The microzonation study in the region has been formulated into two different aspects–geomorphological and seismolog- ical. The former is derived from thematic layers compris- ing of surface geology, soil cover, slope, rock outcrop, and landslide hazard, which are integrated to achieve geologi- cal hazard distribution. The corresponding thematic layers have been developed by Nath (2004). The major datasets in- clude IRS–1C LISS III digital data, toposheets from Survey of India, surface geological maps, soil taxonomy map based on composition, grain size and lithology from the National Bureau of Soil Survey and seismic refraction profiles. The percent slope mapping has been done with Triangulated Ir- regular Network (TIN) on GIS. Rock outcrop and landslide scarp region had been identified and vectorized into two sep- arate polygon coverage. The latter highlights the relevant hazard conduced from seismic activities instead of geotech- nical landslide hazard zonation. The seismological themes, namely surface consistent peak ground acceleration and pre- dominant frequency were, thereafter, integrated with the ge- ological hazard distribution to obtain the seismichazard mi- crozonation map of the Sikkim Himalaya.
Abstract. Seismicmicrozonation is a process of estimat- ing site-specific effects due to an earthquake on urban cen- ters for its disaster mitigation and management. The state of West Bengal, located in the western foreland of the Assam– Arakan Orogenic Belt, the Himalayan foothills and Surma Valley, has been struck by several devastating earthquakes in the past, indicating the need for a seismotectonic re- view of the province, especially in light of probable seis- mic threat to its capital city of Kolkata, which is a major industrial and commercial hub in the eastern and northeast- ern region of India. A synoptic probabilistic seismic haz- ard model of Kolkata is initially generated at engineering bedrock (V s 30 ∼ 760 m s −1 ) considering 33 polygonal seis- mogenic sources at two hypocentral depth ranges, 0–25 and 25–70 km; 158 tectonic sources; appropriate seismicity mod- eling; 14 ground motion prediction equations for three seis- motectonic provinces, viz. the east-central Himalaya, the Bengal Basin and Northeast India selected through suitability testing; and appropriate weighting in a logic tree framework. Site classification of Kolkata performed following in-depth geophysical and geotechnical investigations places the city in D1, D2, D3 and E classes. Probabilistic seismichazard as- sessment at a surface-consistent level – i.e., the local seismichazard related to site amplification performed by propagat- ing the bedrock ground motion with 10 % probability of ex- ceedance in 50 years through a 1-D sediment column using an equivalent linear analysis – predicts a peak ground accel- eration (PGA) range from 0.176 to 0.253 g in the city. A de- terministic liquefaction scenario in terms of spatial distribu- tion of liquefaction potential index corresponding to surface PGA distribution places 50 % of the city in the possible liq- uefiable zone. A multicriteria seismichazardmicrozonation framework is proposed for judicious integration of multiple
in patches around Adyar River and few patches distributed below Cooum River in the south western part of the city. The areas in the southern part of Chennai represent lacustrine de- posits is underlined by marine black clay as evident in Tara- mani areas. The maximum depth to basement is 14 m. The central part of the city has mainly fluvial origin of flood plain deposits as evidence from the flowing Adyar and Cooum rivers. The upstream portion of Adyar and Cooum rivers have a moderate slope and in the down stream, the rivers are very gentle to flat in coastal areas. These areas in the northern part of the city represent black clay and alluvium of marine origin with maximum depth to basement of 30 m and patches of these areas show high hazard. The western and northwest- ern part of Chennai falls under moderate hazard. These areas represent the shale and clay of the Gondwana age and are also correlated with lake fill deposits. The remaining areas are prone to low seismichazard. It can be concluded that the half of the Chennai city is prone to moderate to high haz- ard. The resultant map provides regional pictures on seismichazard of Chennai city and is useful information in construc- tion planning of forthcoming buildings in the city. Also it is helpful as a base material to identify seismic risk of Chennai city.
