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Principles and Practices of Seismic Microzonation: Some case Studies in India

T.G. Sitharam, Professor of Geotechnical Engineering and Chairman, CiSTUP, Department of Civil Engineering, Indian Institute of Science, Bangalore, India, 560012. email - [email protected],

ABSTRACT In the recent past, large earthquakes have caused massive loss of lives and extensive physical destruction throughout the world (Armenia, 1988; Iran, 1990; US, 1994; Japan, 1995; Turkey, 1999; Taiwan, 1999, India 2001, Sumatra 2004, Pakistan, 2005, China 2008). On January 26, 2001 Bhuj Earthquake, one of the most destructive earthquakes ever to strike India occurred in the Kachchh region of Gujarat in western India. Bhuj earthquake of 2001 was of magnitude 7.7 (Mw) and the damage wide was spread over a radius of 350kms including major cities like Ahmedabad, Bhavnagar and Surat at a distance of 240 km, 275 km and 350 km respectively. The damage incurred in an earthquake depends not only on the size of the earthquake magnitude (source) but also, to a large extent, on the medium through which the seismic waves propagate (path and site effects) and the socio-economic development of the human settlement (Panza et al., 2001). Many big cities in India are situated in the severe earthquake hazard threat in the vicinity of Himalayan region and even in peninsular shield. Macrozonation map in Indian seismic code 1893 is frequently revised soon after a major earthquake. New revision was published in 2002 after Bhuj earthquake in 2001, which contains four macro zones. These zones are based on geology and limited seismological input without considering geotechnical aspects of site effects and liquefaction. To mitigate the seismic hazard, it is necessary to define a ground response in terms of both the peak ground acceleration and spectral amplification. India has two types of earthquakes distribution: irregular occurrence of earthquake in Peninsular India and regular occurrence of earthquake in northern, northeastern, and the northwestern part of India (on the plate boundaries). Earthquake in Peninsular India are intraplate earthquakes and earthquakes in other parts are intraplate as well as interplate earthquake due to collision of boundary of the Eurasian and Indian plate. Several cities like Delhi, Mumbai, Kolkata, Dehradun, Guwahati and many other cities which have large population are sitting in thick sedimentary basins along IndoGangetic plane and Bramhaputra valley. To mitigate the seismic hazard, it is necessary to define a ground response at the surface in terms of both the peak ground acceleration and spectral amplification, which are highly dependent on the local soil conditions and on the source characterization of the expected earthquakes. The present study presents a review on the development of the seismic microzonation studies. Seismic microzonation work has been carried out in India in some of the important mega cities that have the potential of being damaged from future earthquakes. In order to understand the earthquake vulnerability of major urban centers, the Govt. of India has initiated microzonation of 63 cities in India after 2001 earthquake. Many microzonation studies are under progress and some of them have been completed. This paper presents overview of these studies. Seismic microzonation of Jabalpur urban area is the first work in India towards seismic microzonation of Indian cities. Preliminary microzonation of Delhi has been completed and detailed one with scale of 1:10000 is under progress. Seismic Hazard and Microzonation Atlas of the Sikkim Himalaya was published with geological and seismological background. Microzonation of Guwahati maps have been prepared based on geology and geomorphology, seismotectonics, soil characteristics, pre-dominant frequencies, peak ground acceleration, seismic hazard, demography and preliminary risk. Seismic Microzonation of Dehradun has been prepared based on shear wave velocity with site response. First order microzonation of Haldia was developed based on peak ground acceleration, predominant frequency and elevation map.

Different maps and results are presented for Gujarat microzonation based on noise survey and after shock data. None of these studies have considered detailed geotechnical aspects such as site effects, liquefaction and landslides. In this paper, the microzonation studies carried out in different cities of India with different methodologies used by various researchers will be discussed. Further, the merits and limitations of these studies have also been highlighted. Seismic microzonation studies in India lack few aspects/issues which can be broadly classified into three groups: 1) seismology related, 2) grade and geology related and 3) geotechnical related issues. Most of microzonation studies do not have proper regional seismotectonic maps for the study area. Seismic microzonation maps published are based on deterministic seismic hazard analysis for different possible scenario earthquakes. This may be improved by considering uncertainties involved in the earthquake and produce the hazard map with required probability and return periods. Seismic microzonation maps produced does not have a uniform scale, which may be generalized under the uniform grade and scale of mapping. Importance of geology plays a major role in microzonation studies in India, which is inadequate to represent local site effects. More importance shall be given to geotechnical aspects in seismic microzonation studies. Keywords: Seismic microzonation, hazard, site characterization, site response study, liquefaction

