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| Titel |
Earthquake scenario in West Bengal with emphasis on seismic hazard microzonation of the city of Kolkata, India |
| VerfasserIn |
S. K. Nath, M. D. Adhikari, S. K. Maiti, N. Devaraj, N. Srivastava, L. D. Mohapatra |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Sciences ; 14, no. 9 ; Nr. 14, no. 9 (2014-09-25), S.2549-2575 |
| Datensatznummer |
250118670
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| Publikation (Nr.) |
 copernicus.org/nhess-14-2549-2014.pdf |
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| Zusammenfassung |
| 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 Assam–Arakan 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 (Vs30 ~ 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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