Seismic Ground Motion Hazard Assessment at a Site near a Segmented Subduction Zone: The Roseau Dam, Saint Lucia, West Indies

1994 ◽  
Vol 10 (2) ◽  
pp. 259-292 ◽  
Author(s):  
W. P. Aspinall ◽  
J. B. Shepherd ◽  
G. Woo ◽  
A. Wightman ◽  
K. C. Rowley ◽  
...  

The seismic hazard at the site of a new dam in Saint Lucia, West Indies, is evaluated probabilistically for engineering design purposes. The assessment takes advantage of recent high quality regional seismological data, reappraised older instrumental catalogues and current tectonic interpretations. Saint Lucia stands at a position in the Lesser Antilles island arc where two distinct, seismically active, subduction zones appear to converge at different depths. As a result, the seismic hazard is critically dependent on site position relative to the boundaries of these major source zones, which each exhibit different activity rates. The ground motion hazard at the damsite is computed using the probabilistic logic-tree program PRISK, which accepts weighted input parameter distributions and is also able to model complex source geometries such as those needed to realistically represent a subduction zone. At an exceedance probability of 2×10−3 per annum, the expected peak ground acceleration on rock at the site is 0.27g, and the expected peak ground velocity is 12.9 cm/sec. At an exceedance probability of 10−4 per annum, the expected peak ground acceleration on rock at the site is 0.51g, and the expected peak ground velocity is 29.1 cm/sec. The major contributor to the seismic hazard is a large magnitude earthquake occurring in the northern segment of the Lesser Antilles subduction zone. Sensitivity tests show that the results are stable in the face of rational variations in the seismicity parameters but the hazard values are dependent on the choice of attenuation relationship which, in the absence of local information, has to be adopted from other subduction zone areas. The PGA obtained in this study is markedly higher than the value suggested in current regional code recommendations.

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Zhenming Wang ◽  
David T. Butler ◽  
Edward W. Woolery ◽  
Lanmin Wang

A scenario seismic hazard analysis was performed for the city of Tianshui. The scenario hazard analysis utilized the best available geologic and seismological information as well as composite source model (i.e., ground motion simulation) to derive ground motion hazards in terms of acceleration time histories, peak values (e.g., peak ground acceleration and peak ground velocity), and response spectra. This study confirms that Tianshui is facing significant seismic hazard, and certain mitigation measures, such as better seismic design for buildings and other structures, should be developed and implemented. This study shows that PGA of 0.3 g (equivalent to Chinese intensity VIII) should be considered for seismic design of general building and PGA of 0.4 g (equivalent to Chinese intensity IX) for seismic design of critical facility in Tianshui.


Author(s):  
A. K. Ghosh ◽  
H. S. Kushwaha

The various uncertainties and randomness associated with the occurrence of earthquakes and the consequences of their effects on the NPP components and structures call for a probabilistic seismic risk assessment (PSRA). However, traditionally, the seismic design basis ground motion has been specified by normalised response spectral shapes and peak ground acceleration (PGA). The mean recurrence interval (MRI) used to be computed for PGA only. The present work develops uniform hazard response spectra i.e. spectra having the same MRI at all frequencies for Kakrapar Atomic Power Station site. Sensitivity of the results to the changes in various parameters has also been presented. These results determine the seismic hazard at the given site and the associated uncertainties. The paper also presents some results of the seismic fragility for an existing containment structure. The various parameters that could affect the seismic structural response include material strength of concrete, structural damping available within the structure and the normalized ground motion response spectral shape. Based on this limited case study the seismic fragility of the structure is developed. The results are presented as families of conditional probability curves plotted against the peak ground acceleration (PGA). The procedure adopted incorporates the various randomness and uncertainty associated with the parameters under consideration.


