Seismic hazard in mega city Kolkata, India

The damages caused by recent earthquakes in India have been a wake up call for people to take proper mitigation measures, especially the major cities that lie in the high seismic hazard zones. Kolkata City, with thick sediment deposit (∼12 km), one of the earliest cities of India, is an area of great concern as it lies over the Bengal Basin and lies at the boundary of the seismic zones III and IV of the zonation map of India. Kolkata has been affected by the 1897 Shillong earthquake, the 1906 Calcutta earthquake, and the 1964 Calcutta earthquake. An analysis on the maximum magnitude and b-value for Kolkata City region is carried out after the preparation of earthquake catalog from various sources. Based on the tectonic set-up and seismicity of the region, five seismic zones are delineated, which can pose a threat to Kolkata in the event of an earthquake. They are broadly classified as Zone 1: Arakan-Yoma Zone (AYZ), Zone 2: Himalayan Zone (HZ), Zone 3: Shillong Plateau Zone (SPZ), Zone 4: Bay of Bengal Zone (BBZ), and Zone 5: Shield Zone (SZ). The maximum magnitude (mmax) for Zones 1, 2, 3, 4, and 5 are 8.30 ± 0.51, 9.09 ± 0.58, 9.20 ± 0.51, 6.62 ± 0.43 and 6.61 ± 0.43, respectively. A probability of 10% exceedance value in 50 years is used for each zone. The probabilities of occurrences of earthquakes of different magnitudes for return periods of 50 and 100 years are computed for the five seismic zones. The Peak Ground Acceleration (PGA) obtained for Kolkata City varies from 0.34 to 0.10 g.

[1]  Göran Ekström,et al.  Global seismicity of 2003: centroid–moment-tensor solutions for 1087 earthquakes , 2005 .

[2]  D. Giardini,et al.  The Global Seismic Hazard Assessment Program (GSHAP) , 1992 .

[3]  F. Vaccari,et al.  Site-specific Microzonation Study in Delhi Metropolitan City by 2-D Modelling of SH and P-SV Waves , 2004 .

[4]  William K. Mohanty,et al.  First Order Seismic Microzonation of Delhi, India Using Geographic Information System (GIS) , 2007 .

[5]  P. Molnar,et al.  Source parameters of earthquakes and intraplate deformation beneath the Shillong Plateau and the northern Indoburman ranges , 1990 .

[6]  T. Topal,et al.  Microzonation for earthquake hazards: Yenisehir settlement, Bursa, Turkey , 2003 .

[7]  A. Gupta,et al.  Geology of Assam , 2000 .

[8]  Domenico Giardini,et al.  The Global Seismic Hazard Assessment Program (GSHAP) , 1993 .

[9]  G. R. Toro,et al.  Model of Strong Ground Motions from Earthquakes in Central and Eastern North America: Best Estimates and Uncertainties , 1997 .

[10]  A. Kijko,et al.  Estimation of earthquake hazard parameters from incomplete data files. Part I. Utilization of extreme and complete catalogs with different threshold magnitudes , 1989 .

[11]  G. Atkinson,et al.  Ground-motion relations for eastern North America , 1995, Bulletin of the Seismological Society of America.

[12]  Andrzej Kijko,et al.  Estimation of the Maximum Earthquake Magnitude, mmax , 2004 .

[13]  Probabilistic Seismic Hazard Assessment for Iraq Using Complete Earthquake Catalogue Files , 2005 .

[14]  F. Vaccari,et al.  Deterministic Earthquake Scenarios for the City of Sofia , 2004 .

[15]  K. Campbell,et al.  Updated Near-Source Ground-Motion (Attenuation) Relations for the Horizontal and Vertical Components of Peak Ground Acceleration and Acceleration Response Spectra , 2003 .

[16]  U. Chandra.  Seismotectonics of Himalaya , 1992 .

[17]  A. El-Sayed,et al.  Seismicity and Seismic Hazard in Alexandria (Egypt) and its Surroundings , 2004 .

[18]  R. Oldham,et al.  Report on the great earthquake of 12th June 1897 , 1899 .

[19]  F. Vaccari,et al.  Linear Amplification of Horizontal Strong Ground Motion in Zagreb (Croatia) for a Realistic Range of Scaled Point Sources , 2004 .

[20]  Harsh K. Gupta,et al.  A probabilistic seismic hazard map of India and adjoining regions , 1999 .

[21]  V. Gupta,et al.  A Probabilistic Seismic Hazard Analysis of Northeast India , 2006 .

[22]  W. B. Joyner,et al.  Equations for Estimating Horizontal Response Spectra and Peak Acceleration from Western North American Earthquakes: A Summary of Recent Work , 1997 .

[23]  S. Kramer.  Geotechnical Earthquake Engineering , 1996 .

[24]  John H. Woodhouse,et al.  Determination of earthquake source parameters from waveform data for studies of global and regional seismicity , 1981 .

[25]  Andrzej Kijko,et al.  Estimation of earthquake hazard parameters from incomplete data files. Part II. Incorporation of magnitude heterogeneity , 1992 .

[26]  D. Shanker,et al.  Estimation of Seismic Hazard Parameters for the Himalayas and its Vicinity from Complete Data Files , 1998 .

[27]  C. Davison.  III.—Report on the Great Earthquake of June 12th, 1897 . By R. D. Oldham, A.R.S.M., F.G.S., Superintendent, Geological Survey of India. Mem. Geol. Survey of India, vol. xxix. (Calcutta, 1899.) , 1900, Geological Magazine.

[28]  Mehmet Celebi,et al.  Engineering Aspects of the September 19, 1985 Mexico Earthquake , 1987 .

[29]  G. Panza,et al.  Estimation of Site Effects in Beijing City , 2004 .

[31]  Giuliano F. Panza,et al.  Microzonation of Bucharest: State-of-the-Art , 2004 .

[32]  Codal provisions of seismic hazard in Northeast India , 2005 .

[33]  Sankar Kumar Nath,et al.  Seismic Hazard Mapping and Microzonation in the Sikkim Himalaya through GIS Integration of Site Effects and Strong Ground Motion Attributes , 2004 .

[34]  Gail M. Atkinson,et al.  Some Comparisons Between Recent Ground- Motion Relations , 1997 .