Tectonic geomorphology as a tool for Paleoseismic studies: A Case Study of Alaknanda Valley, Uttarakhand Himalaya, India S. P. Sati' , Naresh Rana'. Devender Kumar and D. V. Reddy" 'Department of Geology (Mountain Science). HNB Garhwal University, Srinagar, Garhwal "National Geophysical research Institute, Hyderabad. Email: [email protected]

Himalaya is one the seismically most active zone of the world. Since its origin to present day it is in persistent state of stress due to the continuous northward drift of the Indian plate. This stress many times released in the form of minor tremor to devastating earthquake. The most devastating among these; 1905 Kangra Earthquke. 1934 Bihar-Nepal earthquake, 1950 Assam earthquake and 2004 Kashmir earthquake are well known. Alakiianda valley comprises a great and tectonically very important part of the Garhwal Himalaya.. Several tectonically important major and minor structures pass through this valley making it vulnerable for landslide and earthquakes. Garhwa] Himalaya has evidenced 37 seismic events during 1803 -1999 of magnitude greater than 5 including two large earthquake events of in 1803 and 1833 and faces a continuous panic due to the landslide every year. Paleoseismology is the study of the prehistoric earthquake and provide and account of the style, size, timing and recurrence of the past earthquakes. Hence it provides important information and the database for the Earthquake hazards zonation of an area. To search and analyze the signatures of these and many more past earthquakes is always a difficult task particularly in case of Himalayan terrain. Alaknanda valley, he area of present study that falls in the Central Himalaya is not the exception. Though at the several localities of the whole basin, huge piles of alluvial deposits are locked but they hardly consist any convincing seismite features. In present study, to analyze and document signatures of past earthquakes, we adopted somewhat unconventional approach i.e., we focused our attention on geomorphic expressions of the deformational feature which we suspect are born as a result of past earthquake events. The field observations are supported by chronological data obtained using the OSL dating techniques.

Current seismic hazard scenario in Garhwal-Kumaun Himalayas Ajay Paul Wadia Institute of Himalayan Geology, Dehradun (E-mail: [email protected]) Abstract Garhwal-Kumaun Himalayas lies in zone iv and v of the seismic zoning map of India (IS; 1893-1984). GPS data reveals that strain energy is being continuously accumulating but no great earthquake has occurred in the last one hundred fifty years in this region. Wadia Institute of Himalayan Geology has deployed a VSAT linked broad band seismic network in July 07 comprising of one Central Recording Station (CRS) at Dehradun and ten remote stations, to monitor local and regional seismic activity of this region. The data is received in real time at CRS and the seismicity is monitored on daily basis. The present paper incorporates the analysis of five hundred eighty four local events of magnitude ranging between 1.5 and 4.9 and depth 10-25 km recorded between July 07 and May 09. The epicentral location map indicates that region south of MCT is more active. Present scenario of seismic hazard has been evaluated on the basis of the contour map drawn from the recorded peak ground accelerations(PGA) for the events of M > 2.5. The regions around Uttarkashi and Chamoli are showing comparatively higher PGA values. Also an an attempt has been made to compare these PGA values with the three moderate earthquakes of recent past of this region which have occurred at an interval of 8 yrs. i.e. Uttarkashi earthquake ( 20th October' 1991, ML 6.5 ) Chamoli earthquake ( 29th March 1999, ML 6.6 ) and Kharsali earthquake ( 23rd July 2007, ML 4.9 )

Observation of earth's free oscillations in Gujarat Superconducting Gravimeter at MPGO site Badargadh in Kachchh

Arun Gupta, Rashmi Pradhan, Srichand Prajapati, Mukesh Chauhan and B.K. Rastogi Institute of Seismological Research, Raisan, Gandhinagar-382 009 Abstract

Magnitude 5 earthquakes are still occurring in Kachchh occasionally and 70 shocks of magnitude >1 on an average per month One Multi-parametric Geophysical Observatory (MPGO) has been established at Badargadh which falls in aftershock zone of 2001 Bhuj earthquake (Mw 7.7). Besides other MPGO instruments, a very sensitive dual sphere superconducting gravimeter (SG) is installed in March 2009 at Badargadh. Tonga region earthquake (M 7.6) occurred on March 19, 2009 excited the earth's free oscillations almost immediately after SG installation. This earthquake is very well recorded on SG records. The frequency and amplitude of free oscillations have been estimated and compared with earlier global observations of seismometer and SG. Estimated free oscillations validate the quality of recorded data. Precise observations of low frequency earth's free oscillations are very useful for study of source mechanism and density structure. Splitting and coupling of the free oscillations gives very useful information on the Q structure and the heterogeneity inside the earth, especially useful to constrain the long-wave length structure.