2017 ◽  
Vol 17 (4B) ◽  
pp. 82-95
Author(s):  
Nguyen Anh Duong ◽  
Pham Dinh Nguyen ◽  
Vu Minh Tuan ◽  
Bui Van Duan ◽  
Nguyen Thuy Linh

In this study, we have carried out the probabilistic seismic hazard analysis in Hanoi based on the latest seismotectonic data. The seismic hazard map shows peak ground acceleration values on rock corresponding to the 10% probability of exceedance in a 50-year time period (approximately return periods of 500 years). The calculated results reveal that the maximum ground acceleration can occur on rock in Hanoi is about 0.13 g corresponding to the shaking intensity level of VIII on the MSK-64 scale. The ground motion values calculated on rock vary according to the local site conditions. We have evaluated and corrected the local site effects on ground motion in Ha Dong district, Hanoi by using microtremor and borehole data. The Nakamura’s H/V spectral ratio method has been applied to establish a map of ground dominant periods in Ha Dong with a TS range of 0.6 - 1.2 seconds. The relatively high values of periods indicate that Ha Dong has soft soil and thick Quaternary sediments. The sediment thickness in Ha Dong is calculated to vary between 30 - 75 m based on ground dominant periods and shear wave velocity VS30 = 171 - 254 m/s. The results of local site effect on ground motion show that the 500-year return period peak ground acceleration in Ha Dong ranges from 0.13 g to 0.17 g. It is once again asserted that the seismic hazard in Hanoi is a matter of great concern, due not only to the relatively high ground acceleration, but also to the seismic characteristics of soil (low shear wave velocity, ground dominant period of approximately 1 second).


2020 ◽  
Author(s):  
Guan-Yi Song ◽  
Yih-Min Wu

<p>The relationships between ground motion parameters (including peak ground acceleration, PGA; peak ground velocity, PGV) and building damages are crucial to estimate the possible seismic losses for future destructive earthquakes. One such relationship had been established based on the 1999 Chi-Chi earthquake (Mw=7.6). Since 2010, a new assessment system of seismic damaged buildings had been adopted in Taiwan. Damaged buildings are now classified into two categories, yellow-tagged buildings are amendable and red-tagged buildings may need to rebuild. Our main goal is to renew the relationship to better reflect the current status in Taiwan, both in the buildings and assessment system. 2016 Meinong earthquake (Mw=6.4) caused the most damaging buildings in Taiwan since 1999 Chi-Chi earthquake. It’s an opportunity to combine ground motion data with building assessments for the new regression relationship. From the results, we find out that in the Meinong earthquake, the PGA seems to possess a higher correlation to the building damages, contrary to the previous studies. Further investigation suggests that it may be due to the biased sample size to the damaged buildings, that is, most of the damaged buildings tend to be lower.</p><p>Keywords: Hazard analysis, Peak ground acceleration, Peak ground velocity, Seismic damage assessment</p>


2010 ◽  
Vol 10 (1) ◽  
pp. 25-39 ◽  
Author(s):  
G-A. Tselentis ◽  
L. Danciu

Abstract. Seismic hazard assessment represents a basic tool for rational planning and designing in seismic prone areas. In the present study, a probabilistic seismic hazard assessment in terms of peak ground acceleration, peak ground velocity, Arias intensity and cumulative absolute velocity computed with a 0.05 g acceleration threshold, has been carried out for Greece. The output of the hazard computation produced probabilistic hazard maps for all the above parameters estimated for a fixed return period of 475 years. From these maps the estimated values are reported for 52 Greek municipalities. Additionally, we have obtained a set of probabilistic maps of engineering significance: a probabilistic macroseismic intensity map, depicting the Modified Mercalli Intensity scale obtained from the estimated peak ground velocity and a probabilistic seismic-landslide map based on a simplified conversion of the estimated Arias intensity and peak ground acceleration into Newmark's displacement.


