Seismic hazard assessment of Muzaffarabad
MonaLisa 1, Azam. A. Khwaja 2 and M. Qasim Jan 1, Ishtiaq A. K. Jadoon 3
1Deprtment of Earth Sciences, Quaid-i-Azam University, Islamabad, Pakistan
2Higher Education Commission, Islamabad, Pakistan
3Department of Environmental Sciences, COMSATS Institute of Information Technology, Abbottabad, Pakistan
The occurrence of the 7.6 Mw magnitude earthquake in north Pakistan in October 08, 2005 has increased the urban earthquake risk in the area due to high rate of urbanization, faulty land use planning and construction, and inadequate infrastructure. The seismic hazard assessment (SHA), which can be conducted in connection with risk analysis in urban areas, can be carried out using the usually adopted methodologies of deterministic and probabilistic approaches. The site of Muzaffarabad has been selected for SHA determination. The SHA was carried out by considering the earthquake source zones, selection of appropriate attenuation equations, near fault effects and maximum potential magnitude estimation.
The city is located tectonically in an active regime referred to the as Hazara-Kashmir Syntaxis. The Main Boundary Thrust, Panjal Thrust, Jhelum Fault, Muzaffarabad Fault, Mansehra Fault, Oghi Thrust, Balakot Shear zone and, further to the south, the Sanghargali, Nathiagali, and Thandiani Thrusts are the most critical tectonic features within the 50 km radius of Muzaffarabad. Compiling the instrumental seismological data from 1904 to 2007, the earlier work of the authors has been revised. Other reactivated critical tectonic features in the area have been investigated. Among them the Balakot-Bagh fault, with the fault length of 120 km from Balakot to Poonch, has been considered as the most critical tectonic feature on the basis of geological/structural/seismological data. The potential earthquake of maximum magnitude 8.0 has been assigned to the Muzaffarabad fault using four regression relations. The peak ground acceleration value of 0.25g (10% probability of exceedance for 50 years) and 0.5g has been calculated with the help of the attenuation equation using probabilistic and deterministic approaches. |
