Mankind is facing the problem due to earthquake hazard since prehistoric times. Many of the developed and developing countries are under constant threats from earthquakes hazards. Theories of plate tectonics and engineering seismology have helped to understand earthquakes and also to predicate earthquake hazards on a regional scale. However, the regional scale hazard mapping in terms of seismic zonation has been not fully implemented in many of the developing countries like India. Agglomerations of large population in the Indian cities and poor constructions have raised the risk due to various possible seismic hazards. First and foremost step towards hazard reduction is estimation of the seismic hazards in regional scale. Objective of this study is to estimate the seismic hazard parameters for Lucknow, a part of Indo-Gangetic Basin (IGB) and develop regional scale microzonation map. Lucknow is a highly populated city which is located close to the active seismic belt of Himalaya. This belt came into existence during the Cenozoic era (40-50 million years ago) and is a constant source of seismic threats. Many of the devastating earthquakes which have happened since prehistoric times such as 1255 Nepal, 1555 Srinagar, 1737 Kolkata, 1803 Nepal, 1833 Kathmandu, 1897 Shillong, 1905 Kangra, 1934 Bihar-Nepal, 1950 Assam and 2005 Kashmir. Historic evidences show that many of these earthquakes had caused fatalities even up to 0.1 million. At present, in the light of building up strains and non-occurrence of a great event in between 1905 Kangra earthquake and 1934 Bihar-Nepal earthquake regions the stretch has been highlighted as central seismic gap. This location may have high potential of great earthquakes in the near future. Geodetic studies in these locations indicate a possible slip of 9.5 m which may cause an event of magnitude 8.7 on Richter scale in the central seismic gap. Lucknow, the capital of Uttar Pradesh has a population of 2.8 million as per Census 2011. It lies in ZONE III as per IS1893: 2002 and can be called as moderate seismic region. However, the city falls within 350 km radial distance from Main Boundary Thrust (MBT) and active regional seismic source of the Lucknow-Faizabad fault. Considering the ongoing seismicity of Himalayan region and the Lucknow-Faizabad fault, this city is under high seismic threat. Hence a comprehensive study of understanding the earthquake hazards on a regional scale for the Lucknow is needed. In this work the seismic microzonation of Lucknow has been attempted. The whole thesis is divided into 11 chapters. A detailed discussion on the importance of this study, seismicity of Lucknow, and methodology adopted for detailed seismic hazard assessment and microzonation are presented in first three chapters. Development of region specific Ground Motion Prediction Equation (GMPE) and seismic hazard estimation at bedrock level using highly ranked GMPEs are presented in Chapters 4 and 5 respectively. Subsurface lithology, measurement of dynamic soil properties and correlations are essential to assess region specific site effects and liquefaction potential. Discussion on the experimental studies, subsurface profiling using geotechnical and geophysical tests results and correlation between shear wave velocity (SWV) and standard penetration test (SPT) N values are presented in Chapter 6. Detailed shear wave velocity profiling with seismic site classification and ground response parameters considering multiple ground motion data are discussed in Chapters 7 and 8. Chapters 9 and 10 present the assessment of liquefaction potential and determination of hazard index with microzonation maps respectively. Conclusions derived from each chapter are presented in Chapter 11. A brief summary of the work is presented below: Attenuation relations or GMPEs are important component of any seismic hazard analysis which controls accurate prediction of the hazard values. Even though the Himalayas have experienced great earthquakes since ancient times, suitable GMPEs which are applicable for a wide range of distance and magnitude are limited. Most of the available regional GMPEs were developed considering limited recorded data and/or pure synthetic ground motion data. This chapter presents development of a regional GMPE considering both the recorded as well as synthetic ground motions. In total 14 earthquakes consisting of 10 events with recorded data and 4 historic events with Isoseismal maps are used for the same. Synthetic ground motions based on finite fault model have been generated at unavailable locations for recorded events and complete range distances for historic earthquakes. Model parameters for synthetic ground motion were arrived by detailed parametric study and from literatures. A concept of Apparent Stations (AS) has been used to generate synthetic ground motion in a wide range of distance as well as direction around the epicenter. Synthetic ground motion data is validated by comparing with available recorded data and peak ground acceleration (PGA) from Isoseismal maps. A new GMPE has been developed based on two step stratified regression procedure considering the combined dataset of recorded and synthetic ground motions. The new GMPE is validated by comparing with three recently recorded earthquakes events. GMPE proposed in this study is capable of predicting PGA values close to recorded data and spectral acceleration up to period of 2 seconds. Comparison of new GMPE with the recorded data of recent earthquakes shows a good matching of ground motion as well as response spectra. The new GMPE is applicable for wide range of earthquake magnitudes from 5 to 9 on Mw scale. Reduction of future earthquake hazard is possible if hazard values are predicted precisely. A detailed seismic hazard analysis is carried out in this study considering deterministic