Seismic Risk in Hilly Regions D.S. Narsimha, Yogendra Singh and M.L Sharma Department of Earthquake Engineering, IIT Roorkee Email: [email protected] Abstract Earthquake is one of the disastrous catastrophes, which has occurred at many places in the world with varying magnitude and intensity at various regions causing heavy loss to life and property from the time immemorial. However, the attention to this has started only recently to concentrate on occurrence of earthquakes and to protect life and property through proper means of technical know-how. These regions include plane areas, hilly regions and trough regions individually or in combinations with varying geological features. Depending upon various geological conditions, location and type of construction, each and every earthquake has taught a lesson to professionals to think about reducing losses due the occurrence of earthquakes in future. Based on the experience of past earthquakes, professionals are now focusing on seismic vulnerability, hazard and risk. Earthquakes have particularly devastating impact in hilly areas and seismic risk assessment for hilly areas poses several challenges. The reasons for this are: (i) The topography of hilly areas modifies the earthquake motion significantly depending on the variations in the cross-section of the hill, it has been observed by various authors that responses at different locations are different for the same earthquake - hill tops are susceptible to more vibration than the its base, (ii) Hill slopes are susceptible to failure under ground shaking, resulting in landslides and devastation of habitation, (iii) The geographical conditions in hilly areas force the builders and owners to adopt irregular forms of construction. Set-back and set-off type of constructions and uneven level of foundations are common. The problem is further compounded by poor quality of construction due to non-availability of skilled manpower, poverty and lack of awareness. Some traditional knowledge of house building was existing in hilly areas to protect the construction against earthquakes. However, due to rampant use of modern material without adequate knowledge and skill, the traditional expertise has been destroyed. Hence, it is necessary that more attention be given to habitations on hilly areas particularly those on the slopes and top of hills. This paper identifies the various issues in the seismic risk assessment of Himalayan cities and expected seismic performance of the building and suggests safety measures, specific to hilly construction.

Seismic Vulnerability Assessment of Mussoorie and Josimath, Uttarakhand (India) Girish Chandra Joshi, Piyoosh Rautela and Bhupendra Bhaisora Disaster Mitigation and Management Centre, Department of Disaster Management, Government of Uttarakhand, Uttarakhand Secretariat, Dehradun - 248 001. India Abstract Himalaya has evolved due to the convergence and eventual collision of Indian and Eurasian plates and ongoing tectonism is responsible for high seismic vulnerability of the region. In the past the region has been jolted by four Great Earthquakes (magnitude > 8 on the Richter scale); 1897 Shillong Earthquake, 1905 Kangara Earthquake, 1934 Bihar-Nepal Earthquake and 1950 Assam Earthquake, apart from Kumaun earthquake of 1720 and Garhwal earthquake of 18031. Regions between the rupture zones of the great earthquakes are recognized as seismic gaps that are interpreted to have accumulated potential slip for generating future Great Earthquakes. Uttarakhand is located in the seismic gap of the 1934 Bihar-Nepal earthquake and 1905 Kangara earthquake, and is categorized under zones IV and V of the Earthquake Risk Map of India2. This region has been identified as a potential site for a future catastrophic earthquake34 and has witnessed seismic events of lesser magnitude (1991 Uttarkashi earthquake, 1999 Chamoii earthquake) in the recent past. These earthquakes have demonstrated the seismic vulnerability of the building stock in the region that was primarily responsible for large number of human casualties in these events. Most structures in the region are non-engineered and lack of awareness and knowledge amongst the masses and masons regarding earthquake resisting construction techniques results is high seismic vulnerability. Inadequate building bye laws and lenient regulatory regime only adds to the problem. Unsafe construction practices going on unabated and unless stern action is initiated soon the seismic risk is expected to rise in years to come. In order to have stock of seismic vulnerability of the built up environment in the State detailed assessment was carried out in Mussoorie and Joshimath towns of Dehradun and Chamoii districts that fall in Zone IV and V of Seismic Risk Map of India2 respectively. Every individual building of these towns was assessed for its seismic vulnerability. Data collection form of FEMA for Rapid Visual Screening (RVS)3'6 was modified to suit local conditions and was utilized for this purpose, The building stock surveyed was subsequently categorized on

