First level seismic microzonation map of Chennai city – a GIS approach

Ganapathy, G.P.

doi:10.5194/nhess-11-549-2011

Cited by 36 publications

(22 citation statements)

References 13 publications

(5 reference statements)

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“…Rajarathnam (1994), Srinivasan et al (2011), Ganapathy (2011 and Maheswari et al (2008) have also carried out source characterization studies within 300 km radius from Chennai covering part of Tamil Nadu and Andhra Pradesh based on 200 years of past earthquake data. The attenuation relationship developed by Kanth and Iyengar (2007) particularly for the Peninsular India based on a statistically simulated seismological model is used by various authors who have arrived at the conclusion that the maximum PGA at rock level for Chennai city is 0.134 g (Maheswari et al 2008) and 0.176 g (Ganapathy 2011), respectively. The GSI has identified 12 major faults with magnitude range of 4-5.5 and hypocentral distances 32-280 kms.…”

Section: Seismicity Of Chennai Citymentioning

confidence: 97%

Assessment of seismic building vulnerability based on rapid visual screening technique aided by aerial photographs on a GIS platform

Rajarathnam

Santhakumar

2015

Nat Hazards

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The stability of buildings in seismic prone areas depends upon the structural behavior of buildings subjected to ground motion. Buildings of plan and vertical irregularities with respect to either geometry or stiffness have exhibited poor performance during past earthquakes. Identification of seismic building vulnerability is required for metropolitan cities which have moderate to high level of seismic proneness and have a high building density. Inspection of a large number of buildings individually requires enormous time and manpower. Using aerial photograph approach in GIS platform is an ideal choice to overcome these constraints. Chennai city is the thirty-fourth largest city in the world and prone to moderate earthquake hazards. This paper presents a methodology to analyze and predict the seismic vulnerability of buildings with five storeys and above in Chennai. Aerial photographic data of all buildings, land features and roads, within the city and its direct surroundings, were digitized and incorporated on a GIS platform, resulting in a digital vector map. A number of structural parameters determined on the basis of engineering knowledge and observations through rapid visual screening (RVS) have been used to identify the plan and vertical irregularities of the buildings. A new vulnerability scoring system to identify the level of damageability has been introduced based on RVS technique and compared with traditional grading system. Subsequent to RVS, a database of buildings having different range of vulnerability scores has been prepared. The percentage of desirable and undesirable features of buildings with respect to their contribution to damage was assessed based on past experiences and vulnerability scores of buildings. The survey shows that 30 % of the buildings are in the A category of being vulnerable to collapse. There are no buildings that can be classified as defect-free. It is also to note that 55-70 % of buildings lie in the category of D (low damage vulnerability).

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Section: Seismicity Of Chennai Citymentioning

confidence: 97%

Assessment of seismic building vulnerability based on rapid visual screening technique aided by aerial photographs on a GIS platform

Rajarathnam

Santhakumar

2015

Nat Hazards

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“…The earthquake map is based on the probabilistic seismic hazard analysis taking into account bedrock condition and active fault distribution [9]. Considering the scale of the national map, there is a necessity to provide seismic microzonation studies in determining the PGA taking into account the local site effects of geological conditions based on the actual site investigation and field measurement, especially for densely populated areas [10], [11], [12]. Previously, single observation of microtremors to estimate the site-dependent amplification characteristics and microtremor array investigation to gain the soil condition of subsurface structures have been conducted in Padang [13] and Palu [14] of Indonesia.…”

Section: Introductionmentioning

confidence: 99%

Seismic Microzonation Studies Considering Local Site Effects for Yogyakarta City, Indonesia