Abstract. The town of Idrija is located in an area with an increased seismichazard in W Slovenia and is partly built on alluvial sediments or artificial mining and smelting de- posits which can amplify seismic ground motion. There is a need to prepare a comprehensive seismicmicrozonation in the near future to support seismichazard and risk assessment. To study the applicability of the microtremor horizontal-to- vertical spectral ratio (HVSR) method for this purpose, 70 free-field microtremor measurements were performed in a town area of 0.8 km 2 with 50–200 m spacing between the points. The HVSR analysis has shown that it is possible to derive the sediments’ resonance frequency at 48 points. With the remaining one third of the measurements, nearly flat HVSR curves were obtained, indicating a small or neg- ligible impedance contrast with the seismological bedrock. The isofrequency (a range of 2.5–19.5 Hz) and the HVSR peak amplitude (a range of 3–6, with a few larger values) maps were prepared using the natural neighbor interpolation algorithm and compared with the geological map and the map of artificial deposits. Surprisingly no clear correlation was found between the distribution of resonance frequencies or peak amplitudes and the known extent of the supposed “soft” sediments or deposits. This can be explained by rela- tively well-compacted and rather stiff deposits and the com- plex geometry of sedimentary bodies. However, at several individual locations it was possible to correlate the shape and amplitude of the HVSR curve with the known geolog- ical structure and prominent site effects were established in different places. In given conditions (very limited free space and a high level of noise) it would be difficult to perform an active seismic refraction or MASW measurements to inves- tigate the S-wave velocity profiles and the thickness of sed-
Local site conditions (ex. near surface geological condi- tions or topography) can, additionally to distance effects, am- plify/reduce the peak ground acceleration (PGA) site value. Building codes in earthquake prone areas account for local site conditions, using a categorisation into site classes of sub- surfaces and parameters like sediment infills in irregular ge- ological structures. Long distance earthquakes can have dis- astrous effects on high-density urban settlements, if alluvial soil deposits amplify the ground motion. The microzona- tion increasingly contributes to seismic risk evaluation in ur- ban areas. Urban microzonation is researched by the groups of Parvez et al. (2004), Moldoveanu et al. (2004), Panza et al. (2001), Ansal (2002), and Faccioli and Pessina (2003). Parvez et al. (2004) initiated a project towards an integrated expert system, to use seismicmicrozonation parameters to- gether with information on the earth, environmental, socio- economic and political systems, in urban planning processes, when elaborating land-use maps, able to provide well esti- mated seismic inputs for earthquake resilient building design. Parvez et al. (2004) recognised the multidisciplinarity of this work, requiring input from seismology, history, archaeology, geology and geophysics. Parvez et al. (2004) proposed a first level microzonation map using microtremor measurements and a second order one using measured or numerically sim- ulated seismichazard parameters (PGA, PeakGroundVeloc- ity) relevant for seismic building design in urban areas.
The seismicity rates for models 1, 2, and 3 are shown in Figure 8. Models 1 and 2 reveal a similar pattern with minor variations, due to the small number of earthquakes included from the local catalogs in model 2. However, model 3, which includes historical earthquakes from 1900, shows a different pattern. We have less confidence in model 3 because of the historical catalog ’ s incompleteness. The number of earth- quakes in the longer time span of the historical catalog is small (207 earthquakes in 64 years); many low-magnitude events must have been missed — either there is no informa- tion or they were not felt by people (e.g., earthquakes that occurred in the sea). The historical catalog has a higher com- pleteness magnitude and contains few Red Sea earthquakes. As a result, the median values over a longer time span of the catalog remain low along the Red Sea rift resulting in a dif- ferent pattern for model 3. The temporal variations in the spa- tial completeness magnitude pose a challenge for seismicity rate estimations, which is beyond the scope of our present work. However, as shown in Figure 8, we believe that ex- cluding the historical earthquakes may underestimate the hazard levels in some sites and care should be taken when interpreting the seismicity rates of model 1 or 2.
Rapid urbanisation shapes disaster risks through a complex association of concentrated population, social exclusion and poverty compounded by physical vulnerability. This can be seen in the consequences of unsuited land use, inadequate protection of urban infrastructures, ineffective building code enforcement, poor construction practice and limited opportunities to transfer or spread risk. The underlying problems of growing vulnerability to natural and technological hazards are largely an outcome of short-sighted development activities considering these factors, structural mitigation measures are the key to make a significant impact towards earthquakes safety in the word. The principal purpose of hazard mitigation is the protection of life, even when the risk to a single individual at any time is comparatively small. Concerned with the impact of natural disasters in the background of united Nation’s resolution and following the Yokohama Strategy for a Safer World, May,1994, there is paradigm shift from post disaster reconstruction and relief to post disaster pro-active approach to reduce the impact of natural hazards.