and probabilistic approaches. New seismotectonic map has been generated for Lucknow considering a radial distance of 350 km around the city centre, which also covers active Himalayan plate boundaries. Past earthquakes within the seismotectonic region have been collected from United State Geological Survey (USGS), Northern California Earthquake Data Centre (NCEDC), Indian Meteorological Department (IMD), Seismic Atlas of India and its Environs (SEISAT) etc. A total of 1831 events with all the magnitude range were obtained. Collected events were homogenized, declustered and filtered for Mw ≥ 4 events. A total of 496 events were found within the seismic study region. Well delineated seismic sources are compiled from SEISAT. Superimposing the earthquake catalogue on the source map, a seismotectonic map of Lucknow was generated. A total of 47 faults which have experienced earthquake magnitude of 4 and above are found which are used for seismic hazard analysis. Based on the distribution of earthquake events on the seismotectonic map, two regions have been identified. Region I which shows high density of seismic events in the area in and around of Main Boundary Thrust (MBT) and Region II which consists of area surrounding Lucknow with sparse distribution of earthquake events. Data completeness analysis and estimation of seismic parameter “a” and “b” are carried out separately for both the regions. Based on the analysis, available earthquake data is complete for a period of 80 years in both the regions. Using the complete data set, the regional recurrence relations have been developed. It shows a “b” value of 0.86 for region I and 0.9 for Region II which are found comparable with earlier studies. Maximum possible earthquake magnitude in each source has been estimated using observed magnitude and doubly truncated Gutenberg-Richter relation. The study area of Lucknow is divided into 0.015o x 0.015o grid size and PGA at each grid has been estimated by considering all sources and the three GMPEs. A Matlab code was generated for seismic hazard analysis and maximum PGA value at each grid point was determined and mapped. Deterministic seismic hazard analysis (DSHA) shows that maximum expected PGA values at bedrock level varies from 0.05g in the eastern part to 0.13g in the northern region. Response spectrum at city centre is also developed up to a period of 2 seconds. Further, Probabilistic seismic hazard analysis (PSHA) has been carried out and PGA values for 10 % and 2 % probability of exceedence in 50 years have been estimated and mapped. PSHA for 10 % probability shows PGA variation from 0.035g in the eastern parts to 0.07g in the western and northern parts of Lucknow. Similarly PSHA for 2 % probability of exceedence indicates PGA variation from 0.07g in the eastern parts while the northern parts are expecting PGA of 0.13g. Uniform hazard spectra are also developed for 2 % and 10 % probability for a period of up to 2 seconds. The seismic hazard analyses in this study show that the northern and western parts of Lucknow are more vulnerable when compared to other part. Bedrock hazard values completely change due to subsoil properties when it reaches the surface. A detailed geophysical and geotechnical investigation has been carried out for subsoil profiling and seismic site classification. The study area has been divided into grids of 2 km x 2 km and roughly one geophysical test using MASW (Multichannel Analysis Surface Wave) has been carried out in each grid and the shear wave velocity (SWV) profiles of subsoil layers are obtained. A total of 47 MASW tests have been carried out and which are uniformly distributed in Lucknow. In addition, 12 boreholes have also been drilled with necessary sampling and measurement of N-SPT values at 1.5 m interval till a depth of 30 m. Further, 11 more borelog reports are collected from the same agency hired for drilling the boreholes. Necessary laboratory tests are conducted on disturbed and undisturbed soil samples for soil classification and density measurement. Based on the subsoil informations obtained from these boreholes, two cross-sections up to a depth of 30 m have been generated. These cross-sections show the presence of silty sand in the top 10 m at most of the locations followed by clayey sand of low to medium compressibility till a depth of 30 m. In between the sand and clay traces of silt were also been found in many locations. In addition to these boreholes, 20 deeper boreholes (depth ≥150 m) are collected from Jal Nigam (Water Corporation) Lucknow, Government of Uttar Pradesh. Typical cross-section along the alignment of these deeper boreholes has been generated up to 150 m depth. This cross-section shows the presence of fine sand near Gomati while other locations are occupied by surface clayey sand. Also, the medium sand has been found in the western part of the city at a depth of 110 m which continues till 150 m depth. On careful examination of MASW and boreholes with N-SPT, 17 locations are found very close and SWV and N-SPT values are available up to 30 m depth. These SWV and N-SPT values are complied and used to develop correlations between SWV and N-SPT for sandy soil, clayey soil and all soil types. This correlation is the first correlation for IGB soil deposits considered measured data up to 30 m. The new correlation is verified graphically using normal consistency ratio and standard percentage error with respect to measured N-SPT and SWV. Further, SWV and N-SPT profiles are used Another important earthquake induced hazard is liquefaction. Even though many historic earthquakes caused liquefaction in India, very limited attempt has been made to map liquefaction potential in IGB. In this study, a detailed liquefaction analysis has been carried out for Lucknow a part of Ganga Basin to map liquefaction potential. Initially