Seismic Hazard Assessment Based on Attenuation Relationship for Tamil Nadu State, India S. Rajarathnam, G.P. Ganapathy and R. Muthukumar Centre for Disaster Mitigation and Management, Anna University, Chennai, Tamil Nadu, India E-mail: [email protected],co.in

Seismic Hazard Assessment is the basic approach to understand the seismic risk of population, buildings and infrastructures for an earthquake prone state or major city. It can be performed both deterministically (specific earthquake scenarios) and probabilistically (all earthquakes with their specified probabilities of occurrence). The economic and social effects of earthquakes can be reduced through a comprehensive assessment of the seismic hazard risk for seismic prone areas. The present study has been conducted using the probabilistic approach as detailed in this paper. Three principal tasks of this study (i) Defining potential earthquake sources/zones, (ii) Assigning seismicity were (maximum magnitude) to each potential source, (iii) Calculating the potential ground motions in terms of peak ground acceleration (PGA) from earthquake attenuation (loss of amplitude with distance) for all identified sources. Tamil Nadu is located in the southern most part of the Peninsular India The part of northern and western Tamil Nadu state and its capital city Chennai (formerly known as Madras) have been categorized under Zone III. The potential seismic source zones for Tamil Nadu were identified as 12 in number and they were considered for the estimation of seismic hazard assessment of Tamil Nadu State in terms of Maximum magnitude (Mmax) and Peak ground Acceleration (PGA) of the respective sources. Seven sources generated Mmax in the range of 5 to 6 (zones 1 to 7) and other five sources Mma 4.1 to 4.5. The estimated PGA for the 12 sources are in the range of 0.257g to 0. 146g. The PGA values correctable to the concept that source have higher magnitude and higher PGA. The PGA values are estimated from the closest potential source zones for major cities of Tamil Nadu viz., Chennai, Coimbatore, Salem, Madurai and Trichirappalli cities, which have PGA of 0.192 to 0.21g, 0.194g, 0.16g, 0.072g and 0.098g respectively.

Importance of seismic microzonation in urban safety ­ a case study Aftab Alam Khan SAARC Disaster Management Centre, New Delhi, India (On deputation from the University of Dhaka, Dhaka, Bangladesh) Email: [email protected]

Abstract Any physical phenomenon associated with an earthquake that may produce adverse effects on human activities is termed as earthquake hazard. This includes surface faulting, ground shaking, attenuation, amplification, liquefaction and their effects on land use, fabricated structures and socio-economic systems. Site characterization by assessing the geological state of art of a given area through earthquake-hazard microzoning should be the most prioritized task in any urban planning. Identification of active faults or the relation to any active fault source, quantification of fault activities, quantification of the ground motion, and determination of seismogenic site response are the essential components in a microzonation task. A case study was undertaken for microzonation of Dhaka University Campus, Bangladesh that covers an area 2 km by 2 km. As a take-off programme, all the existing buildings and structures were first identified, geo-referenced and classified according to its types. All the existing available bore-hole data were used to superimpose on to the geophysical imaging for subsurface characterization pertaining to natural depressions, filled zones, liquefiable zones, incised channels. Shear wave velocity profiling and microtremor survey were conducted for determining ambient g-value (acceleration due to gravity), dominant period and amplification factor. A composite site specific microzoning map is proposed for Dhaka University Campus for all future safe construction planning and strengthening of existing vulnerable buildings and structures.

Seismic hazard Microzonation of Guwahati city T. Rahman Department of Civil Engineering National Institute of Technology Silchar, Assam Email: [email protected] Abstract Guwahati is the highest populated city in the North Eastern Himalayan region has been under serious seismic threat. This city is located in seismic zone V which is considered as most severe seismic zone as per present Indian Standard code of practice IS: 1893. There are 59 active seismic source potentials around the city, which have the potential to induce severe ground vibration during earthquake. In the present paper, Guwahati city area 20 km X 18 km is divided into small grids of size 0.2 km X 0.2 km and seismic hazard at all these grids has been calculated considering all the seismic source potentials using probabilistic seismic hazard approach. In calculating the local site effects and to know the engineering properties of soil, soil samples from different 650 borehole locations of Guwahati city have been collected. Surface level seismic hazard of Guwahati city has been calculated accounting for local site effect. These surface level seismic hazards can be used conveniently as design basis ground motion parameters for designing of engineering structures in the city. These results have practical importance in engineering application for the designing of various important structures. The estimated seismic hazard value for Guwahati city includes both the Peak Ground Acceleration (PGA) and Uniform Hazard Response Spectra (UHRS). The spectra obtained in the present study using the probabilistic seismic hazard approach for Guwahati city at different location adds value to the spectra recommended by Indian Standard Code of Practice IS: 1893:2002.

