Peak ground acceleration assessment of an imaginary site at Hawks Bay near Karachi
Abstract
Karachi is located near a triple junction where Arabian, Indian and Eurasian plates are interacting. The plate boundaries are loci of earthquakes. The residential and industrial areas coalesce at many places in Karachi. In this geological and social Set up, the determination of antiseismic design parameters are essential in the present study the maximum credible earthquakes and Site specific peak ground acceleration of a sensitive installation like a chemical or a pesticide plant or an oil storage facility have been assessed. For the purpose of this study an imaginary sensitive structure is assumed at Hawks Bay. The methodology adopted is in accordance with IAEA safety guide, no seismites could be recorded in the site vicinity and near regional areas. Surjan Jhimpir fault, Thano Bulla Khan fault zone, Karchat fault and Murray ridge are identified as seismogenic sources on the basis of the historical and instrumental seismicity The Allah Bandfault of Kuch rift zone does not extend through the Kirthar fold and thrust belt and possess no significant seismic risk to Karachi. Intensity V of Mercelli Modified Scale (MMS) is assigned to the large earthquake of the January 2001 after an intensity survey in Karachi. The city area itself is marked by mainly micro seismicity while low to moderate seismicity is associated with seismogenic sources around Karachi. The maximum credible earthquake identified sources have been calculated by the use of regression relationshipfor50% rupture of fault length. The Peak Ground Acceleration (PGA) Of have been assessed by using attenuation relationship. The site specific PGA should be determined for each sensitive installation by following the international criteria.
References
Ahmed, R., & Ahmad, J., 1991. Petroleum Geology and Prospects of Sukkur Rift Zone, Pakistan with special reference of Jaisalmer, Cambay and Bombay High Basins oflndia, Pakistan Journal of Hydrocarbon Research, Vol. 3.
Ahmed, R., Ali, S.M., 1991. Tectonic and structural development of the eastern part of Kirthar Fold Belt and its hydrocarbon prospects Pakistan Journal of Hydrocarbon Research, Vol. 3,
Banks, C.J. & Warburton, J., 1986. Passive -roof duplex geometry in the frontal structures of the Kirthar and Sulaiman Mountain Belts, Pakistan. Journal of structural Geology Vol. 8.
Bonilla, M.G., Mark, R.R., & Lienkaemper, 1984. Statistical Relationship among earthquake Magnitude, Surface Rupture Length and surface Fault Displacement Bull. Seismol. Soc. Vol. 74 No. 6.
Campbell K W., 1997. Empirical Near - Source Attenuation Relatibnship for Horizontal and Vertical components of Peak Ground Acceleration, Peak Ground Velocity, and Pseudo Absolute Acceleration Response Sepec. Sesimological Research Letters Vol. 68, Number 1.
Ellouz, & Lallemant S., 2000. Proposition de campagne a la Mer Chamak Makran-Pakistan, Soumise a La Commission Geosciences Marine de PIFREMER, FRANCE.
Hunting Survey Corporation, 1960. Reconnaissance geology of part of West Pakistan, Toronto.
Husain, E., 1993. Geological map of Pakistan, geological survey of Pakistan Quetta
Kazmi, A.H. & Jan, M. Q., 1997: Geology and Tectonics of Pakistan, Graphic Pub., Karachi, Pakistan.
Malik, J. N. Sohon, P.S., Meih, S.S., karanth, R.V., 2000. Paleoseismology and neotectonism of Kuchchhi western India, In Goto & Takala eds: Active fault research for the new Millennium, proceedings of the Hokudan international symposium and school on active faulting Okumura, Japan.
Mirza, M. A., Babar, M.Z. Farah, A., Ali, S. I., Ali, and K.S., 1984. Seismic risk map of Karachi, Hyderabad and Lasbela districts Pakistan, Geo. logical Survey of Pakistan Quetta,
Molnar, P., and Tapponnier, P., 1975. Cenozoic Tectonics of Asia: Effect of a continental Collision. Science Vol. 189.
Oldham, T., 1882. Catalogue of Indian Earthquakes from the earliest Time to AD 1869. Mem. Geol. Sur, India, Vol. 19, Part 3.
Oldham, T., 1926. The Cutch Earthquake of June 12 1897. Mem. Geol. Sur. India Vol. 46 Part 2.
Outerbridge, W. & Khan, R. A., 1989. The Lákhra anticline and active feature of Pleistocene to Recent age in southern Pakistan: US Geological Survey Circular 1045.
Quittmeyer, R.C., & Jacob, RM., 1979. Historical and Modern Seismicity of Pakistan, Afghanistan, NW India and SE Iran. Bull, Seismol. Soc, Vol. 69
Quittmeyer, R.C„ Farah, A., & Jacob, K. G. 1979. The seismicity of Pakistan and its relation to surface faulting, A. Farah and K. A. DeJong eds. Geodynamics of Pakistan GSP Quetta.
Raza, H, A., Ali, SM., Ahmed, 1990. Petroleum Geology of Kirthar Sub -Basin and Part of Kutch Basin, Pakistan Journal of Hydrocarbon Research, V. 2. No. 1
Sadigh, K., Chang, C., Egan, J.A., Makdist F., &Ÿoungs, R.R., 1997. Attenuation relationships for shallow crustal earthquakes based on California strong motion data Seismological Research Letters Val, 68, Number I
Slemmon, D.B., Bodin, P., Zhang, X., 1989. Determination of earthquake Size from surface faulting events, Proc. Inter. Seminar on seismic zoning, Guanghou, P. R. China,
Tahirkheli, R.A.K., Mattauer, F., Prooust, C., & Tappoinier P., 1979. The Indian Eurasian suture zone in northern Pakistan A. Farah and K.A Dejong eds, Geodynamics of Pakistan, GSP Quetta.
Zaigham, N., Naqvi, S.W. H., Ahmed, M., 2000. Low magnitude earthquakes of Karachi city during August-Sept. 1998, Geologica, 5., Geoscience labs Pakistan.