susceptibility of liquefaction for soil deposits has been assessed by comparing the grain size distribution curve obtained from laboratory tests with the range of grain size distribution for potentially liquefiable soils. Most of surface soil deposits in the study area are susceptible to liquefaction. At all the 23 borehole locations, measured N-SPT values are corrected for (a) Overburden Pressure (CN), (b) Hammer energy (CE), (c) Borehole diameter (CB), (d) presence or absence of liner (CS), (e) Rod length (CR) and (f) fines content (Cfines). Surface PGA values at each borehole locations are used to estimate Cyclic Stress Ratio (CSR). Corrected N-SPT values [(N1)60CS] are used to estimate Cyclic Resistance Ratio (CRR) at each layer. CSR and CRR values are used to estimate Factor of Safety (FOS) against liquefaction in each layer. Least factor safety values are indentified from each location and presented liquefaction factor of safety map for average and maximum amplified PGA values. These maps highlight that northern, western and central parts of Lucknow are very critical to critical against liquefaction while southern parts shows moderate to low critical area. The entire alignment of river Gomati falls in very critical to critical regions for liquefaction. Least FOS shows worst scenario and does not account thickness of liquefiable soil layers. Further, these FOS values are used to determine Liquefaction Potential Index (LPI) of each site and developed LPI map. Based on LPI map, the Gomati is found as high to very high liquefaction potential region. Southern and the central parts of Lucknow show low to moderate liquefaction potential while the northern and western Lucknow has moderate to high liquefaction potential. All possible seismic hazards maps for Lucknow have been combined to develop final microzonation map in terms of hazard index values. Hazard index maps are prepared by combining rock PGA map, site classification map in terms of shear wave velocity, amplification factor map, and FOS map and predominant period map by adopting Analytical Hierarchy Process (AHP). All these parameters have been given here in the order starting with maximum weight of 6 for PGA to lower weight of 1 for predominant frequency. Normalized weights of each parameter have been estimated. Depending upon the variation of each hazard parameter values, three to five ranks are assigned and the normalized ranks are calculated. Final hazard index values have been estimated by multiplying normalized ranks of each parameter with the normalized weights. Microzonation map has been generated by mapping hazard index values. Three maps were generated based on DSHA, PSHA for 2% and 10 % probability of exceedence in 50 years. Hazard index maps from DSHA and PSHA for 2 % probability show similar pattern. Higher hazard index were obtained in northern and western parts of Lucknow and lower values in others. The new microzonation maps can help in dividing the Lucknow into three parts as high area i.e. North western part, moderate hazard area i.e. central part and low hazard area which covers southern and eastern parts of Lucknow. This microzonation is different from the current seismic code where all area is lumped in one zone without detailed assessment of different earthquake hazard parameters. Finally this study brings out first region specific GMPE considering recorded and synthetic ground monitions for wide range of magnitudes and distances. Proposed GMPE can also be used in other part of the Himalayan region as it matches well with the highly ranked GMPEs. Detailed rock level PGA map has been generated for Lucknow considering DSHA and PSHA. A detailed geotechnical and geophysical experiments are carried out in Lucknow. These results are used to develop correction between SWV and N-SPT values for soil deposit in IGB and site classification maps for the study area. Amplification and liquefaction potential of Lucknow are estimated by considering multiple ground motions data to account different earthquake ground motion amplitude, duration and frequency, which is unique in the seismic microzonation study.

The objective of this study is to evaluate the regional differences between the worldwide based NGA-W1 ground motion models and available Turkish strong ground motion dataset and make the required adjustments in the NGA-W1 models. A strong motion dataset using parameters consistent with the NGA ground motion models is developed by including strong motion data from Turkey. Average horizontal component ground motion is computed for response spectral values at all available periods using the GMRotI50 definition consistent with the NGA-W1 models. A random-effects regression with a constant term only is used to evaluate the systematic differences in the average level of shaking. Plots of residuals are used to evaluate the differences in the magnitude, distance, and site amplification scaling between the Turkish dataset and the NGA-W1 models. Model residuals indicated that the ground motions are overestimated by all 5 NGA-W1 models significantly, especially for small-to-moderate magnitude earthquakes. Model residuals relative to distance measures plots suggest that NGA-W1 models slightly underestimates the ground motions for rupture distances within 100-200 km range. Models including the aftershocks over-predict the ground motions at stiff soil/engineering rock sites. The misfit between the actual data and model predictions are corrected with adjustments functions for each scaling term. Turkey-Adjusted NGA-W1 models proposed in this study are compatible with the Turkish strong ground motion characteristics and preserve the well-constrained features of the global models. Therefore these models are suitable candidates for ground motion characterization and PSHA studies conducted in Turkey.

