frequency of 1 Hz) in conjunction with a strong frequency-dependence (close to linear). The source spectra can be satisfactorily modeled using the omega-square model, with stress drops ranging between 0.01–2 MPa, and in the narrow magnitude range available for analysis, the source spectra seem to scale self-similarly. The local magnitude M L shows a linear correlation with moment magnitude M W, however with a systematic underestimation by about 0.5-magnitude units. The results obtained in this work provide important insights into the ground-motion characteristics that are required for appropriate seismic hazard assessment and are of practical relevance for a suite of applications, such as the calibration of ground-motion prediction equations or the correction for site amplification in earthquake early warning and rapid calculation of shake-maps for seismic emergency management.  相似文献   

5.
Scherbaum et al. [(2004) Bull Seismolo Soc Am 94(6): 2164–2185] proposed a likelihood-based approach to select and rank ground-motion models for seismic hazard analysis in regions of low-seismicity. The results of their analysis were first used within the PEGASOS project [Abrahamson et al. (2002), In Proceedings of the 12 ECEE, London, 2002, Paper no. 633] so far the only application of a probabilistic seismic hazard analysis (PSHA) in Europe which was based on a SSHAC Level 4 procedure [(Budnitz et al. 1997, Recommendations for PSHA: guidance on uncertainty and use of experts. No. NUREG/CR-6372-V1). The outcome of this project have generated considerable discussion (Klügel 2005, Eng Geol 78:285–307, 2005b) Eng Geol 78: 285–307, (2005c) Eng Geol 82: 79–85 Musson et al. (2005) Eng Geol 82(1): 43–55]; Budnitz et al. (2005), Eng Geol 78(3–4): 285–307], a central part of which is related to the issue of ground-motion model selection and ranking. Since at the time of the study by Scherbaum et al. [(2004.) Bull Seismolo Soc Am 94(6): 2164–2185], only records from one earthquake were available for the study area, here we test the stability of their results using more recent data. Increasing the data set from 12 records of one earthquake in Scherbaum et al. [(2004) Bull Seismolo Soc Am 94(6): 2164–2185] to 61 records of 5 earthquakes, which have mainly occurred since the publication of the original study, does not change the set of the three top-ranked ground-motion models [Abrahamson and Silva (1997) Seismolo Res Latt 68(1): 94–127; Lussou et al. (2001) J Earthquake Eng 5(1):13–33; Berge-Thierry et al. (2003) Bull Seismolog Soc Am 95(2): 377–389. Only for the lower-ranked models do we obtain modifications in the ranking order. Furthermore, the records from the Waldkirch earthquake (Dec, 5th, 2004, M w = 4.9) enabled us to develop a new stochastic model parameter set for the application of Campbell’s [(2003) Bull Seismolo Soc Am 93(3): 1012–1033] hybrid empirical model to SW Germany and neighbouring regions.  相似文献   

6.
The seismic microzonation of the Bengal Basin, Haldia region, India is carried out using the Analytical Hierarchy Process (AHP) on the Geographic Information System (GIS). Three themes are used for the seismic microzonation, namely Peak Ground Acceleration (PGA), predominant frequency and elevation map. An analysis of the maximum magnitude (m max) and the b value is carried out after preparing the earthquake catalogue from various sources. On the basis of the tectonic set up and seismicity of the region, five seismic zones are delineated which can be a threat to Haldia. They are broadly classified as Zone 1: Arakan-Yoma Zone (AYZ), Zone 2: Himalayan Zone (HZ), Zone 3: Shillong Plateau Zone (SPZ), Zone 4: Bay of Bengal Zone (BBZ) and Zone 5: Shield Zone (SZ). The m max for Zones 1, 2, 3, 4 and 5 are 8.30 ± 0.51, 9.09 ± 0.58, 9.20 ± 0.51, 6.62 ± 0.43 and 6.61 ± 0.43, respectively. The PGA value is computed for Haldia following the attenuation relationship taking the m max of each source zone. The expected PGA at Haldia varies from 0.09–0.19 g. The predominant frequency of Haldia is also calculated using the H/V ratio with a frequency ranging from 0.1–3.0 Hz. The elevation map of Haldia is also generated using the Shuttle Radar Topography Mission (STRM) data. A first-order seismic microzonation map of Haldia is prepared in which four zones of hazard have been broadly classified for Haldia as very high seismic hazard zone, high seismic hazard zone, moderate seismic hazard zone and less seismic hazard zone. The very high seismic hazard zone is observed along the southern part of Haldia where there are major industrial and port facilities. The PGA for the four hazard zones are: 0.09–0.13 g for low hazard zone, > 0.13–0.15 g for moderate hazard zone, > 0.15–0.16 g for high hazard zone and > 0.16–0.19 g for very high hazard zone.  相似文献   

