ESTIMATION OF PEAK HORIZONTAL ACCELERATIONS FOR THE SITE OF MUZAFFARABAD USING DETERMINISTIC APPROACH

The site of Muzaffarabad is situated in the NW Himalayan Fold – and – Thrust Belt Pakistan, which occupies a 250 km wide and about 560 km long, irregularly shaped mountainous region stretching from the Afghan border near Parachinar, up to Kashmir Basin situated in the active zone of convergence thereby recording a large number of seismic events. Quite a large number of seismically active tectonic features like Main Mantle Thrust (MMT), Main Boundary Thrust (MBT), Mansehra Thrust, Jhelum Fault, Kotli Thrust, Raikot Fault, Thakot Fault, Riasi Thrust, Sangargali Thrust, Hissartang Fault and many others are located within this fold and thrust belt. Historical as well as Instrumental seismological data collected in the present study confirms the active nature of all these faults. In the present work, peak horizontal accelerations have been estimated for the site of Muzaffarabad using deterministic approach. The selection of this site has been based primarily due to the fact that this site is representing the location with heavy population, high seismicity and surrounded by active tectonic features. A total of twelve faults have been considered as a critical seismogenic features to the area and their maximum potential magnitudes and seven available attenuation equations, peak horizontal accelerations have been determined. On the basis of these maximum potential magnitudes and the peak horizontal accelerations, Main Boundary Thrust having peak horizontal accelerations of 0.47 g has been designated as the most hazardous for the site of Muzaffarabad.