Predicting Seismic Vulnerable Zones using GIS. Outline of the presentation. Objectives. Risk Mapping Overview Factor Maps. Three levels of Zonation

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1 Predicting Seismic Vulnerable Zones using GIS by K.S.A. Dinesh Kumar Research Scholar, Anna University & Lecturer in Civil Engineering Dept. National Institute of Technical Teachers Training & Research (NITTTR), Chennai Dr. E.S.M. Suresh Asst. Professor of EMC NITTTR, Chennai. Dr. S.S. Ramakrishnan Professor, Institute of Remote Sensing Anna University, Chennai. Outline of the presentation Introduction Objectives Methodology Maps Conclusion 1 2 Introduction Rapid Urbanization & Rapid spread of modern life style, it appears that Earthquake disaster is becoming more complicated. In recent decades earthquakes with magnitude of 5 & 6 has occurred in southern India which forced to study of peninsular seismic vulnerable zones in detail. Chennai urban is growing very rapidly. The most buildings are not meeting codal requirements on seismic resistance. Necessary to analyse the earthquake vulnerable zones at Chennai city. Objectives To identify vulnerable zone of Chennai city To analyse various parameters for stability of structures against Earthquake To develop micro level planning for earthquake To develop Vulnerability Sensitivity Index To prepare guide line document for new proposed structures & existing structures against stability GIS is a powerful tool for the assessment of risk and management of Natural Hazards 3 4 Risk Mapping Overview Factor Maps Hazard Maps Multiple Hazard Maps Vulnerability Analysis of Buildings Risk to the Buildings & and physical layout Vulnerability analysis of Infrastructure Maps other elements in the physical layout Three levels of Zonation Grade 1: General Zonation (1:50,000 to 1: 10,00,000) (Ref: Report of Technical Committee on Earthquake Geotechnical Engg., of the International Society of Soil Mechanics and Foundation Engg.) Input Existing Body of multisource Information (historic documents, published reports at other available data) Catalogues of instrumentally monitored earthquakes Human Habitat & Infrastructure at risk Existing geological & geomorphological maps Feed back from actual studies Combined Risk Base Maps Socio-economic elements at Risk 5 Site Investigation reports of major construction projects 6 Source: UNDRO Manual

2 Output The first level map Reliability Depends on the quality of the input information Grade 2: Detailed Zonation (1:10,000 to 1: 1,00,000) Input Mobilization of additional data to fill in information gaps in the general zonation (first level) exercise. This would require study of satellite imageries, air photos, and some additional ground mapping. Micro tremor studies for subsurface details and ground amplification 7 8 Grade 3: Rigorous Zonation Outputs Detailed map Reliability Reasonable (1:5,000 to 1: 25,000) Input Additional site investigation data Seismic ground response analyses Liquefaction hazard mapping Slope instability behaviour Outputs Rigorous map Present Status of Chennai City Reliability The Highest 11 Source: CDMM Seismic Microzonation,

3 Growth of Population in Chennai City, City Population in lakhs Area in Sq.km Annual Rate of growth of population *(in percent) Population density per Hect *Note: Arrived for a unit area for the purpose of comparison since the city extent varied over time. The figures given are for the decade ended with that year Year 1961 Migration to Chennai City, (in Lakhs) Populati- -on Other parts of Tamil Nadu No % migrants to the city from Other parts of India (Excluding Tamil Nadu) No % Other Countries No % Unclassifiable migrants % of Migran ts to the total populat ion Source: Census of India, 1961, & 1981, 1991 Social and Cultural Table Chennai City Average Annual Rate of Change of Population - 01 Sl. No. 1 2 Projected Population for CMA & Chennai City (in Lakhs) Description CMA Chennai City Actual Projection

4 19 20 Fig: Zone Zone V Zone IV Zone III Zone II Magnitude Very High Risk Quakes of Magnitude 8 and greater High Risk Quakes upto Magnitude 7.9 Moderate Risk Quakes upto Magnitude 6.9 Seismic Disturbances upto Magnitude 4.9 Source: IS 1893 (Part 1) : 2002 (BIS) Seismicity Of Chennai Recent tremors occurred in Chennai 26 th Dec, 2004 Sumatra earthquake 28 th Jun, 2008 Andaman Nicobar earthquake 13 th Aug, 2009 Andaman Nicobar earthquake Earthquake catalogues of NEIC, USA shows 67 earthquakes within 300 km from Chennai since 1800 A.D. onwards 450 earthquakes in Peninsular India 23 24