7.
Ａｌｉｇｎｍｅｎｔｓｉｌｋｗｏｒｍｓａｓｓｅｉｓｍｉｃａｎｉｍａｌａｎｏｍａｌｏｕｓｂｅｈａｖｉｏｒ（ＳＡＡＢ）ａｎｄｅｌｅｃｔｒｏｍａｇｎｅｔｉｃｍｏｄｅｌｏｆａｆａｕｌｔ：ａｔｈｅｏｒｙａｎｄｌａｂｏｒａｔｏｒｙｅｘｐｅｒｉｍｅｎｔＭＯＴＯ...  相似文献   

8.
Probabilistic seismic hazard for Mainland Portugal was re-evaluated in order to perform its disaggregation. Seismic hazard was disaggregated considering different spaces of random variables, namely, univariate conditional hazard distributions of M (magnitude), R (source-to-site distance) and ε (deviation of ground motion to the median value predicted by an attenuation model), bivariate conditional hazard distributions of M–R and X–Y (seismic source latitude and longitude) or multivariate conditional hazard distributions of M–R–ε and M–(X–Y)–ε. The main objective of the present work was achieved, as it was possible, based on the modal values of the above mentioned distributions, to characterize the scenarios that dominate some seismic hazard levels of the 278 Mainland Portuguese counties. In addition, results of 4D disaggregation analysis, in M–(X–Y)–ε, pointed out the existence of one geographic location shared by the dominant scenario of most analyzed counties, especially for hazard levels correspondent to high return periods. Those dominant scenarios are located offshore at a distance of approximately 70 km WSW of S. Vicente cape. On the other hand, the lower the return period the higher is the number of modal scenarios in the neighbourhood of the analyzed site. One may conclude that modal scenarios reproduce hazard target values in each site with great accuracy enabling the applications derived from those scenarios (e.g. loss evaluation) to be associated to a hazard level exceedance probability.  相似文献   

9.
Peak ground motion predictions in India: an appraisal for rock sites   总被引：1，自引：0，他引：1  
Proper selection and ranking of Ground Motion Prediction Equations (GMPEs) is critical for successful logic-tree implementation in probabilistic seismic hazard analysis. The present study explores this issue in predicting peak ground accelerations at the rock sites in India. Macroseismic intensity data complemented with limited strong ground-motion recordings are used for the purpose. The findings corroborate the possible conformity between the GMPEs developed for tectonically active shallow crust across the globe. On the other hand, the relevant GMPEs in the intraplate regions cluster into two different groups with the equations of lower ranks catering to higher ground motions. The earthquakes in the subduction zones have significant regional implications. However, affinity in the ground-motion attenuations between the major interface events (M W > 7.4) in Andaman-Nicobar, Japan and Cascadia, respectively, is noted. This can be also observed for the intraslab events in the Hindukush and Taiwan respectively. Overall, we do not observe any significant advantage with the equations developed using the regional data. These findings are expected to be useful in probabilistic seismic hazard analysis across the study region.  相似文献   

