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1.
Economic importance of major ports is well known, and if ports are located in seismically active regions, then site-specific
seismic hazard studies are essential to mitigate the seismic risk of the ports. Seismic design of port sites and related structures
can be accomplished in three steps that include assessment of regional seismicity, geotechnical hazards, and soil structure
interaction analysis. In the present study, site-specific probabilistic seismic hazard analysis is performed to identify the
seismic hazard associated with four typical port sites of Gujarat state (bounded by 20°–25.5°N and 68°–75°E) of India viz.
Kandla, Mundra, Hazira, and Dahej ports. The primary aim of the study is to develop consistent seismic ground motion for the
structures within the four port sites for different three levels of ground shaking, i.e., operating level earthquake (72 years
return period), contingency level earthquake (CLE) (475 year return period), and maximum considered earthquake (2,475 year
return period). The geotechnical characterization for each port site is carried out using available geotechnical data. Shear
wave velocities of the soil profile are estimated from SPT blow counts using various empirical formulae. Seismicity of the
Gujarat region is modeled through delineating the 40 fault sources based on the seismotectonic setting. The Gujarat state
is divided into three regions, i.e., Kachchh, Saurashtra, and Mainland Gujarat, and regional recurrence relations are assigned
in the form of Gutenberg-Richter parameters in order to calculate seismic hazard associated with each port site. The horizontal
component of ground acceleration for three levels of ground shaking is estimated by using different ground motion attenuation
relations (GMAR) including one country-specific GMAR for Peninsular India. Uncertainty in seismic hazard computations is handled
by using logic tree approach to develop uniform hazard spectra for 5% damping which are consistent with the specified three
levels of ground shaking. Using recorded acceleration time history of Bhuj 2001 earthquake as the input time motion, synthetic
time histories are generated to match the developed designed response spectra to study site-specific responses of port sites
during different levels of ground shaking. It is observed that the Mundra and Kandla port sites are most vulnerable sites
for seismic hazard as estimated CLE ground motion is in order of 0.79 and 0.48 g for Mundra and Kandla port sites, respectively.
Hazira and Dahej port sites have comparatively less hazard with estimated CLE ground motion of 0.17 and 0.11 g, respectively.
The ground amplification factor is observed at all sites which ranges from 1.3 to 2.0 for the frequency range of 1.0–2.7 Hz.
The obtained spectral accelerations for the three levels of ground motions and obtained transfer functions for each port sites
are compared with provisions made in Indian seismic code IS:1893-Part 1 (2002). The outcome of present study is recommended for further performance-based design to evaluate the seismic response of the
port structures with respect to various performance levels. 相似文献
2.
The seismic hazard in the Sannio-Matese area has been worked out by a modification of the McGuire (1976) computing programme, taking into account the influence of nine potential seismic source zones.The method uses truncated-quadratic intensity-frequency distribution and azimuth-dependent intensity attenuation derived from isoseismal maps for each of the seismogenetic sources. A new modification has been introduced to take into account different decay of the intensity in the near (to VIII degree) and far (from VIII degree) field.Different assumptions about maximum possible intensities and truncation of intensity-frequency laws are used to evaluate the effects of the uncertainties on the computed hazard at high intensities. Intensities associated with different level of annual probability are computed for five test sites in the considered area. Maps displaying the expected intensity for a mean return period of 500 years (pa 0.002) are presented and compared with observed intensities.Presented at the XXIst General Assembly of the European Seismological Commission, Symposium on Methods of Seismic Hazard Assessment in Europe, Sofia, 23–27 August 1988. 相似文献
3.
A probabilistic procedure was applied to assess seismic hazard for the sites of five Greek cities (Athens, Heraklion, Patras, Thessaloniki and Volos) using peak ground acceleration as the hazard parameter. The methodology allows the use of either historical or instrumental data, or a combination of both. It has been developed specifically for the estimation of seismic hazard at a given site and does not require any specification of seismic sources or/and seismic zones. A new relation for the attenuation of peak ground acceleration was employed for the shallow seismicity in Greece. The computations involved the area- and site-specific parts. When assessing magnitude recurrence for the areas surrounding the five cities, the maximum magnitude, mmax, was estimated using a recently derived equation. The site-specific results were expressed as probabilities that a given peak ground acceleration value will be exceeded at least once during a time interval of 1, 50 and 100 years at the sites of the cities. They were based on the maximum peak ground acceleration values computed by assuming the occurrence of the strongest possible earthquake (of magnitude mmax) at a very short distance from the site and using the mean value obtained with the help of the attenuation law. This gave 0.24 g for Athens, 0.53 g for Heraklion (shallow) and 0.39 g Heraklion (intermediate-depth seismicity), 0.30 g for Patras, 0.35 g for Thessaloniki and 0.30 g for Volos. In addition, the probabilities of exceedance of the estimated maximum peak ground acceleration values were calculated for the sites. The standard deviation of the new Greek attenuation law demonstrates the uncertainty and large variation of predicted peak ground acceleration values. 相似文献
4.