The seismic group is sponsoring and has recommended that its member countries participate in a blind benchmark competition of a model three-story reinforced concrete (RC) structure organized by Commissariat a’ l Energie Atomique (CEA) and Electricite de France (EDF). Because three- dimensional (torsion) effects and nonlinear response are a concern in the field of earthquake engineering research and building regulation, CEA and EDF have organized and supported this benchmark competition. A three-story RC structure at ¼ scale was built and placed on the AZALEE shake table at the CEA laboratory in Saclay, France. The aim of the proposed benchmark is to compare and validate various approaches used by the international participants to model the dynamic response analysis techniques for RC structures subjected to simulated earthquakes and exhibiting both three-dimensional (torsion) and nonlinear behaviour. This analysis includes evaluation of loads induced by internal equipment, quantification of margins in design methodologies, and conducting realistic methods to quantify variability to produce fragility data. The blind benchmark competition has the following two objectives:
In addition to the seismic issues, the technical support program included a wider spectrum of safety-related activities at ANPP through ANRA. Specifically, safety concerns regarding the performance of critical reactor systems, such as the primary side feed and bleed (F&B) operation in the event of total loss of off-site power due to a seismic event, were being addressed. ANPP was designed so that the residual and accumulated heat removal after shutdown was primarily performed by maintaining feed-water supply to the secondary sides of the steam generators (SG) and dumping steam to the atmosphere or to the turbine condensers, or water to the technological condenser in the water-water mode. The primary side feed and bleed (F&B) possibility was not considered in the original design. Furthermore, to make matters more challenging, the primary F&B procedure application was prevented by a lack of safety valves in the pressurizer qualified for steam-water mixture, which was necessary to relieve the coolant to the relief tank and then to the confinement. As a result, and during the ANPP Unit 2 upgrade, the original pressurizer safety valves (PRZ SV,) were replaced by the new higher capacity valves qualified for steam-water mixture. The installation of new valves allowed application of primary side F&B operation as a backup measure to remove the residual and accumulated heat from the core. In a later section an analysis performed on the new system is described. The primary goal was to demonstrate the core cooling capability of the plant using the high-pressure injection (HPI) system (feed) and pressurizer safety valves (bleed) and to evaluate temperature changes in the Borated Water Supply Tank (BWST). The Regulatory Authority of Armenia will utilize results of the analyses for endorsement of F&B procedures. Furthermore, technical support activities associated with open issues of the new dry fuel storage facility, including seismic safety, and the Safety Analysis Report (SAR), including cask drop safety assessment, were initiated.
Considering the various types of sources surrounding a site considered, their location and focal depth as well as attenuation patterns characterizing the region analyzed, cumulative distribution function of peak ground accel- eration can be computed by using Equation (8). Then for a given probability of exceedance , in other words for a specific hazard level, the PGA values can be computed. By using the aid of computer program (HAZ81), we di- vided the study area into a grid with 0.25 × 0.25 degree area.
The equation (3) is called the ambiguity relation of probabilistic seismichazard analysis, because it shows that the result of such an analysis is not unique. Different teams acting in different projects with a different organisation will get different results even if their understanding of the key topics of the analysis is very similar or even equal. The problem can only be reduced by minimizing the amount of random parameters, used in the analysis or by providing exact models for the correlation between different sources of uncertainties. The hunt for uncertainties launched by the SSHAC-procedures by separating epistemic and aleatory uncertainties involving their independent treatment leads just to the contrary. The problem gets even worse by the use of experts in the case, when project interfaces between different project tasks exist and the aggregation of expert opinion is integrated directly into the logic tree. This was the case in the PEGASOS project which used different experts (expert teams) for source characterisation (SP1), ground motion characteristics (SP2) and site effects (SP3). The separation of the project led to 3 additional branches of the logic tree thus skewing up the results of the study without relation to seismic topics.
rock peak ground acceleration (PGA) hazard curves for one of the locations. This figure also shows the corresponding soil PGA hazard curve, transformed from the rock curves using the soil/rock amplification relation presented in . These soil PGA hazard curves correspond to Eq. 5. Each of the circle symbols on the hazard curve in Figure 4 indicates where a magnitude-distance deaggregation matrix value [Eq. 6] is available to use in ASHLES. Figure 5 is an example ground motion deaggregation matrix for one point along the hazard curve. As an observation for this particular site at this example ground motion and hazard level, the highest peaks are coming from the dominating contribution to ground motion hazard of the Hayward-Rodgers Creek (63%) and San Andreas (17%) faults, identifiable from their distinguishing magnitude and distance distributions. This deaggregation matrix indicates that much of the remaining PGA hazard contribution is coming from nearby (0 to 10km) smaller magnitude events not associated with any given fault. Deaggregation matrices for different points along a hazard curve will indicate differing relative contributions by the various seismic sources. As discussed above, and indicated by the summation over a i in Eq. 17, the evaluation of annual probability of liquefaction
17. "Catalog of the Seismicity of Sudan fo؛' the Period 1632 - 1994", Published by the Seisniological Research Unit, National Center for Research; Sudan, 1996. 18. Joseph, M. Bracci, Andrei, M. Reinhorn, and John, B. Mander, "Seismic Resistance of Reinforced Concrete Frame Structures Designed for Gravity Loads; Performance of Structural Building", AC1 Structural Journal, Vol. 92, No. 5, Sep. - Oct. 1995, pp. 597 - 609.
