Papers by Ganapathy Pattukandan Ganapathy
Seismic risk in urban areas is the greatest and most rapidly growing hazard in developing countri... more Seismic risk in urban areas is the greatest and most rapidly growing hazard in developing countries. The highest seismic risk in India is concentrated in the north and northeast parts, which is home to approximately 60 percent of the population of the country. The Chennai city is one of the well urbanized and densely populated urban centre in where the majority of buildings are reinforced concrete structures containing three to four stories. The city has an area of 170 sq.km and the total population of city is 43.43 lakhs as on 2001 Census. Major part of the city is covered by Recent alluvium to the thickness maximum of 28m and these deposits can amplify in multifold generally 3.9. Bureau of Indian Standard (BIS 1893(Part 1)-2002) categorized the city under Seismic zone III (prone to moderate seismic hazard-we can expect earthquake magnitude upto 6.9 in this zone). Such being the case, safety of this city is extremely important to safeguard the human lives and infrastructures. The present paper aims to bring out seismic hazard map for Chennai city using the geotechnical parameters. The potential seismic sources for this region have been delineated based on the seismoteconic parameters for the Chennai and its vicinity. The expected ground motion in terms of Peak Ground Acceleration calculated based on attenuation relationship. The seismic hazard potential for the city estimated using the geotechnical parameters viz, SPT 'N' values, shear wave velocity, relative amplification factor and intensity increment and presented in the form of maps. The present map will be helpful in cases where the seismic hazard is assessed to be high; more detailed geophysical investigations may be required for site specific micro seismic zonation maps for further land use planning purposes.
Chennai, the capital City of Tamil Nadu covers an area of 170.98 Sq,km is the fourth largest Metr... more Chennai, the capital City of Tamil Nadu covers an area of 170.98 Sq,km is the fourth largest Metropolitan City in India and is experiencing rapid growth in population. An understanding of Seismic Hazard is necessary for Chennai city where even moderate earthquakes have high hazard potential in larger areas due to the dense population and efficient transmission of wave energy. A study on Seismic Hazard Analysis for Chennai city carried out based on deterministic approach using remote sensing and GIS techniques. The seismic potential sources have been identified based on satellite remote sensing data integrated with past earthquake epicenters and limited field checks. Shortest distance from the each seismic source to the Chennai City measured by Arc-Info Measuring tool and the Peak Ground Acceleration (PGA) at bed rock level is calculated for the identified sources with their maximum credible earthquake events using available attenuation relationship formula applicable to Peninsular India. To calculate hazard in the area, a grid is formed dividing each degree of latitude and longitude in to three parts. Arc-GIS layout tool is used to perform the grid analysis. The seismic hazard of Chennai city is expressed in the form of iso-acceleration contours. The estimated maximum PGA from the four seismic source zones was in the range of 0.145g to 0.078g. The contour of PGA values generated by the different sources indicates the seismic source in the eastern part of the study area is to be have more attention for further research.
Natural disasters itself are inevitable and have a drastic effect on our lives and have proven to... more Natural disasters itself are inevitable and have a drastic effect on our lives and have proven to be detrimental to our economy as well. The risk of human life due to natural disasters can be avoided by looking back into our past. The method of assessing the impact of past occurrences of hazards will provide us with enough information to react effectively and be prepared for all eventualities. The past experience has shown that the occurrence of small and medium scale disasters can be a precursor to big disasters, and the cumulative impact of small and medium disasters may equal or even exceed that of big disasters.
Chennai city with population of 6 million experienced three earthquakes of M ≥ 5.0 in the years 1... more Chennai city with population of 6 million experienced three earthquakes of M ≥ 5.0 in the years 1807, 1816 and 1823. Chennai city falls under Seismic Zone III and such being the case, Chennai is liable for site-specific amplification of seismic motion. The objectives of this paper to bring out the seismic hazard map of Chennai in terms of intensity increment for a known earthquake magnitude. The Seismic Hazard of Chennai city evaluated based upon local ground motion response or local site effects with the geotechnical data from 450 boreholes by correlation, integration and interpretation of parameters viz., SPT-N values, average shear wave velocity, relative amplification factors and intensity of increment of earthquake. The combined seismic hazard prone areas at different depths for Chennai represent the percentage of medium, high and very high hazard is 31.3%, 39.2% and 2.7% respectively. In the present study the data gap is 26.8%.