A Probabilistic method is used to evaluate the seismic hazard of nineteen embankment dam sites in Jordan. A line source model developed by McGuire (1978) is used in this study. An updated earthquake catalogue covering the period from 1 A.D. to 1991 A.D. is used for this purpose. This catalogue includes all earthquakes that occurred in Jordan and adjacent areas, more specifically between latitudes 27.0°–35.5° N and longitudes 32.0°–39.0° E.Nine distinct seismic sources of potential seismic activities are identified. The seismic hazard parameters are determined using the method suggested by Kijko and Sellevoll (1989).The Peak Ground Acceleration (PGA) is selected as a measure of ground motion severity. Esteva (1974) attenuation relationship is used in evaluating PGA values at each dam site. Analysis is carried out for 50%, 90%, and 95% probability that is not being exceeded in a life time of 50, 100, and 200 years.Results of analysis indicate that PGA values are higher for dam sites closer to the Dead Sea Fault. This fault is believed to be responsible for most earthquake activities in Jordan and vicinity. The highest PGA value is found to be for Al-Karama dam site. 相似文献
5.
Preparing a seismic hazard model for Switzerland: the view from PEGASOS Expert Group 3 (EG1c) 总被引：1，自引：0，他引：1
The seismic hazard model used in the PEGASOS project for assessing earth-quake hazard at four NPP sites was a composite of four sub-models, each produced by a team of three experts. In this paper, one of these models is described in detail by the authors. A criticism sometimes levelled at probabilistic seismic hazard studies is that the process by which seismic source zones are arrived at is obscure, subjective and inconsistent. Here, we attempt to recount the stages by which the model evolved, and the decisions made along the way. In particular, a macro-to-micro approach was used, in which three main stages can be described. The first was the characterisation of the overall kinematic model, the “big picture” of regional seismogenesis. Secondly, this was refined to a more detailed seismotectonic model. Lastly, this was used as the basis of individual sources, for which parameters can be assessed. Some basic questions had also to be answered about aspects of the approach to modelling to be used: for instance, is spatial smoothing an appropriate tool to apply? Should individual fault sources be modelled in an intraplate environment? Also, the extent to which alternative modelling decisions should be expressed in a logic tree structure has to be considered. 相似文献
6.
Jagdish Chandra Joshi Tankeshwar Kumar Sunita Srivastava Divya Sachdeva Ashwagosha Ganju 《Natural Hazards》2018,91(3):1127-1164
Seismic hazard assessment is the key tool for rational planning, safety and design of infrastructures in seismically vulnerable regions. Gujarat is the only state in peninsular India with the maximum seismic hazard of large shallow earthquakes originating from intra-plate seismicity. Probabilistic seismic hazard assessment (PSHA) of Gujarat is carried out in this paper. Three seismogenic sources, namely Kutch, Saurashtra and Mainland Gujarat, are considered, and seismicity parameters are estimated separately for each region taking into account the completeness of the available earthquake data. Peak ground acceleration (PGA) of the horizontal component and spectral acceleration at specific periods are considered as the intensity measures. Ground motion predictive equation chosen was reported to be based on simulated ground motions and verified against the strong motion records in the study region. Results are reported for the 17 major cities at the bedrock and also for the soil sites. Apart from hazard curves, 2475 and 475 years of return periods are considered for the PGA and uniform hazard spectra (UHS). The results are compared with the present recommendations of Indian Standards. Key observations include (1) Indian Standards underpredict PGA in the entire Gujarat when the soil sites are considered and in a few cities even at the bedrock; (2) amplification of PGA (or short period hazard) on account of soil sites should be included in the Indian Standard, which is currently absent; (3) shape of the UHS indicates that a separate amplification is required at the hyperbolic portion; and (4) ratio of 2475–475 years of PGA, which is considered 2.0 in Indian Standard, should be reduced to 1.5. Time-dependent recurrence model is also included in this paper and compared with conventional PSHA. General observations include that (1) hazard may increase significantly on account of time dependency; (2) this also influences the disaggregation and in turn the selection of ground motions; and (3) time since last earthquake significantly influences the extent of the effect of time dependency. 相似文献
7.