Vertical design spectra may be developed in a probabilistic seismic hazard assessment (PSHA) by computing the hazard using vertical ground motion prediction equations (GMPEs), or using a vertical-to-horizontal spectral acceleration (V/H) ratio GMPEs to scale the horizontal spectrum that was developed using the results of horizontal component PSHA. The objective of this study is to provide GMPEs that are compatible with regional ground motion characteristics to perform both alternatives. GMPEs for the V/H ratio were developed recently by G&uuml / lerce and Abrahamson (2011) using NGA-W1 database. A strong motion dataset consistent with the V/H ratio model parameters is developed by including strong motion data from earthquakes occurred in Turkey with at least three recordings per earthquake. The compatibility of GA2011 V/H ratio model with the magnitude, distance, and site amplification scaling of Turkish ground motion dataset is evaluated by using inter-event and intra-event residual plots and necessary coefficients of the model is adjusted to reflect the regional characteristics. Analysis of the model performance in the recent moderate-tolarge magnitude earthquakes occurred in Turkey shows that the Turkey-Adjusted GA2011 model is a suitable candidate V/H ratio model for PSHA studies conducted in Turkey. Using the same dataset, a preliminary vertical ground motion prediction equation for Turkey consistent with the preliminary vertical model based on NGA-W1 dataset is developed. Proposed preliminary model is applicable to magnitudes 5-8.5, distances 0-200 km, and spectral periods of 0-10 seconds and offers an up-to-date alternative to the regional vertical GMPEs proposed by Kalkan and G&uuml / lkan (2004).

Bolu-Ilgaz region was damaged by several large earthquakes in the last century and the structural damage was substantial especially after the 1944 and 1999 earthquakes. The objective of this study is to build the seismic source characterization model for the rupture zone of 1944 Bolu-Gerede earthquake and perform probabilistic seismic hazard assessment (PSHA) in the region. One of the major improvements over the previous PSHA practices accomplished in this study is the development of advanced seismic source models in terms of source geometry and reoccurrence relations. Geometry of the linear fault segments are determined and incorporated with the help of available fault maps. Composite magnitude distribution model is used to properly represent the characteristic behavior of NAF without an additional background zone. Fault segments, rupture sources, rupture scenarios and fault rupture models are determined using the WG-2003 terminology. The Turkey-Adjusted NGAW1 (G&uuml / lerce et al., 2013) prediction models are employed for the first time on NAF system. The results of the study is presented in terms of hazard curves, deaggregation of the hazard and uniform hazard spectrum for four main locations in the region to provide basis for evaluation of the seismic design of special structures in the area. Hazard maps of the region for rock site conditions and for the proposed site characterization model are provided to allow the user perform site-specific hazard assessment for local site conditions and develop site-specific design spectrum. The results of the study will be useful to manage the future seismic hazard in the region.

Earthquake-induced slope instability is one of the major sources of earthquake hazards in near fault regions. Simplified tools, such as Newmark&rsquo / s Sliding Block (NSB) Analysis are widely used to represent the stability of a slope under earthquake shaking. The outcome of this analogy is the slope displacement where larger displacement values indicate higher seismic slope instability risk. Recent studies in the literature propose empirical models between the slope displacement and single or multiple ground motion intensity measures such as peak ground acceleration or Arias intensity. These correlations are based on the analysis of large datasets from global ground motion recording database (PEER NGA-W1 Database). Ground motions from earthquakes occurred in Turkey are poorly represented in NGA-W1 database since corrected and processed data from Turkey was not available until recently. The objective of this study is to evaluate the compatibility of available NSB displacement prediction models for the Probabilistic Seismic Hazard Assessment (PSHA) applications in Turkey using a comprehensive dataset of ground motions recorded during earthquakes occurred in Turkey. Then the application of selected NSB displacement prediction model in a vector-valued PSHA framework is demonstrated with the explanations of seismic source characterization, ground motion prediction models and ground motion intensity measure correlation coefficients. The results of the study is presented in terms of hazard curves and a comparison is made with a case history in Asarsuyu Region where seismically induced landslides (Bakacak Landslides) had taken place during 1999 D&uuml / zce Earthquake.