Author(s):  
Г.П. Ганапатхи ◽  
В.Б. Заалишвили ◽  
Д.А. Мельков ◽  
В.Б. Свалова ◽  
А.В. Николаев

В работе представлен инструментарий в виде ГИС-технологий для составления карты сейсмического микрорайонирования. Рассмотрены методы и способы индийской и российской практики сейсмического микрорайонирования Реализована компиляция исходных данных в оперативную экспресс ГИС-методику. Построена карта сейсмического микрорайонирования первого уровня для города Ченнаи (Индия) с использованием ГИС-платформы на основе использования специфических информационных слоев в виде пикового ускорения грунта (PGA), скорости поперечной волны, геологического строения территории, уровня грунтовых вод и глубины кровли подстилающих коренных пород. Пиковое ускорение для сейсмических источников оценивалось на основе отношения затухания. При этом максимальное ускорение PGA для Ченнаи составило 0,176 g, а для Владикавказа – 0,2 g (для вероятности превышения 5%). Анализ сейсмической опасности включал матрицы данных (дискретные наборы данных из разных тем были преобразованы в сетки) для расчета окончательной матрицы сейсмической опасности путем интеграции и анализа веса исходных тематических слоев. Город Ченнай в процессе исследования был разделен на три обширные зоны: высокой, умеренной и низкой сейсмической опасности. Карта сейсмического микрорайонирования города Владикавказа была представлена в единицах шкалы MSK-64 и единицах ускорения. В обоих рассмотренных подходах скорости поперечных волн были одной из основных инструментальных основ для соответствующих расчетов. Используя в качестве исходных данных сценариев синтезированные расчетные записи с учетом характеристик неисправностей, учитывается трансформация исходных акселерограмм, обусловленных свойствами почвы на территории. In the paper GIS approach for seismic microzonation map compilation is presented. Approaches of Indian and Russian seismic microzonation practice are considered and compilated in express GIS technique. A first level seismic microzonation map of Chennai city has been produced with a GIS platform using the themes, viz, Peak Ground Acceleration (PGA), Shear wave velocity at 3 m, Geology, Ground water fluctuation and bed rock depth. The peak ground acceleration for these seismic sources were estimated based on the attenuation relationship and the maximum PGA for Chennai is 0.176 g and for Vladikavkaz 0.2 g (for 5% exceedance probability). The seismic microzonation analysis involved grid datasets (the discrete datasets from different themes were converted to grids) to compute the final seismic hazard grid through integration and weightage analysis of the source themes. The Chennai city has been classified into three broad zones, viz, High, Moderate and Low Seismic Hazard. Vladikavkaz city microzonation map was presented in MSK-64 scale. In both approaches shear wave velocities was one of the basic instrumental data. Using as initial data of the scenario synthesized records, taking into account the characteristics of faults, takes into account the transformation of the original accelerograms stipulated by soil properties of the territory.


1995 ◽  
Vol 85 (5) ◽  
pp. 1343-1358
Author(s):  
Gilbert L. Molas ◽  
Fumio Yamazaki

Abstract New attenuation equations for peak ground acceleration and velocity for Japan are developed. The equations are derived using extensive data recorded by the new JMA-87-type accelerometers, which do not require instrumental corrections that the older SMAC-type accelerometers do. Earthquakes with depths up to 200 km are used to make the equation applicable to subduction zone regions, which are common in Japan. Effects of depth and local site on the attenuation are considered simultaneously with the distance dependence and magnitude dependence using a two-stage regression procedure to separate the magnitude dependence from the distance dependence. Since the resulting normal equations become singular, an iterative partial regression algorithm is proposed. It is found that for the same magnitude and distance, peak ground motion increases as depth increases. The variation of the station coefficients with respect to the corresponding soil-type classification is quite wide. The station coefficients for the peak ground acceleration are found to be weakly correlated with the general soil classification, while a stronger correlation was found for the peak ground velocity. The resulting attenuation relations are given by log10PGA=0.206+0.477MJ−log10r−0.00144r−0.00144r+0.00311h+cia,log10PGV=−1.769+0.628MJ−log10r−0.00130r−0.00144r+0.00222h+civ, where PGA (cm/sec2) and PGV (cm/sec) are the larger of the peak accelerations and velocities from two horizontal components, MJ is the JMA magnitude, r is the closest distance to the fault rupture, h is the depth, and ci is the station coefficient of the recording station. The mean of the coefficients of the JMA stations is given by ci = 0.