Shafiq Ur Rehman Muhammad Khalid Asif Ali Abd El-aziz Khairy Abd El-Aal 《Arabian Journal of Geosciences》2013,6(9):3481-3492
Gwadar City is located at the coastline of Pakistan. The city is currently in a phase of development, which is expected to become a future economic hub for Pakistan. This has led us to choose Gwadar for seismic hazard evaluation. Seismic hazard analysis for Gwadar is carried out using deterministic and probabilistic seismic hazard analysis techniques. The present study will help in sustainable development of a future large city and economic hub for Pakistan on ways of coping from a major threat of earthquake hazard. In deterministic seismic hazard analysis, line sources were identified close to Gwadar. Based on the analysis of maximum magnitude and closest distance (worse conditions), Makran subduction zone was identified out of all the line sources with earthquake potential of 8.2 at a distance of 30 km. This yielded a peak ground acceleration value of 0.38 g for Gwadar City. In second phase, probabilistic seismic hazard analysis technique with the area source modeling was adopted to acquire results at different return periods. For this purpose, seismic data were collected from the Pakistan Meteorological Department and International Seismological Center (2010) databases for development of a comprehensive data catalog. The a and b values were obtained using regression analysis for each source zone, and probabilistic analysis yielded the results of 0.34 g for a return period of 500 years. As per building codes of Pakistan, areas or cities with ground acceleration greater than 0.32 g are considered in seismic zone 4, and both deterministic and probabilistic hazard analysis place the city in seismic zone 4. These values correspond to rock site with shear wave velocity of 760 m/s. 相似文献
8.
Testing a new hybrid approach to seismic hazard assessment: an application to the Calabrian Arc (Southern Italy) 总被引：1，自引：1，他引：0
We tested a new hybrid method for the evaluation of seismic hazard. A recently proposed fault segmentation and earthquake recurrence model of peninsular Italy suggests that the interval for which the local historical catalogue is complete is shorter than the mean recurrence time of individual large faults (1000 years), or at the most comparable. These new findings violate the fundamental assumption of historical probabilistic seismic hazard methods that the historical record is representative of the activity of all the seismogenic sources. The hybrid method we propose uses time-dependent modelling of the major earthquakes and catalogue-based historical probabilistic estimates for all minor events. We assume that the largest earthquakes are characteristic for individual discrete fault segments, model their probability of occurrence by a renewal process and compute the shaking associated with each of them with a simplified procedure. Then we calculate the probability of exceeding a given threshold of peak ground acceleration for specific sites as the aggregate probability of occurrence of large characteristic earthquakes and minor shocks. We apply the method to the Calabrian Arc (Southern Italy) performing the calculations for five major towns. The exposure to seismic hazard of Reggio Calabria, Catanzaro and Vibo Valentia, which locate close to recently activated large faults, decreases with respect to traditional time-independent estimates. On the contrary, an increase of seismic hazard is obtained for Castrovillari, which locates in an area where large faults displaying Holocene activity have been recently recognized but no significant earthquake is reported in the historical catalogue. Cosenza has the highest probability to experience a significant peak ground acceleration with both the new hybrid and the traditional approaches. We wish to stress that the present results should be interpreted only in terms of the differences between the new hybrid and the traditional approaches, not for their absolute values, and that they are not intended to be used for updating or modifying the current national seismic zonation. 相似文献
9.