10.
The first ground-motion prediction equation derived from European and Middle Eastern strong-motion data was published more than 30 years ago; since then strong-motion networks and the resulting databank of accelerograms in the region have expanded significantly. Many equations for the prediction of peak ground-motion parameters and response spectral ordinates have been published in recent years both for the entire Euro-Mediterranean and Middle Eastern region as well as for individual countries within this region. Comparisons among empirical ground-motion models for these parameters, developed using large regional datasets, do not support the hypothesis of there being significant differences in earthquake ground-motions from one area of crustal seismicity to another. However, there are certain regions within Europe—affected by different tectonic regimes—for which the existing pan-European equations may not be applicable. The most recent European equations make it possible to now implement overdue modifications to the presentation of seismic design actions in Eurocode 8 that allow an improved approximation to the target uniform hazard spectrum (UHS). Using these recent equations, this study outlines a new approach via which an approximation to the UHS may be constructed using hazard maps calculated for peak ground velocity and the corner period T D in addition to the maps for peak ground acceleration that underpin the current stipulations of Eurocode 8.  相似文献   

11.
应用“固结问题和布辛涅斯克问题解”,计算了丹江水库水位在130m和157m两种情况下,库区基岩体深度分别为1、3、5、7、9、11、13和15km时的水压应力场、变形场和超孔隙水压力场。结果表明,σ_1、σ_3和τ_(max)在库中心位置最大,库岸边较小;同时σ_1和σ_3在库中心均显压性,而在库岸边σ_3显张性;垂直位移在库中心最大(7cm),而水平位移在库岸边最大(0.5cm);超孔隙水压力一般在库中心深水区库基下3—9km处最大,库岸边和浅水区较小;体应变一般在库中心位置形成压缩区,而在库岸边则形成拉伸应变区并同时向四周扩展,与诱发地震震中分布相一致。  相似文献   

12.
ＥｓｔｉｍａｔｉｏｎｏｆｓｅｉｓｍｉｃｓｔｒｅｓｄｒｏｐｆｒｏｍｔｈｅｐｅａｋｖｅｌｏｃｉｔｙｏｆｇｒｏｕｎｄｍｏｔｉｏｎＪＩＡＺＨＥＮＧＱＩＮ（秦嘉政）ＺＵＹＩＮＬＩＵ（刘祖荫）ＸＩＡＯＤＯＮＧＱＩＡＮ（钱晓东）ＱＩＮＧＹＩＮＸＩＥ（谢庆...  相似文献   

13.
Empirical recordings of ground motions featuring large amplitudes of acceleration or velocity play a key role in defining the maximum levels of ground motion required for the design of engineering projects, in view of their potentially very destructive nature. They also provide valuable insights as to the nature of the tails of the ground-motion distribution. The present paper reviews the interpretations put forward for a dataset of recordings selected for their large value of PGA (?1 g) or PGV (?100 cm/s), and attempts to classify causative physical processes according to a uniform nomenclature. The aim of the study is to identify to what extent large-amplitude ground motions are predictable, by separating scenarios that could generally be encountered and foreseen using current knowledge of the processes involved in earthquake ground-motion generation and propagation, such as particular features of the recording site, from occurrences that are related to unforeseeable characteristics of the source and path.  相似文献   

14.
ＴｈｅｒｅｇｉｏｎａｌｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｓｅｉｓｍｉｃａｃｔｉｖｉｔｙｉｎＣｈｉｎａＺｈｅｎ－ＬｉａｎｇＳＨＩ，ＪｉａｎＷＡＮＧａｎｄＸｉａｏ－ＤｏｎｇＺＨＡＮＧ（时振梁，王健，张晓东）（ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｐｈｙｓｉｃｓ，Ｓ...  相似文献   

