First Order Seismic Microzonation of Haldia, Bengal Basin (India) Using a GIS Platform |
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| Authors: | William K Mohanty M Yanger Walling |
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| Institution: | (1) Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur, 721 302, West Bengal, India |
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| Abstract: | The seismic microzonation of the Bengal Basin, Haldia region, India is carried out using the Analytical Hierarchy Process
(AHP) on the Geographic Information System (GIS). Three themes are used for the seismic microzonation, namely Peak Ground
Acceleration (PGA), predominant frequency and elevation map. An analysis of the maximum magnitude (m
max) and the b value is carried out after preparing the earthquake catalogue from various sources. On the basis of the tectonic
set up and seismicity of the region, five seismic zones are delineated which can be a threat to Haldia. 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 m
max 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. The PGA
value is computed for Haldia following the attenuation relationship taking the m
max of each source zone. The expected PGA at Haldia varies from 0.09–0.19 g. The predominant frequency of Haldia is also calculated
using the H/V ratio with a frequency ranging from 0.1–3.0 Hz. The elevation map of Haldia is also generated using the Shuttle
Radar Topography Mission (STRM) data. A first-order seismic microzonation map of Haldia is prepared in which four zones of
hazard have been broadly classified for Haldia as very high seismic hazard zone, high seismic hazard zone, moderate seismic
hazard zone and less seismic hazard zone. The very high seismic hazard zone is observed along the southern part of Haldia
where there are major industrial and port facilities. The PGA for the four hazard zones are: 0.09–0.13 g for low hazard zone,
> 0.13–0.15 g for moderate hazard zone, > 0.15–0.16 g for high hazard zone and > 0.16–0.19 g for very high hazard zone. |
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| Keywords: | :" target="_blank">: Seismic microzonation seismic hazard PGA predominant frequency GIS |
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