A probabilistic seismic hazard assessment at Kancheepuram in Southern India was carried out with the scope of defining the seismic input for the vulnerability assessment of historical and monumental structures at the site, in terms of horizontal Uniform Hazard Spectra and a suite of spectrum-compatible natural accelerograms to perform time-history analysis. The standard Cornell?CMcGuire and a zone-free approach have been used for hazard computations after the compilation of a composite earthquake catalogue for Kancheepuram. Epistemic uncertainty in the seismic hazard was addressed within a logic-tree framework. Deaggregation of the seismic hazard for the peak ground acceleration shows low seismicity at Kancheepuram controlled by weak-to-moderate earthquakes with sources located at short distances from the archaeological site. Suites of natural accelerograms recorded on rock have been selected by imposing a custom-defined compatibility criterion with the probabilistic spectra. The site of Kancheepuram is characterized by a seismicity controlled by weak-to-moderate earthquakes with sources at short distances from the site, the PGA expected for 475- and 2,475-year return period are, respectively, 0.075 and 0.132?g. The Indian code-defined spectra (DBE and MCE) tend to underestimate spectral ordinates at low periods. On the other hand, the PGA are comparable and the spectral ordinates for longer periods from the probabilistic study are significantly lower. 相似文献
10.
Generally the seismic hazard of an area of interest is considered independent of time. However, its seismic risk or vulnerability, respectively, increases with the population and developing state of economy of the area. Therefore, many areas of moderate seismic hazard gain increasing importance with respect to seismic hazard and risk analysis. However, these areas mostly have a weak earthquake database, i.e., they are characterised by relative low seismicity and uncertain information concerning historical earthquakes. In a case study for Eastern Thuringia (Germany), acting as example for similar places in the world, seismic hazard is estimated using the probabilistic approach. Because of the lack of earthquakes occurring in the recent past, mainly historical earthquakes have to be used. But for these the actual earthquake sources or active faults, needed for the analysis, are imprecisely known. Therefore, the earthquake locations are represented by areal sources, a common practice. The definition of these sources is performed carefully, because their geometrical shape and size (apart from the earthquake occurrence model) influence the results significantly. Using analysis tools such as density maps of earthquake epicentres, seismic strain and energy release support this. Oversizing of areal sources leads to underestimation of seismic hazard and should therefore be avoided. Large location errors of historical earthquakes on the other hand are represented by several alternative areal sources with final superimposition of the different results. In a very similar way information known from macroseismic observations interpreted as source rather than as site effects are taken into account in order to achieve a seismic hazard assessment as realistic as possible. In very local cases the meaning of source effects exceeds those of site effects very likely. The influence of attenuation parameter variations on the result of estimated local seismic hazard is relatively low. Generally, the results obtained by the seismic hazard assessment coincide well with macroseismic observations from the thoroughly investigated largest earthquake in the region. 相似文献
11.
12.
The republic of El Salvador in Central America is an area of high seismic hazard where at least twelve destructive earthquakes have occurred this century alone. The principal sources of seismic hazard are earthquakes associated with the subduction of the Cocos plate in the Middle America Trench and upper-crustal earthquakes in the chain of Quaternary volcanoes that runs across the country parallel to the subduction trench. Hazard assessments for Central America have suggested almost uniform distribution of hazard throughout El Salvador. Seismic zonations for three successive building codes in El Salvador simply divide the country into two regions, with the higher hazard zone containing the volcanoes and the coastal areas. Historical records suggest that the greatest hazard is posed by the upper-crustal earthquakes concentrated on the volcanic centres which, although of smaller magnitude than the subduction events, are generally of shallow focus and coincide with the main population centres. These earthquakes have repeatedly caused intense damage over small areas in the vicinity of some of the main volcanoes. This study focuses on El Salvador to explore the capability of different approaches to hazard assessment to reflect significant variations of seismic hazard within small geographical areas. In the study, three 'zone-free' methods are employed as well as the Cornell–McGuire approach. The results of the assessments are compared and their implications for seismic zoning for construction and insurance purposes are discussed. 相似文献
13.
In this work, an attempt has been made to evaluate the spatial variation of peak horizontal acceleration (PHA) and spectral
acceleration (SA) values at rock level for south India based on the probabilistic seismic hazard analysis (PSHA). These values
were estimated by considering the uncertainties involved in magnitude, hypocentral distance and attenuation of seismic waves.
Different models were used for the hazard evaluation, and they were combined together using a logic tree approach. For evaluating
the seismic hazard, the study area was divided into small grids of size 0.1° × 0.1°, and the hazard parameters were calculated
at the centre of each of these grid cells by considering all the seismic sources within a radius of 300 km. Rock level PHA
values and SA at 1 s corresponding to 10% probability of exceedance in 50 years were evaluated for all the grid points. Maps
showing the spatial variation of rock level PHA values and SA at 1 s for the entire south India are presented in this paper.