The primary objective of this study is to evaluate the seismic hazard in the Eastern Marmara Region using improved seismic source models and enhanced ground motion prediction models by probabilistic approach. Geometry of the fault zones (length, width, dip angle, segmentation points etc.) is determined by the help of available fault maps and traced source lines on the satellite images. State of the art rupture model proposed by USGS Working Group in 2002 is applied to the source system. Composite reoccurrence model is used for all seismic sources in the region to represent the characteristic behavior of North Anatolian Fault. New and improved global ground motion models (NGA models) are used to model the ground motion variability for this study. Previous studies, in general, used regional models or older ground motion prediction models which were updated by their developers during the NGA project. New NGA models were improved in terms of additional prediction parameters (such as depth of the source, basin effects, site dependent standard deviations, etc.), statistical approach, and very well constrained global database. The use of NGA models reduced the epistemic uncertainty in the total hazard incorporated by regional or older models using smaller datasets. The results of the study is presented in terms of hazard curves, deaggregation of the hazard and uniform hazard spectrum for six main locations in the region (Adapazari, Duzce, Golcuk, Izmit, Iznik, and Sapanca City Centers) to provide basis for seismic design of special structures in the area. Hazard maps of the region for rock site conditions at the accepted levels of risk by Turkish Earthquake Code (TEC-2007) are provided to allow the user perform site-specific hazard assessment for local site conditions and develop site-specific design spectrum. Comparison of TEC-2007 design spectrum with the uniform hazard spectrum developed for selected locations is also presented for future reference.

The North Anatolian Fault System is one of the most important active strike-slip fault systems in the world. The August 17, 1999 and November 12, 1999 earthquakes at Kocaeli and D&uuml / zce are the most recent devastating earthquakes. The study area lies in the Eastern Marmara Region and is bounded by the 28.55-33.75 E and 40.00-41.20 N, latitude and longitude coordinates, respectively. There are numerous studies conducted in the study area in terms of active tectonics and seismicity, however studies are scale dependent. Therefore, a comprehensive literature survey regarding active tectonics of the region was conducted and these previous studies were combined with the lineaments extracted from 10 ASTER images via principle component analysis manual extraction method. Therefore, a line seismic source model for the Eastern Marmara region was compiled mainly based on major seismic events of instrumental period. The seismicity of these line segments were compared with the instrumental period earthquake catalogue compiled by Kandilli Observatory and Earthquake Research Institute with a homogeneous magnitude scale between 1900 and 2005. Secondary event and completeness of this catalogue was checked. The final catalogue was matched with the compiled seismic source for historical seismicity and source-scenario-segment-weight relationships were developed. This developed seismic source model was tested by a probabilistic seismic hazard assessment for D&uuml / zce city center by utilizing four different ground motion prediction equations. It was observed that Gutenberg-Richter seismicity parameter &lsquo / b&rsquo / does not have significant effect over the model, however change in the segmentation model have a low but certain influence.

Earthquakes are among the most devastating and unpredictable of natural hazards that affect civil infrastructure and have the potential for causing numerous casualties and significant economic losses over large areas. Every region that has the potential for great earthquakes should have an integrated plan for a seismic design and risk mitigation for civil infrastructure. This plan should include methods for estimating the vulnerability of building inventories and for forecasting economic losses resulting from future events. This study describes a methodology to assess risk to distributed civil infrastructure due to large-scale natural hazards with large geographical footprints, such as earthquakes, hurricanes and floods, and provides a detailed analysis and assessment of building losses due to earthquake. The distinguishing feature of this research, in contrast to previous loss estimation methods incorporated in systems such as HAZUS-MH, is that it considers the correlation in stochastic demand on building inventories due to the hazard, as well as correlation in building response and damage due to common materials, construction technologies, codes and code enforcement. These sources of correlation have been neglected, for the most part, in previous research. The present study has revealed that the neglect of these sources of correlation leads to an underestimation of the estimates of variance in loss and in the probable maximum loss (PML) used as a basis for underwriting risks. The methodology is illustrated with a seismic risk assessment of building inventories representing different occupancy classes in Shelby County, TN, considering both scenario earthquakes and earthquakes specified probabilistically. It is shown that losses to building inventories estimated under the common assumption that the individual losses can be treated as statistically independent may underestimate the PML by a factor of range from 1.7 to 3.0, depending on which structural and nonstructural elements are included in the assessment. A sensitivity analysis reveals the statistics and sources of correlation that are most significant for loss estimation, and points the way forward for supporting data acquisition and synthesis.