Microzonation and Disaster Risk Mitigation Studies of Istanbul Metropolitan Municipality Mahmut BAS, Hikmet KARAOGLU, Ahmet Emre BASMACI Istanbul Metropolitan Municipality, Directorate of Earthquake and Ground Analysis, Sarachane, Istanbul TURKEY email: [email protected] tr Istanbul Metropolitan Municipality Directorate of Earthquake and Ground Analysis carries out assessment of possible risks and development of prevention strategies before an earthquake that may occur in Istanbul where it is regarded to be the financial, commercial, educational and industrial center of Turkey. Earthquake risk analysis, Earthquake Master Plan and microzonation studies are conducted to make Istanbul an earthquake safe city. Furthermore, risk of all building inventory and infrastructures are being determined and rehabilitated within the boundary of our authorization framework. Social and economical studies have been performed to prepare our ci ty against earthquakes. It is an underlined fact in Istanbul Earthquake Master Flan that occurrence of earthquakes can not be prevented but damages and losses can be mitigated by the application of' planning and engineering tools. Microzonation is one of the best sound practise specifically serves for urban transformation and infrastructure projects that arc put into practise step by step within the districts where earthquake and building risks are high as an outcome of Earthquake Master Plan. Microzonation work follows prioritization of areas in terms of high population density and buildings with risky local soil conditions. The aim of microzonation is to produce a 1/2000 scale earthquake hazard map that is related to land suitability concept which consumes a basis for the reconstruction plans. Microzonation is an engineering approach with a strong scientific basis in determination of areas with different potential of hazard and it provides planning, suggestions to urban transformation and development. Project within an area of 182 km2 is completed at the southern part of the European side of Istanbul and going on at the Asian side of Istanbul with an area of 458 km2. The project at the Southwestern section of Istanbul with an area of 700 km2 will be initiated. Project area is divided into 250m cells. Ground shaking, liquefaction, consolidation, landslide, flooding, surface faulting hazards are classified and mapped for each cell. After the analysis of geological, geotechnical and geophysical measurements and evaluation: Earthquake Hazard, Tsunami Hazard, Slope. Engineering Geology, Ground Water Level, fundamental Period, faulting. Ground shaking, Inundation, Shear Wave Velocity and Site Classification Maps are obtained. "Land Suitability Map" is derived from the combination of inputs using multi-hazard approach. Microzonation is an urban planning tool, which consists of multi-hazard risk analysis findings from many engineering disciplines. Results are analysed with a holistic approach. Methodology is used in planning of the location of residential housing areas, risk identification in urban transformation, routes of tunnels and bridges, pheasibility of viaducts and engineering structures.

Evaluation of Liquefaction Potential of Chandigarh City R. Dharmaraju1, S. Karthikeyan2, VVGST Ramakrishna3, C. Ghosh4 Centre for Disaster Management Administrative Training Institute, Mysore ­ 570017 (India) (Scientist on deputation from Central Building Research Institute, Roorkee) e-mail: [email protected]

2 1

Geotechnical Engineering Division Central Building Research Institute Roorkee ­ 247 667(India)

3

Osami Engineering Office Dammam, (Saudi Arabia)