15.
Starting from the classical empirical magnitude-energy relationships, in this article, the derivation of the modern scales for moment magnitude M w and energy magnitude M e is outlined and critically discussed. The formulas for M w and M e calculation are presented in a way that reveals, besides the contributions of the physically defined measurement parameters seismic moment M 0 and radiated seismic energy E S, the role of the constants in the classical Gutenberg–Richter magnitude–energy relationship. Further, it is shown that M w and M e are linked via the parameter Θ = log(E S/M 0), and the formula for M e can be written as M e = M w + (Θ + 4.7)/1.5. This relationship directly links M e with M w via their common scaling to classical magnitudes and, at the same time, highlights the reason why M w and M e can significantly differ. In fact, Θ is assumed to be constant when calculating M w. However, variations over three to four orders of magnitude in stress drop Δσ (as well as related variations in rupture velocity V R and seismic wave radiation efficiency η R) are responsible for the large variability of actual Θ values of earthquakes. As a result, for the same earthquake, M e may sometimes differ by more than one magnitude unit from M w. Such a difference is highly relevant when assessing the actual damage potential associated with a given earthquake, because it expresses rather different static and dynamic source properties. While M w is most appropriate for estimating the earthquake size (i.e., the product of rupture area times average displacement) and thus the potential tsunami hazard posed by strong and great earthquakes in marine environs, M e is more suitable than M w for assessing the potential hazard of damage due to strong ground shaking, i.e., the earthquake strength. Therefore, whenever possible, these two magnitudes should be both independently determined and jointly considered. Usually, only M w is taken as a unified magnitude in many seismological applications (ShakeMap, seismic hazard studies, etc.) since procedures to calculate it are well developed and accepted to be stable with small uncertainty. For many reasons, procedures for E S and M e calculation are affected by a larger uncertainty and are currently not yet available for all global earthquakes. Thus, despite the physical importance of E S in characterizing the seismic source, the use of M e has been limited so far to the detriment of quicker and more complete rough estimates of both earthquake size and strength and their causal relationships. Further studies are needed to improve E S estimations in order to allow M e to be extensively used as an important complement to M w in common seismological practice and its applications.  相似文献   

16.
Local site conditions can significantly influence the characteristics of seismic ground motions. In this study, site response analyses using one-dimensional linear elastic (LE), equivalent-linear (EQL) and nonlinear (NL) approaches are performed at different seismic hazard levels of Singapore. Two seismic stations, namely, the KAP and BES stations located at soft soil sites, are selected from the national network of Singapore. Firstly, site response estimates using the LE, EQL (SHAKE04) and NL (DEEPSOIL) approaches are compared with the borehole recordings. Results show favorable matches between the predictions and the observations at the KAP site, while under-predictions are observed for all the three site effect approaches at the BES site. Secondly, the applicability of the LE, EQL and NL models is examined at different hazard levels of Singapore. It is found that for the hazard level at a return period of 475 years, the computed maximum strain (γmax) is 0.06% and then the EQL model can provide accurate site response predictions. However, for the hazard level at a return period of 2475 years, the calculated γmax is larger than 2%, resulting in notable differences in the predictions of different site response models. This study highlights the importance of site effects in seismic hazard analysis of Singapore.  相似文献   