Seismic hazard and microzonation of cities enable to characterize the potential seismic areas that need to be taken into account when designing new structures or retrofitting the existing ones. Study of seismic hazard and preparation of geotechnical microzonation maps will provide an effective solution for city planning and input to earthquake resistant design of structures in an area. Seismic hazard is the study of expected earthquake ground motions at any point on the earth. Microzonation is the process of sub division of region in to number of zones based on the earthquake effects in the local scale. Seismic microzonation is the process of estimating response of soil layers under earthquake excitation and thus the variation of ground motion characteristic on the ground surface. Geotechnical site characterization and assessment of site response during earthquakes is one of the crucial phases of seismic microzonation with respect to ground shaking intensity, attenuation, amplification rating and liquefaction susceptibility. Microzonation mapping of seismic hazards can be expressed in relative or absolute terms, on an urban block-by-block scale, based on local soil conditions (such as soil types) that affect ground shaking levels or vulnerability to soil liquefaction. Such maps would provide general guidelines for integrated planning of cities and in positioning the types of new structures that are most suited to an area, along with information on the relative damage potential of the existing structures in a region. In the present study an attempt has been made to characterize the site and to study the seismic hazard analysis considering the local site effects and to develop microzonation maps for Bangalore. Seismic hazard analysis and microzonation of Bangalore is addressed in this study in three parts: In the first part, estimation of seismic hazard using seismotectonic and geological information. Second part deals about site characterization using geotechnical and shallow geophysical techniques. An area of 220 sq.km, encompassing Bangalore Municipal Corporation has been chosen as the study area in this part of the investigation. There were over 150 lakes, though most of them are dried up due to erosion and encroachments leaving only 64 at present in an area of 220 sq. km and emphasizing the need to study site effects. In the last part, local site effects are assessed by carrying out one-dimensional (1-D) ground response analysis (using the program SHAKE 2000) using both borehole SPT data and shear wave velocity survey data within an area of 220 sq. km. Further, field experiments using microtremor studies have also been carried out (jointly with NGRI) for evaluation of predominant frequency of the soil columns. The same has been assessed using 1-D ground response analysis and compared with microtremor results. Further, Seed and Idriss simplified approach has been adopted to evaluate the liquefaction susceptibility and liquefaction resistance assessment. Microzonation maps have been prepared for Bangalore city covering 220 sq. km area on a scale of 1:20000. Deterministic Seismic Hazard Analysis (DSHA) for Bangalore has been carried out by considering the past earthquakes, assumed subsurface fault rupture lengths and point source synthetic ground motion model. The seismic sources for region have been collected by considering seismotectonic atlas map of India and lineaments identified from satellite remote sensing images. Analysis of lineaments and faults help in understanding the regional seismotectonic activity of the area. Maximum Credible Earthquake (MCE) has been determined by considering the regional seismotectonic activity in about 350 km radius around Bangalore. Earthquake data are collected from United State Geological Survey (USGS), Indian Metrological Department (IMD), New Delhi; Geological Survey of India (GSI) and Amateur Seismic Centre (ASC), National Geophysical Research Institute (NGRI),Hyderabad; Centre for Earth Science Studies (CESS), Akkulam, Kerala; Gauribindanur (GB) Seismic station and other public domain sites. Source magnitude for each source is chosen from the maximum reported past earthquake close to that source and shortest distance from each source to Bangalore is arrived from the newly prepared seismotectonic map of the area. Using these details, and, attenuation relation developed for southern India by Iyengar and Raghukanth (2004), the peak ground acceleration (PGA) has been estimated. A parametric study has been carried out to find fault subsurface rupture length using past earthquake data and Wells and Coppersmith (1994) relation between the subsurface lengths versus earthquake magnitudes. Further seismological model developed by Boore (1983, 2003) SMSIM program has been used to generate synthetic ground motions from vulnerable sources identified in above two methods. From the above three approaches maximum PGA of 0.15g was estimated for Bangalore. This value was obtained for a maximum credible earthquake (MCE) having a moment magnitude of 5.1 from a source of Mandya-Channapatna-Bangalore lineament. Considering this lineament and MCE, a synthetic ground motion has been generated for 850 borehole locations and they are used to prepare PGA map at rock level. The past seismic data has been collected for almost 200 years from different sources such as IMD, BARC (Gauribidanur array), NGRI, CESS, ASC center, USGS, and other public domain data. The seismic data is seen to be homogenous for the last four decades irrespective of the magnitude. Seismic parameters were then evaluated using the data corresponding to the last four decades and also the mixed data (using Kijko’s analysis) for Bangalore region, which are found to be comparable with the earlier reported seismic parameters for south India. The probabilities of distance, magnitude and peak ground acceleration have been evaluated for the six most vulnerable sources using PSHA (Probabilistic Seismic Hazard Analysis). The mean annual rate of exceedance has been calculated for all the six sources at the rock level. The cumulative probability hazard curves have been generated at the bedrock level for peak ground acceleration and spectral acceleration. The spectral acceleration calculation corresponding to a period of 1sec and 5% damping are evaluated. For the design of structures, uniform