To compare the seismic hazard for some of the important cities, the seismic hazard curves and the uniform hazard response
spectrum (UHRS) at rock level with 10% probability of exceedance in 50 years are also presented in this work. 相似文献
14.
Within the framework of the performance based earthquake engineering, site specific earthquake spectra for Van province has been obtained. It is noteworthy that, in probabilistic seismic hazard assessment, as a first stage data from geological studies and records from the instrumental period were compiled to make a seismic source characterization for the study region. The probabilistic seismic hazard curves were developed based on selected appropriate attenuation relationships, at rock sites, with a probability of exceedance 2, 10 and 50% in 50 yrs period. The obtained results are compared with the spectral responses proposed for seismic evaluation and retrofit of building structure in Turkish Earthquake Code (2007), section 7. The acceleration response spectrums obtained from probabilistic seismic hazard analysis are matched to adjust earthquake accelerograms recorded during the 2011 Van earthquakes by using SeismoMatch v2.0 software. The aim of this procedure is to obtain a set of reasonable earthquake input motions for the seismic evaluation of existing buildings. 相似文献
15.
Vladimír Schenk Zdeňka Schenková František Mantlík Pavel Kottnauer 《Natural Hazards》1989,2(3-4):267-287
Within the activity of the ESC Subcommission 8 Engineering Seismology, Project TERESA, seismic hazard calculations have been performed for two areas of a different earthquake activity. Fundamental seismological data (earthquake catalogues, macroseismic observations and maps) and some additional geological information were analyzed and processed to prepare inputs for hazard computations. Great attention has been paid to verifying the reliability of the input data. Seismic hazards obtained for five sites of the region of high seismic activity (Sannio-Matese, southern Italy) and six sites of the region of low seismic activity (Brabant Massif and northern Rhine, Belgium—The Netherlands—Germany) are presented and discussed. 相似文献
16.
《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2013,7(3-4):173-185
The most important seismic hazard parameters required to demarcate seismic zones are the peak horizontal acceleration (PHA) and spectral acceleration (SA). The two approaches for evaluation of seismic hazard are the probabilistic seismic hazard analysis and the deterministic seismic hazard analysis (DSHA). The present study evaluates the seismic hazard of the South Indian Peninsular region based on the DSHA methodology. In order to consider the epistemic uncertainties in a better manner, a logic tree approach was adopted in the evaluation of seismic hazard. Two types of seismic sources and three different attenuation relations were used in the analysis. The spatial variation of PHA (mean and 84th percentile values) and SA values for 1 Hz and 10 Hz at bedrock level (84th percentile values) for the entire study area were evaluated and the results are presented here. The surface level peak ground acceleration (PGA) values will be different from that of the bedrock level values due to the local site conditions. The PGA values at ground surface level were evaluated for four different National Earthquake Hazard Reduction Program site classes by considering the non-linear site response of different soil types. The response spectra for important cities in South India were also prepared using the deterministic approach and the results are presented in this paper. 相似文献
17.
概率地震危险性评价系统开发 总被引：1，自引：0，他引：1
工程建设时必须对工程场地的地震危险性进行评价,并且对工程结构物要采取抗震设计。由于相关部门往往针对某一地区只提供一个地震设防加速度范围值或地震设防烈度值,而且某一地震烈度值所对应的加速度值的范围也很大,使得在实际应用中给具体工程安全、经济地选用合适的抗震设防加速度带来一定困难;为解决这个问题,本文以概率地震危险性评价理论为基础,开发了一套地震危险性评价系统。利用该评价系统根据相关地震活动性参数,可以方便、快速地计算出具体工程应该采用的抗震设防加速度值,从而解决了工程活动中安全、经济地选用抗震设防加速度值的问题。文中还针对潜在线源和潜在面源的处理难以在程序上实现这一难题,分别提出了一种精确求解和近似求解的算法。本文并以实例进行了评价计算,计算结果与中国地震局公布的数据符合较好,从而验证了开发的评价系统具有较好的可信度。 相似文献
18.