Fathani¹

2017

GEOMATE

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An Mw 6.3 earthquake hit Yogyakarta, Indonesia in 2006, causing massive damage in this densely populated area. As a consequence, risk reduction efforts in terms of local seismic response and peak ground acceleration (PGA) mapping is needed to improve the spatial planning and early assessment before another disastrous earthquake. The determination of PGA for microzonation study was conducted by referring to the Indonesian seismic code and empirical prediction by examining attenuation relationships considering the local site effects. The site investigation was conducted at 87 locations, comprising 13 core drillings and 74 microtremor measurements. Further, the nonlinear earthquake site response analyses were conducted to calculate the local seismic response occurring in a layered soil. Referring to the seismic code with a 2% probability of exceedance in 50 years and site characteristics, the maximum considered earthquake geometric mean PGA for Yogyakarta City is 0.50-0.57g, while the southern area has higher PGA. The empirical prediction by attenuation relationships that considers the 6.3 Mw Yogyakarta earthquake 2006 with 50-100 year return period resulted in PGA of 0.14g to 0.21g. Meanwhile, the empirical prediction based on soil predominant period resulting from microtremor measurements shows that the southern part of the city has higher PGA of 0.2g to 0.3g whereas the northern part has lower PGA of 0.1g to 0.2g. The result of nonlinear earthquake site response analyses shows that the PGA at the southern part and the northern part of the city have higher PGA up to 0.38g. The results show the significance of local site effects and site response analysis in determining the earthquake characteristics in comparison to the present simplified empirical approach.

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“…Multicriteria seismic hazard microzonation has been carried out previously in other Indian regions -Guwahati , the Sikkim Himalaya (Nath, 2004;Pal et al, 2008), Delhi (Mohanty et al, 2007), Bangalore (Anbazhagan et al, 2010) and Chennai (Ganapathy, 2011).The hazard mapping is achieved through use of a multicriteria-based decision support tool formulated by Saaty (1980) referred to as an analytical hierarchal process (AHP). AHP uses hierarchical structures to quantify relative priorities for a given set of elements on a ratio scale, which is based on the discernment of the user.…”

Section: Multicriteria Seismic Hazard Microzonation Of Kolkatamentioning

confidence: 99%

Earthquake scenario in West Bengal with emphasis on seismic hazard microzonation of the city of Kolkata, India

Nath

Adhikari

Maiti

et al. 2014

Nat. Hazards Earth Syst. Sci.

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Abstract. Seismic microzonation is a process of estimating site-specific effects due to an earthquake on urban centers for its disaster mitigation and management. The state of West Bengal, located in the western foreland of the AssamArakan Orogenic Belt, the Himalayan foothills and Surma Valley, has been struck by several devastating earthquakes in the past, indicating the need for a seismotectonic review of the province, especially in light of probable seismic threat to its capital city of Kolkata, which is a major industrial and commercial hub in the eastern and northeastern region of India. A synoptic probabilistic seismic hazard model of Kolkata is initially generated at engineering bedrock (V 30 s ∼ 760 m s −1 ) considering 33 polygonal seismogenic sources at two hypocentral depth ranges, 0-25 and 25-70 km; 158 tectonic sources; appropriate seismicity modeling; 14 ground motion prediction equations for three seismotectonic provinces, viz. the east-central Himalaya, the Bengal Basin and Northeast India selected through suitability testing; and appropriate weighting in a logic tree framework. Site classification of Kolkata performed following in-depth geophysical and geotechnical investigations places the city in D1, D2, D3 and E classes. Probabilistic seismic hazard assessment at a surface-consistent level -i.e., the local seismic hazard related to site amplification performed by propagating the bedrock ground motion with 10 % probability of exceedance in 50 years through a 1-D sediment column using an equivalent linear analysis -predicts a peak ground acceleration (PGA) range from 0.176 to 0.253 g in the city. A deterministic liquefaction scenario in terms of spatial distribution of liquefaction potential index corresponding to surface PGA distribution places 50 % of the city in the possible liquefiable zone. A multicriteria seismic hazard microzonation framework is proposed for judicious integration of multiple themes, namely PGA at the surface, liquefaction potential index, NEHRP soil site class, sediment class, geomorphology and ground water table in a fuzzy protocol in the geographical information system by adopting an analytical hierarchal process. The resulting high-resolution surface consistent hazard, liquefaction and microzonation maps are expected to play vital roles in earthquake-related disaster mitigation and management of the city of Kolkata.

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First level seismic microzonation map of Chennai city – a GIS approach

Cited by 36 publications

References 13 publications

Assessment of seismic building vulnerability based on rapid visual screening technique aided by aerial photographs on a GIS platform

Assessment of seismic building vulnerability based on rapid visual screening technique aided by aerial photographs on a GIS platform

Seismic Microzonation Studies Considering Local Site Effects for Yogyakarta City, Indonesia

Earthquake scenario in West Bengal with emphasis on seismic hazard microzonation of the city of Kolkata, India

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