hazard response spectrum (UHRS) at rock level is developed for the 5% damping corresponding to 10% probability of exceedance in 50 years. The peak ground acceleration (PGA) values corresponding to 10% probability of exceedance in 50 years are comparable to the PGA values obtained in deterministic seismic hazard analysis (DSHA) and higher than Global Seismic Hazard Assessment Program (GSHAP) maps of Bhatia et.al (1997) for the Indian shield area. The 3-D subsurface model with geotechnical data has been generated for site characterization of Bangalore. The base map of Bangalore city (220sq.km) with several layers of information (such as Outer and Administrative boundaries, Contours, Highways, Major roads, Minor roads, Streets, Rail roads, Water bodies, Drains, Landmarks and Borehole locations) has been generated. GIS database for collating and synthesizing geotechnical data available with different sources and 3-dimensional view of soil stratum presenting various geotechnical parameters with depth in appropriate format has been developed. In the context of prediction of reduced level of rock (called as “engineering rock depth” corresponding to about Vs > 700 m/sec) in the subsurface of Bangalore and their spatial variability evaluated using Artificial Neural Network (ANN). Observed SPT ‘N’ values are corrected by applying necessary corrections, which can be used for engineering studies such as site response and liquefaction analysis. Site characterization has also been carried out using measured shear wave velocity with the help of shear wave velocity survey using MASW. MASW (Multichannel Analysis of Surface Wave) is a geophysical method, which generates a shear-wave velocity (Vs) profile (i.e., Vs versus depth) by analyzing Raleigh-type surface waves on a multichannel record. MASW system consisting of 24 channels Geode seismograph with 24 geophones of 4.5 Hz capacity were used in this investigation. The shear wave velocity of Bangalore subsurface soil has been measured and correlation has been developed for shear wave velocity (Vs) with the standard penetration tests (SPT) corrected ‘N’ values. About 58 one-dimensional (1-D) MASW surveys and 20 two-dimensional (2-D) MASW surveys has been carried out with in 220 sq.km Bangalore urban area. Dispersion curves and shear velocity 1-D and 2-D have been evaluated using SurfSeis software. Using 1-dimensional shear wave velocity, the average shear wave velocity of Bangalore soil has been evaluated for depths of 5m, 10m, 15m, 20m, 25m and 30m (Vs30) depths. The sub soil classification has been carried out for local site effect evaluation based on average shear wave velocity of 30m depth (Vs30) of sites using NEHRP (National Earthquake Hazard Research Programme) and IBC (International Building Code) classification. Bangalore falls into site class D type of soil. Mapping clearly indicates that the depth of soil obtained from MASW is closely matching with the soil layers in the bore logs. The measured shear wave velocity at 38 locations close to SPT boreholes, which are used to generate the correlation between the shear wave velocity and corrected ‘N’ values using a power fit. Also, developed relationship between shear wave velocity and corrected ‘N’ values corresponds well with the published relationships of Japan Road Association. Bangalore city, a fast growing urban center, with low to moderate earthquake history and highly altered soil structure (due to large reclamation of land) is been the focus of this work. There were over 150 lakes, though most of them are dried up due to erosion and encroachments leaving only 64 at present in an area of 220 sq km. In the present study, an attempt has been made to assess the site response using geotechnical, geophysical data and field studies. The subsurface profiles of the study area within 220sq.km area was represented by 170 geotechnical bore logs and 58 shear wave velocity profiles obtained by MASW survey. The data from these geotechnical and geophysical technique have been used to study the site response. These soil properties and synthetic ground motions for each borehole locations are further used to study the local site effects by conducting one-dimensional ground response analysis using the program SHAKE2000. The response and amplification spectrum have been evaluated for each layer of borehole location. The natural period of the soil column, peak spectral acceleration and frequency at peak spectral acceleration of each borehole has been evaluated and presented as maps. Predominant frequency obtained from both methods is compared; the correlation between corrected SPT ‘N’ value and low strain shear modulus has been generated. The noise was recorded at 54 different locations in 220sq.km area of Bangalore city using L4-3D short period sensors (CMG3T) equipped with digital data acquisition system. Predominant frequency obtained from ground response studies and microtremor measurement is comparable. To study the liquefaction hazard in Bangalore, the liquefaction hazard assessment has been carried out using standard penetration test (SPT) data and soil properties. Factor of Safety against liquefaction of soil layer has been evaluated based on the simplified procedure of Seed and Idriss (1971) and subsequent revisions of Seed et al (1983, 1985), Youd et al (2001) and Cetin et al (2004). Cyclic Stress Ratio (CSR) resulting from earthquake loading is calculated by considering moment magnitude of 5.1 and amplified peak ground acceleration. Cyclic Resistant Ratio (CRR) is arrived using the corrected SPT ‘N’ values and soil properties. Factor of safety against liquefaction is calculated using stress ratios and accounting necessary magnitude scaling factor for maximum credible earthquake. A simple spread sheet was developed to carryout the calculation for each bore log. The factor of safety against liquefaction is grouped together for the purpose of classification of Bangalore (220 sq. km) area for a liquefaction hazards. Using 2-D base map of Bangalore city, the liquefaction hazard map was prepared using AutoCAD and Arc GIS packages. The results are grouped as four groups for mapping and presented in the form of 2-dimensional maps. Liquefaction possibilities are also assessed conducting laboratory cyclic triaxial test using undisturbed soil samples collected at few locations.