Author(s):  
Ellen M. Rathje ◽  
Gokhan Saygili

The evaluation of earthquake-induced landslides in natural slopes is often based on an estimate of the permanent sliding displacement due to earthquake shaking. Current procedures for estimating sliding displacement do not rigorously account for the significant uncertainties present in the analysis. This paper presents a probabilistic framework for computing the annual rate of exceedance of different levels of displacement such that a hazard curve for sliding displacement can be developed. The analysis incorporates the uncertainties in the prediction of earthquake ground shaking, in the prediction of sliding displacement, and in the assessment of soil properties. Predictive models for sliding displacement that are appropriate for the probabilistic framework are presented. These models include a scalar model that predicts sliding displacement in terms of a single ground motion parameter (peak ground acceleration) and the earthquake magnitude, as well as a vector model that incorporates two ground motion parameters (peak ground acceleration and peak ground velocity). The addition of a second ground motion parameter results in a significant reduction in the standard deviation of the sliding displacement prediction. Comparisons are made between displacement hazard curves developed from the current scalar and vector models and previously developed scalar models that do not include earthquake magnitude. Additionally, an approximation to the vector hazard assessment is presented and compared with the rigorous vector approach. Finally, the inclusion of the soil property uncertainty is shown to increase the mean hazard at a site.


2020 ◽  
Author(s):  
Vasily Pavlenko

<p>The problem is considered of unrealistic ground motion estimates, which arise when the Cornell–McGuire method is used to estimate the seismic hazard for extremely low annual probabilities of exceedance. This problem stems from using the normal distribution in the modelling of the variability of the logarithm of ground motion parameters. In this study, the statistical properties of the logarithm of peak ground acceleration (PGA) are analysed by using the database of the strong-motion seismograph networks of Japan. The normal distribution and the generalised extreme value distribution (GEVD) models were considered in the analysis, with the preferred model being selected based on statistical criteria. The results indicate that the GEVD was a more appropriate model in eleven out of twelve instances. The estimates of the shape parameter of the GEVD were negative in every instance, indicating the presence of a finite upper bound of PGA. Therefore, the GEVD provides a model that is more realistic for the scatter of the logarithm of PGA, and the application of this model leads to a bounded seismic hazard curve.</p>


2020 ◽  
Vol 1 (2) ◽  
Author(s):  
Cao Dinh Trong ◽  
Xuan-Nam BUI ◽  
Pham NAM HUNG ◽  
Thai ANH TUAN ◽  
Mai XUAN BACH ◽  
...  

This paper presents the seismic hazard assessment for Thuong Tan-Tan My quarries in Di An commune, Binh Duong province, Vietnam. Combination methods of gravity and magneto-telluric were used to estimate the dip angle and the width of the seismic source. The highest water column of 160 m will cause direct stress on the reservoir bottom with a maximum value of 1535.600 kPa and Coulomb stress of 68.693 kPa (at a depth of 2 km). The typical components of natural earthquake hazard (Mn.max = 5.0, depth of 10 km) in Thuong Tan - Tan My reservoir have the following values: peak ground acceleration PGA = 0.073 g ÷ 0.212 g; peak ground velocity PGV = 2.662 cm/s ÷ 7.984 cm/s; peak ground displacement PGD = 0.706 cm ÷ 1.918 cm at 10% probability of exceedance in 50 years. The typical components of triggered earthquake hazard (Mtr.max = 3.5, depth of 6 km) in Thuong Tan - Tan My reservoir have the following values: peak ground acceleration PGA = 0.024 g ÷ 0.172 g; peak ground velocity PGV = 0 ÷ 5.484 cm/s; peak ground displacement PGD = 0.061 cm ÷ 0.461 cm at 10% probability of exceedance in 50 years.


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