Seismic risk in urban areas is the greatest and most rapidly growing hazard in developing countri... more Seismic risk in urban areas is the greatest and most rapidly growing hazard in developing countries. The highest seismic risk in India is concentrated in the north and northeast parts, which is home to approximately 60 percent of the population of the country. The Chennai city is one of the well urbanized and densely populated urban centre in where the majority of buildings are reinforced concrete structures containing three to four stories. The city has an area of 170 sq.km and the total population of city is 43.43 lakhs as on 2001 Census. Major part of the city is covered by Recent alluvium to the thickness maximum of 28m and these deposits can amplify in multifold generally 3.9. Bureau of Indian Standard (BIS 1893(Part 1) -2002) categorized the city under Seismic zone III (prone to moderate seismic hazard -we can expect earthquake magnitude upto 6.9 in this zone). Such being the case, safety of this city is extremely important to safeguard the human lives and infrastructures. The present paper aims to bring out seismic hazard map for Chennai city using the geotechnical parameters. The potential seismic sources for this region have been delineated based on the seismoteconic parameters for the Chennai and its vicinity. The expected ground motion in terms of Peak Ground Acceleration calculated based on attenuation relationship. The seismic hazard potential for the city estimated using the geotechnical parameters viz, SPT 'N' values, shear wave velocity, relative amplification factor and intensity increment and presented in the form of maps. The present map will be helpful in cases where the seismic hazard is assessed to be high; more detailed geophysical investigations may be required for site specific micro seismic zonation maps for further land use planning purposes.
Landslide is one of the major natural hazards that are commonly experienced in hilly terrains all... more Landslide is one of the major natural hazards that are commonly experienced in hilly terrains all over the world. Landslides are affect at least 15 per cent of the land area of India-an area which exceeds 0.49 million km2. In India the incidence of landslides in Himalayas and other hill ranges is an annual and recurring phenomenon.
Tamil Nadu State, with an area of 130, 058sq.km located in the southern most part of the Peninsul... more Tamil Nadu State, with an area of 130, 058sq.km located in the southern most part of the Peninsular India is selected for the present study on seismic hazard assessment. The part of northern and western Tamil Nadu State including its capital city Chennai have been categorized under Moderate Seismic Hazard (Zone III) areas, by Bureau of Indian Standard (BIS) in 2001. A catalog of historical/instrumental earthquakes/ earth tremors in the state has been prepared and used in this paper. The earthquakes having magnitude of greater than 3.0 have been considered for the present study. The seismic sources have been identified using remote sensing images with limited ground truth verification. Seven near potential seismic sources in the region delineated as area sources for seismic hazard assessment based on geological, seismological and geophysical information. Shortest distance from the each seismic source to the major cities of Tamil Nadu measured and the Peak Ground Acceleration (PGA) at bed rock level is calculated for the seven sources with their maximum credible earthquake events using available attenuation relationship formula. The maximum magnitude associated with these potential seismic sources is in the range of 6.0 to 5.0 in Richter scale and the estimated on Peak Ground Acceleration at the source is 0.212 to 0.078g. The PGA values are estimated from the closest potential source for major cities of Tamil Nadu viz., Chennai, Coimbatore, Salem, Madurai and Trichirappalli cities, which have PGA of 0.107g, 0.133g, 0.012g, 0.077g & 0.113g respectively. The result of the present study reveals that the seismic hazard in northeastern and western part of the state is closely matching with the Seismic Zonation map published by the BIS. However the east southeastern part of the state shows higher value because of the adequate earthquake data used