17.
In order to empirically obtain the scaling relationships for the high-frequency ground motion in the Western Alps (NW Italy), regressions are carried out on more than 7500 seismograms from 957 regional earthquakes. The waveforms were selected from the database of 6 three-component stations of the RSNI (Regional Seismic network of Northwestern Italy). The events, M W ranging between 1.2 and 4.8, were recorded within a hypocentral distance of 200 km during the time period: 1996–2001. The peak ground velocities are measured in selected narrow-frequency bands, between 0.5 and 14 Hz. Results are presented in terms of a regional attenuation function for the vertical ground motion, a set of vertical excitation terms at the reference station STV2 (hard-rock), and a set of site terms (vertical and horizontal), all relative to the vertical component of station STV2.The regional propagation of the ground motion is modeled after quantifying the expected duration of the seismic motion as a function of frequency and hypocentral distance. A simple functional form is used to take into account both the geometrical and the anelastic attenuation: a multi-variable grid search yielded a quality factor Q(f) = 310f 0.20, together with a quadri-linear geometrical spreading at low frequency. A simpler, bi-linear geometrical spreading seems to be more appropriate at higher frequencies (f > 1.0 Hz). Excitation terms are matched by using a Brune spectral model with variable, magnitude-dependent stress drop: at M w 4.8, we used Δσ = 50 MPa. A regional distance-independent attenuation parameter is obtained (κ0 = 0.012 s) by modelling the average spectral decay at high frequency of small earthquakes.In order to predict the absolute levels of ground shaking in the region, the excitation/attenuation model is used through the Random Vibration Theory (RVT) with a stochastic point-source model. The expected peak-ground accelerations (PGA) are compared with the ones derived by Ambraseys et al. (1996) for the Mediterranean region and by Sabetta and Pugliese (1996) for the Italian territory.  相似文献   

18.
An endeavor is made to compute peak ground horizontal accelerations at bedrock level in the Delhi region due to the seismogenic sources present around Delhi. The entire area is divided into six seismogenic sources for which seismic hazard analysis is carried out using the complete and extreme part of the seismicity data. Maximum likelihood estimates of hazard parameters viz., seismic activity rate , b value and maximum probable earthquake M max are made for each zone. The return periods and the probabilities of occurrence of various magnitudes for return periods of 50, 100 and 1000 years are also computed for each zone. The peak ground acceleration (PGA) values for 20% exceedance in 50 years are then computed for the Delhi region from each zone. The maximum PGA value considering all the zones is 0.34 g, which is due to the Mathura fault zone. The seismogenic zones V and VI, i.e., Mathura fault zone and the Sohna fault zone are observed to be contributing maximum PGA values in the Delhi region governing the isoacceleration contours computed for the region. The seismic zonation map for the PGA values at the bedrock level is obtained for the Delhi region. This can be used directly as input for the microzonation of ground motion at the surface by incorporating the local site conditions.  相似文献   

19.
A comprehensive study is presented for empirical seismic vulnerability assessment of typical structural types, representative of the building stock of Southern Europe, based on a large set of damage statistics. The observational database was obtained from post-earthquake surveys carried out in the area struck by the September 7, 1999 Athens earthquake. After analysis of the collected observational data, a unified damage database has been created which comprises 180,945 damaged buildings from/after the near-field area of the earthquake. The damaged buildings are classified in specific structural types, according to the materials, seismic codes and construction techniques in Southern Europe. The seismic demand is described in terms of both the regional macroseismic intensity and the ratio αg/ao, where αg is the maximum peak ground acceleration (PGA) of the earthquake event and ao is the unique value PGA that characterizes each municipality shown on the Greek hazard map. The relative and cumulative frequencies of the different damage states for each structural type and each intensity level are computed in terms of damage ratio. Damage probability matrices (DPMs) and vulnerability curves are obtained for specific structural types. A comparison analysis is fulfilled between the produced and the existing vulnerability models.  相似文献   

20.
Fourier-amplitude spectrum is one of the most important parameters describing earthquake ground motion, and it is widely used for strong ground motion prediction and seismic hazard estimation. The relationships between Fourier-acceleration spectra, earthquake magnitude and distance were analysed for different seismic regions (the Caucasus and Taiwan island) on the basis of ground motion recordings of small to moderate (3.5≤ML≤6.5) earthquakes. It has been found that the acceleration spectra of the most significant part of the records, starting from S-wave arrival, can be modelled accurately by the Brune's “ω-squared” point-source model. Parameters of the model are found to be region-dependent. Peak ground accelerations and response spectra for condition of rock sites were calculated using stochastic simulation technique and obtained models of source spectra. The modelled ground-motion parameters are compared with those predicted by recent empirical attenuation relationship for California.  相似文献   

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