In the presented manuscript one engineering project location was selected as the case study. For this location high rise building construction was planned (more than 12 floors). For this location complex survey was applied such as geological and geotechnical investigations, geophysical survey (seismic profiling and downhole test in wells), seismichazard assessment, site-dependent seismic ha- zard assessment. All needed data for probabilistic seismichazard assessment such as active faults, seismic source zones, seismic catalogues and seismic para- meters, ground motion attenuation models, etc. were collected and reviewed. At the end all investigations were merged and final conclusions were done.
Figure 1. Overall concept of the GeoHazData hazard map inventory tool. The metadata editor generates ISO 19115-compatible metadata registered in an Open Geospatial Consortium (OGC, http://www.opengeospatial.org/) catalogue . This catalogue is stored on a publicly accessible server. The acquired data can be shared using a dedicated server, published on any other OGC compliant catalogue or exported locally in XML format. A Web Map Service (WMS) enables viewing the extent and content of the metadata. Finally, this catalogue can be interrogated by any other OGC client application.
Figure 1 shows the conceptual relationship between the tools being developed and tested in this study. Hazard Characterization and the effects of Soil Structure Interaction are not explicitly considered in the scope of the study. Rather, a characteristic sets of acceleration time histories are used as inputs to fixed base seismic analysis of selected structures. The time histories represent the review level ground motion response spectra (GMRS) for the selected site. Because of the computational expense of high fidelity finite element models of NPP facilities, a major challenge in the analysis is the development of reduced order (or surrogate) models that can be used in uncertainty analyses but still retain a high level of fidelity. The development of the reduced order models as well as the uncertainty analyses are accomplished using the RAVEN code (Alfonsi et al., 2013). Additionally, the tools also assess the CCF of components arising from correlation in structural response. CCF is an important input to the overall assessment of system failure probability by SAPHIRE (Smith et al., 2008) or an equivalent commercial risk assessment code.
To illustrate the individual model contributions, "tornado" plots are used, which represent the systematic sensitivity analysis of the subproject models and their parameters. The contributions for all three subprojects as well as each expert for one example site are shown in Figures 1 and 2. The upper part of the graphs show the range of ground motions for the experts (teams). The sensitivity of the hazard results for 100 Hz (here interpreted as PGA) as a function of the assigned weights on each branch of the logic trees for all dominant parameters can be found in the lower part of the graph. If a symbol is on the right side of the vertical axis, it means that this parameter or model contributes above-average to the overall hazard. As can be seen, individual branches of the logic tree, e.g. the seismic source, the spatial smoothing or the maximum magnitude lead to a range of the ground motions of a factor of 1.5 to 2.0.
Implementation of reinforced concrete jacketing for seismic strengthening of the columns will result in longitudinal seismic load path transfer through bending and shear of upgraded columns, which will have the required higher capacity. Four-sided jacketing of the columns with a ductile design, which will be implemented by adding concrete, longitudinal reinforcement and closely-spaced ties, has the best seismic behavior and monolithic action. Implementation of other materials as steel or carbon fibers for jacketing was also considered as an option.
So far, different practical and theoretical researches have been conducted on the seismic performance of structures equipped with base isolators. Tena-Colunga & Gómez- Soberón (2002)  compared the displacement response amplifications of the base isolation system of an asymmetric structure with the response of a symmetric structure. It was shown that base displacement demand amplifications are higher for larger eccentricities of superstructures, and they depend on the periods of isolated structures. Based on their conclusions, asymmetry reduces the effectiveness of base isolation systems, since more exposed isolators tend to deform plastically, while others still remain elastic. Moreover, contrary to expectations, maximum base displacement is recorded for unidirectional eccentricity instead of bidirectional eccentricity. Karim & Yamazki (2007) investigated the effects of using base isolators on the fragility curves in highway bridges and suggested a simple method of deriving the mentioned curves. They modelled 30 bridges, with different heights, weights and overstrength factors, subjected to 250 earthquake records. They used PGA and PGV as Intensity Measure (IM) in their research. Comparing the curves plotted for isolated and fixed base structures, they concluded that isolation increased fragility in tall pier bridges compared to short pier ones. They designed a type of isolator for all pier heights; however, they did not consider the effect of isolator damage. Han et al (2014)  has used the seismic risk analysis for an old non-ductile RC frame building before and after retrofit with base isolation. The study revealed that base isolation can greatly reduce the seismic risk for higher damage levels, as expected. More importantly, the results also indicated that neglecting aftershocks can cause considerable underestimation of the seismic risk. Dezfuli et al (2018)  developed a new constitutive material model for SMA-LRB. The outcome of their study shows that SMA wires can efficiently reduce the shear strain demand in LRBs. Nakhostin Faal and Poursha (2017)  successfully extended the modal pushover analysis and N 2 method to