Chennai city is the fourth largest metropolis in India, is the focus of economic, social and cult... more Chennai city is the fourth largest metropolis in India, is the focus of economic, social and cultural development and it is the capital of the State of Tamil Nadu. The city has a multi-dimensional growth in development of its infrastructures and population. The area of Chennai has experienced moderate earthquakes in the historical past. Also the Bureau of Indian Standard upgraded the seismic status of Chennai from Low Seismic Hazard (Zone II) to Moderate Seismic Hazard (Zone III)-(BIS: 1893 ). In this connection, a first level seismic microzonation map of Chennai city has been produced with a GIS platform using the themes, viz, Peak Ground Acceleration (PGA), Shear wave velocity at 3 m, Geology, Ground water fluctuation and bed rock depth. The near potential seismic sources were identified from the remote-sensing study and seismo-tectonic details from published literatures. The peak ground acceleration for these seismic sources were estimated based on the attenuation relationship and the maximum PGA for Chennai is 0.176 g. The groundwater fluctuation of the city varies from 0-4 m below ground level. The depth to bedrock configuration shows trough and ridges in the bedrock topography all over the city. The seismic microzonation analysis involved grid datasets (the discrete datasets from different themes were converted to grids) to compute the final seismic hazard grid through integration and weightage analysis of the source themes. The Chennai city has been classified into three broad zones, viz, High, Moderate and Low Seismic Hazard. The High seismic Hazard concentrated in a few places in the western central part of the city. The moderate hazard areas are oriented in NW-SE direction in the Western part. The southern and eastern part will have low seismic hazard. The result of the study may be used as first-hand Correspondence to: G. P. Ganapathy ([email protected]) information in selecting the appropriate earthquake resistant features in designing the forthcoming new buildings against seismic ground motion of the city. 1
Even small number of built-up areas experienced landslide problems; however, the loss could rise ... more Even small number of built-up areas experienced landslide problems; however, the loss could rise when the built-up areas develop in and on the unstable slopes. Landslide hazard information serves one of the many components in an integrated development planning study. A study on spatial vulnerability assessment is carried out for the part of Nilgiris district in the Western Ghats of India with the help of remote sensing and geographical information system to make use of landslide planning scenario. A spatial database is created for past landslide histories in the study area. The critical facilities, transportation and lifeline utilities, which include tourist spots, banks, ATMs, educational institutions, hospitals, bus stops, railway stations, that are potential threat under the very high to severe landslide hazard areas were identified. These are the elements at risk during landslides. From the study, it has been found that the eastern part of the study area is more prone to landslides. The past landslide inventories very clearly reveal that most of the landslides are triggered by the intense rainfall, human and cultural activities. Out of 36 utilities in the study area, about 65 % critical facilities and 36 % of transportation and lifeline utilities are vulnerable to severe landslide threat. The output of the present study can be used as first-hand information for the decision makers and planners and also helpful for the further developmental activities in the landslide-prone areas of the Nilgiris district of India.
According to the latest UNFA Report on state of world population 2007, unleashing the potential o... more According to the latest UNFA Report on state of world population 2007, unleashing the potential of urban growth by 2030, the urban population will rise to 5 billion or 60 % of the world population. Liquefaction in urban areas is dangerous phenomenon, which cause more damage to buildings and loss of human lives. Chennai, the capital city of the State Tamil Nadu in India, is one of the densely populated cities in the country. The city has experienced moderate magnitude earthquakes in the past and also categorized under moderate seismic hazard as per the Bureau of Indian Standards (BIS in Criteria for earthquake resistant design of structures; Bureau of Indian Standards, New Delhi, 1893 2001). A study has been carried out to evaluate the liquefaction potential of Chennai city using geological and geomorphological characteristics. The subsurface lithology and geomorphological maps were combined in the GIS platform for assessing the liquefaction potential. The liquefaction hazard broadly classified into three categories viz., liquefaction likely, possible and not likely areas. Mainly, the liquefaction likely areas spread along the coastal areas and around the river beds. The rest of the areas are liquefaction not likely and possible. The present map can be used as first-hand information on regional liquefaction potential for the city, and it will be help to the scientists, engineers and planners who are working for future site-specific studies of the city.
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Papers by Ganapathy Pattukandan Ganapathy