4

NIDM, Govt. of India New Delhi ­ 110002 (India) ABSTRACT Chandigarh is the capital city of Punjab and Haryana with 1 million population and it is under threat from earthquakes being originated in the Himalaya. The Himalayan earthquakes have their epicenters very close to any of the terrain bounding thrusts i.e. Main Central Thrust (MCT), Main Boundary Thrust (MBT) or Himalayan Frontal Thrust (HFT). As the city has been undergoing a great thrust of developmental activity in the recent times, the seismic safety associated with booming infrastructures with little or unchecked earthquake resistant measures are at stake. Liquefaction is a earthquake induced phenomenon by which loosely packed sand deposits below the water table temporarily lose its strength and behave as a viscous liquid rather than a solid. The liquefaction hazard assessment and mapping of major cities is not very much common in India unlike the other countries. The IS: 1893­2002 also does not give any guidelines for determining liquefaction potential of a site. The paper describes the evaluation of liquefaction potential of Chandigarh city using local geology, seismotectonics and geotechnical characteristics. For this purpose, about 200+ geotechnical boreholes data have been studied along with the sub-surface geological features from the existing records. The liquefaction potential is evaluated from the results of field tests such as Standard Penetration Test (SPT) substantiated by laboratory tests on soil samples collected from the test sites. The factor of safety against liquefaction has been evaluated using Youd et al (2001) by incorporating the modifications to simplified procedure of Seed et al (1971). Based on the analysis, the factor of safety contours have been prepared with respect to different Peak Ground Acceleration (PGA). Finally, an attempt has been made to generate the seismic microzonation map of Chandigarh using liquefaction potential for a typical peak ground acceleration of 0.08g. The liquefaction susceptibility map presented in the study indicates that a major portion of city shows a mixed trend of moderate to nil safety against liquefaction. However, few sectors in the Chandigarh city are highly vulnerable to liquefaction, where the soil conditions are of non-plastic silts and fine sands having low SPT `N' values with shallow water table conditions.

Application of SHAKE for 1-D Soil Response Analysis in one borehole location at Shalimar Bagh, in NCT Delhi H.S. Mandal and A.P. Pandey Earthquake Risk Evaluation Center, IMD, New Delhi ABSTRACT An attempt has been made to compute the response spectra by using SHAKE software at one of the borehole location at Shalimar Bagh, NCT, Delhi. The most important input parameter in this program is required acceleration time history at the borehole base level generally called engineering bed rock at 30m depth. As the observed acceleration time history in the engineering bedrock depth are not available in the capital region, so it is very difficult to estimate precisely the soil responses at the surface level. However, many researcher estimated by deterministic approach the probable magnitude 6.0<M<6.7 may occur at the source if the whole fault takes rupture at a time. The well known active faults which are very near to Delhi are Shona Fault, Mathura ­Moradabad fault and Bulendar Sahar-Dehradun-Haridwar fault which are exist about 60-100km shortest distance from the heart of the capital region. The study of seism tectonics and the active fault model it is expected that about 6.5mb maximum magnitude earthquake may occur in near future. The generated strong ground motion by this magnitude earthquake may have huge potential to destruct the environmental design structure of the city which is about 60100km a-part form the source. It is also well known that the existing buildings in the capital region are not designed according to the latest building code on the basis of the seismic designed parameters. Keeping in view and available data of bore logs such as water-table, blow counts (SPT, N-values), unit weight density and some advance laboratory test data we used in SHAKE program to compute the 1-dimensional (1-D) soil response analysis at ground surface with respect to bottom of the well. As the expected strong ground motion at the base level of the borehole is not available in our territory so, authors used here the KiK-Net strong ground motion data of Japan with equivalent earthquake of magnitude 6.5mb. Many boreholes have been constructed during 1997 and there after by Delhi Development Authority (DDA) for soil investigation for soil investigation designed purposes in the different area in Capital city Delhi. One of borehole is used here for demonstration and practices to see the non-linear behavior of the soil at pocket-A, block-D, Shalimarbagh. The borehole (BH-01) drilled up to 25m below the ground and its laboratory soil analysis is available in their report. We have been divided the entire vertical soil column into seven material properties and 19 sub-layers upto the bottom of the well. The layers are counted beginning from ground surface and end with base level of the borehole. The shear wave velocities for different layers are calculated from the standard relation ship between numbers of blow counts (N-value) with shear wave velocities. The shear wave velocities are varies at the top 170m/s to 370m/s. The hyperbolic model with parameters the internal frictional angle ( ), cohesions (C) and 2% minimum damping are used in the program. The amplification factor at surface to bedrock is 4.3 corresponding peak frequencies 1.85Hz. The peak amplification factor estimated in this study is compared with result obtained through Nakamura Techniques (H/V). The peak ground acceleration (PGA) 0.3g is also estimated by this method at the surface level, which is well with in the range of PGA derived through Probabilistic Seismic Hazard Analysis(PSHA) elsewhere. The response spectra for damping 2%, 5%, 10% and15% are also calculated for earthquake resistance designed structures.

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