Viti Levu, the main island of Fiji, is located in a seismically active area within the Fiji Platform - a remnant island arc that lies in a diffuse plate boundary zone between the Pacific and Australian tectonic plates in the southwest Pacific. The southeast coast of Viti Levu is a highly developed and populated part of Fiji and is vulnerable to the effects of large earthquakes that are expected to occur both onshore and offshore. The structural framework and the origin of seismicity within the Fiji Platform, as well as the seismic and tsunami hazards of central and southeast Viti Levu are investigated. The upper crust of southeast Viti Levu is dissected by several intersecting fault/lineament zones. These are mapped from remote sensing imagery of the surface (topography, radar, and aerial photos) and of the basement (magnetic), and have been subject to rigorous statistical tests of reproducibility and verification with field mapped fault data. Lineaments on the various imagery correlate with faults mapped in the field and show spatial continuity between and beyond mapped faults, thereby providing a fuller coverage of regional structural patterns than previously known. Some fault/lineament zones extend beyond the coastline to the offshore area of southeast Viti Levu. Here high resolution SeaBAT 8160 multibeam bathymetry data and seismic reflection data show that the fault zones occur along, and exert control on the locations of a number of linear submarine canyons. The morpho-structural expression of these canyons are contiguous with fault controlled physiographic features mapped on the nearshore marginal shelf (rectilinear bays and peninsulas, reef passages) and on land (fault valleys, slope and drainage alignments forming lineaments). The canyons are considered to have developed from several cycles of downslope incising and infilling events, whilst their positions were still primarily controlled by zones of weakness created by the fault zones. The principal fault sets in southeast Viti Levu represent generations of regional tectonic faulting that pervaded the Fiji Platform during and after disruption of the proto Fijian arc in the Middle to Late Miocene. These fault sets combine to form a complex network of interlocking faults creating a fault mesh that divides the upper crust into a number of fault blocks ranging from ~2 to 30 km. It is inferred that the fault mesh evolved throughout the Neogene as a response to the anticlockwise rotation of the Fiji Platform through progressive development of different fault sets and intervening crustal block rotations. Regional tectonic deformation is presently accommodated in a distributed manner through the entire fault mesh. Low magnitude earthquakes (<M4) occur regularly and may represent ruptures along short linking segments of the fault mesh, while infrequent larger earthquakes (>M4) may result from complex rupture propagation through several linking fault segments of the mesh that lie close to optimum stress orientations. This interpreted model of distributed deformation through the fault mesh for southeast Viti Levu is inferred to be characteristic of the style of active deformation that occurs throughout the entire Fiji Platform. Seismic activity is primarily responsible for triggering submarine landslides that occur on the southeastern slope of Viti Levu. These slides typically occur on the outer barrier reef edge, as well as in submarine canyon heads and walls, and in the mid slope areas. They are characteristically translational and lack bathymetric evidence for displaced masses. Morphometric analysis and empirical modelling, show that slides triggered at shallow water depths, within 5 km of the coastline, at the outer barrier reef edge and submarine canyon heads, produce the largest near-field tsunami amplitudes. Such slides are interpreted to represent a significant local tsunami hazard. A detailed case study of the destructive 1953 Suva tsunami that followed the Ms 6.75 Suva earthquake, reveals that the source of this tsunami was a 60 million cubic metre submarine landslide at the head of the Suva Canyon, 4 km to the WSW of Suva City. A test simulation of this tsunami using the Geowave tsunami generation, propagation and inundation model, closely replicates the wave heights and arrival times recorded in 1953. This simulation also reveals that high variability in tsunami impact over short coastal distances of southeast Viti Levu is attributable to the complex interplay of wave propagation with the barrier reef system, erratic lagoon bathymetry and the irregularly shaped coastline. A predictive simulation using Geowave, based on an incipient failure in the 1953 source area and on a potentially worse case scenario event at or near high-tide, is used to show a maximum vertical run up of at least 4 m and a maximum horizontal inundation level of at least 400 m at the Suva coast. The seismic hazard of five sites on Viti Levu, including Suva City, Navua and Nausori Towns, and the Monsavu and Nadarivatu dam sites, is evaluated using a deterministic approach, and seven newly identified crustal fault earthquake source structures. The maximum magnitudes interpreted for these structures, estimated using empirical relationships, range from Mw 6.8 to 7.6. The Suva Canyon Fault, the Naqara Fault, the Mavuvu/Fault Lineament Zone and the Nasivi Fault provide the controlling maximum credible earthquakes (CMCE) at all the five sites. The CMCE peak ground acceleration values for Suva City range from 0.4g to 0.6g, for Nausori Town from 0.18g to 0.2g, for Navua Town from 0.27g to 0.32g, for Monasavu from 0.39g to 0.42g, and for Nadarivatu from 0.23g to 0.33g. The horizontal spectral accelerations at a period equal to 0.2 seconds, calculated using the CMCEs, are comparable to accelerations derived by probabilistic methods that have return periods between 50 and over 1000 years.