Kaghan Valley (Pakistan) earthquakes of February 14, 2004: source mechanism, intensity distribution and their impact
Abstract
Two moderate earthquakes of magnitude ML 5.6 and 5.4 occurred in the Kaghan Valley of northern Pakistan on February 14, 2004. The events were located in Mansehra District near the town of Paras, about 30 km NNW of Muzaffarabad. The seismic and geologic data of the area suggest that the tectonic movement was concentrated in upper crust down to a depth of about 10 km. The composite focal mechanism solution of the earthquakes, using combined polarity data of a local network and global stations, indicates dominantly thrusting with orientation striking 335o NNW-SSE and dipping 55o in NE direction. The isoseismic map shows that the lateral extent of the intensity contours did not extend significantly far from peak intensity VIII on Modified Mercalli Intensity scale near Paras trending in NWSE direction. Most of the damage took place along the strike of the seismogenic fault. Sharp relief and loose/thin fluvial filled narrow valleys further added to the damage. After about 20 months of these earthquakes, on October 8, 2005, a devastating earthquake occurred about 10 km north-west of Muzaffarabad at a depth of about 13 km. The orientation of the Kaghan Valley earthquakes is similar to the orientation of the main shock of the Muzaffarabad earthquake and coincides with that of the Kashmir Thrust.
References
Ali, Z., Mahmood, T., Qaisar, M., Shah, M.A., Iqbal, T., Serva, L., Michetti, A.M., Burton, P., 2009. The Muzaffarabad, Pakistan, earthquake of October 8, 2005: Surface faulting, environmental effects and macroseismic intensity. Geological Society London Special Publication (accepted for publication).
Havskov, J., Ottemöller, L., 2001. SEISAN: The earthquake analysis software. University of Bergen, Bergen, Norway.
Hussain, A., Yeats, R. S., MonaLisa, 2008. Geological setting of the 8 October 2005 Kashmir earthquake. Journal of Seismology, doi: 10.1007/s10950-008-9101-7 (http://www.springerlink.com/content/j5x5u0685 8l57267/).
Kazmi, A. H., Jan, M. Q., 1997. Geology and Tectonics of Pakistan Graphic Publishers, Karachi.
Molnar, P., 1984. Structure and tectonics of the Himalaya: Constrains and implementations of geophysical data. Annual Reviews, Earth and Planetary Science Letters, 12, 489-518.
MonaLisa, 2009. Recent seismic activity in the NW Himalayan fold-and-thrust belt, Pakistan: Focal mechanism solution and tectonic implications. In: Rekheler, K., Michetti, A. M., Silva, P.G (Eds.), Paleoseismology: Historical and Prehistorical Records of Earthquake Ground Effects for Seismic Hazard Assessment. Geological Society London Special Publication (in press).
MonaLisa, Khwaja, A. A., Jan, M. Q., Yeats, R. S., Hussain, A., Khan, S. A., 2008. New data on the Indus Kohistan seismic zone and its extension into the Hazara-Kashmir Syntaxis, NW Himalayas of Pakistan. Journal of Seismology, doi: 10.1007/s10950-008-9139-6. (http://www.springerlink.com/content/0u4764 4337055737/).
Seeber, L., Armbruster, J., 1979. Seismicity of the Hazara arc in northern Pakistan: Decollement versus basement faulting. In: Farah, A., DeJong, K. (Eds.), Geodynamic of Pakistan. Geological Survey of Pakistan, 131-142.
Seeber, L., Armbruster, J., Farahatullah, S., 1980. Seismic activity in the Tarbela Dam site and surrounding region. Geological Bulletin University of Peshawar, 13, 69.
Suetsugu, D., 1997. Source mechanism practice: Lecture notes. International Institute of Seismology and Earthquake Engineering,
Japan.
Tahirkheli, R.A.K., 1996. Tectonostratigraphic domains of northern collisional belts in Pakistan. Map, Geological Survey of Pakistan, Quetta.
Treloar, P. J., Rex, B. C., Guise, P. G., Coward, M. P., Searle, M. P., Windley, B. F., Petterson, M. G., Jan, M. Q., & Luff, I. W., 1989. K – Ar and Ar – Ar geochronology of the Himalayan collision in NW Pakistan: Constraints on the timing of suturing, deformation, metamorphism and uplift. Tectonics, 8, 884–909.