5 Fault map of Chennai city Faults within 100 km from Chennai were found In the zone of influence, 4 faults, 2 major lineaments and several other minor lineaments were observed Palar fault, located at a distance of 68 km from the Chennai city was identified as a future seismic source for the city Methodology Preparation of maps from remote sensing data 1 Landuse map 2 Geomorphology map 3 Geology map 4 Slope map 5 Drainage density & Soil GPS data collections Seismic Vulnerability of structures 1. Type of structure 2. Age of structure 3. Building shape 4. Number of stories 5. Space between adjacent structures Identification of vulnerable zones Vulnerability Sensitivity Index (VSI) Nondestructive Testing 27 Preparation of Guideline document 28 Geology Map MAPS 29 30

6 South and SW Igneous/metamorphic rocks East Fluvio-Marine sedments containing clay-silt sands; Charnockite rocks North, West and SW Adyar, Cooum and Kortaliyar river alluvium, sedimentary rocks South Gondwana rocks, Tertiary rocks (sandstones, shales and boulder beds) The thickness of alluvium ranges from a few meters in the south to 52 to 80 m in the north Land use Map Existing Land Use of CMA Proposed land use Map Proposed Land Use of Chennai City Soil type 35 36

7 Types of Buildings in Chennai City No. of Households and Housing Units in Chennai City and CMA (in Lakhs) Growth rate in % RCC Buildings Masonry buildings Buildings with light roofs Households in the City Households in the CMA Housing Units in the City Housing Units in the CMA Source : Census of India 38 Rate of Change in Population, Households and Housing Units, - - CMA Annual rate of growth in population Annual rate of growth in Households Annual rate of growth in Housing units Chennai City Distribution of Houses by Predominant Material of Wall, Plastic, Polythene Wood Brick Stone Concrete Others Source: Census of India Type of Wall Grass, Thatch, Bamboo wood Mud, Unburnt brick GI Metal, Asbestos sheets Number of Houses 3,33,959 1,671 29,438 1,208 9,061 6,22,304 49,363 2,08,516 1,556 % to Distribution of Houses by Predominant Nature of Roof Chennai City Sl.No Tiles Slate Brick Stone Concrete Any other Material Source: Census of India Type Grass, Thatch, Bamboo wood etc. Plastic and Polythene GI Metal, Asbestos sheets Number of Houses 90,735 2,966 71,403 1,662 65,392 18,908 5,246 6,96,997 3,767 % to Sl.No Growth of Slums in Chennai City Year No. of Slums No. of the households 57,436 97,851 1,63,802 1,27,181 1,78,000 Slum Population 2,87,180 4,12,168 7,37,531 6,50,859 8,20,000 42

8 Location of Slums in Chennai City, 2000 Sl.No. 1 Description River Margin No. of Slum Families 30,922 Sl.No. 1 Name of the River Cooum River No. of Slum Families 8,432 2 Feeder Canals 5,288 2 Buckingham Canal 15,733 3 Road Margin 22,769 3 Adyar River 6,757 4 Seashore 16,519 30,922 75, Weaknesses in Buildings Planning and architectural aspects - Irregularities in Plan or Elevation invite torsion loads. - Simple Square or Rectangular perform well Structural deficiencies - Open bottom storey for car park - Long Cantilevers - Floating columns Construction deficiencies - Quality of Construction - Poor Detailing of reinforcement 45 Non Destructive Valuation of Structures Ultra Sound Pulse Velocity Rebound Hammer These test will help to compute the available resistance of both concrete and reinforcement of the existing building Source: Sep 07, Hindu Article on Seismic Vulnerabilityof buildings in Chennai by Dr.A.R. Santhakumar, Emeritus Professor, IIT Madras 46 Conclusion The various vulnerable zones of Chennai city can be identified Various parameters for stability of structures against Earthquake can be developed Micro level planning for earthquake canl be developed THANK YOU Vulnerability Sensitivity Index can be generated for the city Guide line document for new proposed structures & existing structures against stability can be developed 47 48