B. C. Papazachos Ch. A. Papaioannou B. N. Margaris N. P. Theodulidis 《Natural Hazards》1993,8(1):1-18
A semi-probabilistic approach to the seismic hazard assessment of Greece is presented. For this reason, a recent seismotectonic model for shallow and intermediate depth earthquake sources, based on historical as well as on instrumental data, was used. Different attenuation formulae were proposed for the macroseismic intensity and the strong ground motion parameters for the shallow and the intermediate focal depth shocks. The data were elaborated in terms of McGuire's computer program, which is based on the Cornell's method.A grid of equally spaced points at 20 km distance was made and the seismic hazard recurrence curves for various parameters of the seismic intensity was estimated for each point. Finally, seismic hazard maps for the area of Greece were compiled utilizing the entire range of recurrence curves. These maps depict areas of equal seismic hazard and for every area the analytical relations of the typeSI =f(Tm), whereSI is a seismic intensity parameter andTm is the mean return period, were determined. 相似文献
19.
Mumbai city, the economical capital of India, is located on the west coast of stable intra-plate continental region of Peninsular India which has an experience of significant historical earthquakes in the past. The city stood as the fourth most populous city in the world. Recent seismo-tectonic studies of this city highlighted the presence of active West coast fault and Chiplun fault beneath the Deccan basalt. In the present study, spatial variability of probabilistic seismic hazard for Mumbai region (latitudes of 18.85–19.35°N and longitudes of 72.80–73.15°E at a grid spacing of 0.05°) which includes Mumbai city, Suburban, part of Thane district and Navi Mumbai, in terms of ground motion parameters; peak horizontal acceleration and spectral acceleration at 1.0-s period for 2 and 10 % probability of exceedance in 50 years are generated. The epistemic uncertainty in hazard estimation is accounted by employing seven different ground motion prediction equations developed for worldwide shallow crustal intra-plate environments. Further, the seismic hazard results are deaggregated for Mumbai (latitude 18.94°N, longitude 72.84°E) to understand the relative contributions of earthquake sources in terms of magnitude and distance. The generated hazard maps are compared with the zoning specified by Indian seismic code (IS1893: Part 1 in Indian standard criteria for earthquake-resistant design of structures, Part 1—General provisions and buildings. Bureau of Indian Standards, New Delhi, India, 2002) for rocky site. Present results show an underestimation of potential seismic hazard in the entire study region by non-probabilistic zoning prescribed by IS1893: Part 1 with significantly higher seismic hazard values in the southern part of Navi Mumbai. 相似文献
20.
First Order Seismic Microzonation of Delhi,India Using Geographic Information System (GIS) 总被引：2，自引：4，他引：2
William K. Mohanty M. Yanger Walling Sankar Kumar Nath Indrajit Pal 《Natural Hazards》2007,40(2):245-260
A first order seismic microzonation map of Delhi is prepared using five thematic layers viz., Peak Ground Acceleration (PGA)
contour, different soil types at 6 m depth, geology, groundwater fluctuation and bedrock depth, integrated on GIS platform.
The integration is performed following a pair-wise comparison of Analytical Hierarchy Process (AHP), wherein each thematic
map is assigned weight in the 5-1 scale: depending on its contribution towards the seismic hazard. Following the AHP, the
weightage assigned to each theme are: PGA (0.333), soil (0.266), geology (0.20), groundwater (0.133) and bedrock depth (0.066).
The thematic vector layers are overlaid and integrated using GIS. On the microzonation theme, the Delhi region has been classified
into four broad zones of vulnerability to the seismic hazard. They are very high (> 52%), high (38–52%), moderate (23–38%)
and less ( < 23%) zones of seismic hazard. The “very high” seismic hazard zone is observed where the maximum PGA varies from
140 to 210 gal for a finite source model of Mw 8.5 in the central seismic gap. A site amplification study from local and regional earthquakes for Delhi region using Delhi
Telemetry Network data shows a steeper site response gradient in the eastern side of the Yamuna fluvial deposits at 1.5 Hz.
The ‘high’ seismic hazard zone occupies most of the study area where the PGA value ranges from 90 to 140 gal. The ‘moderate’
seismic hazard zone occurs on either side of the Delhi ridge with PGA value varying from 60 to 90 gal. The ‘less’ seismic
hazard zone occurs in small patches distributed along the study area with the PGA value less than 60 gal. Site response studies,
PGA distribution and destruction pattern of the Chamoli earthquake greatly corroborate the seismic hazard zones estimated
through microzonation on GIS platform and also establishes the methodology incorporated in this study. 相似文献