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A Summary Report on Muzaffarabad Earthquake, Pakistan

by

Dr. A. Naeem, Dr. Qaisar Ali, Muhammad Javed, Zakir Hussain, Amjad Naseer, Syed Muhammad Ali, Irshad

Ahmed, and Muhammad Ashraf

Earthquake Engineering Center at the Department of Civil Engineering, N-W.F.P. University of Engineering

and Technology, Peshawar, Pakistan

General Information

An earthquake of Magnitude Mw= 7.6 occurred on October 8, 2005 at 08:50 am local time causing

damage and casualties over an area of 30,000 km2in the N-W.F.P. province of Pakistan and parts of

Pakistan-administered Kashmir. The main event was followed by more than 978 aftershocks of

Magnitude Mw= 4.0 and above, as of October 27, 2005. The epicenter of the main earthquake waslocated at a latitude of 34 2935N and longitude of 73 3744E. The focal depth of the main

earthquake was determined to be 26 km (USGS). This was the deadliest earthquake in the recent

history of the sub-continent resulting in more than eighty thousand casualties, two hundred thousand

injured, and more than 4 million people who have been left homeless. The adverse effects of this

earthquake are estimated to be larger than those of the tsunami of December 2004.

The major cities and towns affected are Muzaffarabad, Bagh and Rawlakot in Kashmir and Balakot,

Shinkiari, Batagram, Mansehra Abbotabad, Murree and Islamabad in Pakistan (Figure 1). Figure 2

shows a general view of the destruction caused by earthquake in Muzaffarabad.

Almost all the buildings, mainly stone and block masonry laid in cement sand mortar with RC slabs

or GI sheet roofing, collapsed in the areas close to the epicenter. In regions approximately 25 kms

away from the epicenter nearly 25% of the buildings collapsed and 50% of the buildings were

severely damaged. The structures in the affected region are primarily unreinforced stone, concrete

block and brick masonry, and reinforced concrete frames with concrete block or brick masonry infill

panels.

Performance of Unreinforced Stone Masonry Buildings

A significant number of casualties and injuries in the affected region was associated with the

complete collapse of single story unreinforced stone masonry buildings. The stone masonry walls

consisted of irregularly placed undressed stones mostly rounded that were laid in cement sand, mud

mortar or even dry in some cases (Figure 3). Features of construction which appear to be responsible

for widespread collapse of buildings are:


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Stone masonry buildings were more common in the villages (75% of the building stock) thanin the cities (15% of the building stock). The quality of mortar and stones used and the level

of workmanship were very poor due to the poor economic situation of the people. The most

commonly used mortars consisted of 1 part cement to 10 part sand. The approximate

crushing and shear strength of such mortar is 300 Psi and 5 Psi respectively. The rounded and

smooth stones in addition to the poor quality of mortar rendered a very loose bond between

the stones which made the structures extremely vulnerable to earthquake forces.

No horizontal bond beams were provided at the levels of plinth, or roof. Lintel beams wereprovided only above the openings and were not run continuously along the perimeter of the

walls.

No vertical members of concrete or wood were provided in the walls and therefore thecollapse of a particular portion of the wall progressed in an uninterrupted manner to other

portions of the walls and buildings.

In some cases, certainly due to economic constraints, the stones were observed to have beenlaid even dry (no mortar at all) and the gaps were filled by small pieces of stones, leaving thewalls extremely vulnerable to horizontal ground shaking.

Performance of Unreinforced Solid Concrete Block Masonry Buildings

Concrete block masonry buildings with 6 inch thick walls were widely used in the cities (about 60%

of the buildings) and villages (about 25% of the buildings) in the affected area (Figure 4). Solid

concrete blocks 6 inches thick, 6 inches wide and 12 inches long were laid in cement sand mortar.

The collapse of these block masonry buildings in urban areas (more than 60%) was responsible for

the major portion of deaths and injuries in the cities. The most probable reasons for failure were

observed to be:

Poor quality of concrete used for fabrication of blocks, rendering low strength blocks. Poor quality of mortar. Inadequate thickness of walls (6 inch) which were the main shear resisting elements. No integrity of the wall in the transverse direction Weak connections at corners

Performance of Unreinforced Brick Masonry Buildings

By and large brick masonry buildings performed relatively better than the stone or concrete block

masonry buildings. Unreinforced single and two story brick masonry buildings, with RC slabs as

roofing, comprise 25% of the total building stock of the cities near the epicenter. It was observed

that only 30 % of these building collapsed, while the rest suffered only slight damage. The brick

masonry buildings were only constructed by well-off people because the unit cost of brick masonry

was higher than that of other forms of masonry in the area. It was observed that along with better


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Figure 2: Destruction in Muzaffarabad caused by the earthquake of October 8, 2005.

E icenter

Figure 1: Map showing areas affected

by the earthquake of October 8, 2005


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Figure 3: Failure of unreinforced stone masonry walls in Muzaffarabad.Figure 3: Failure of unreinforced stone masonry walls in Muzaffarabad

Figure 4: Collapse of unreinforced concrete block masonry houses in Kamsar near

Muzaffarabad (Latitude N34o24.6 and Longitude E73

o28.5)


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``

Figure 5: Severely damaged unreinforced brick masonry wall in Muzaffarabad

Figure 6: Collapse of Sangam Hotel, a 5 story RC frame building in Domel, Muzaffarabad

(Latitude N34o21.3 Longitude E73

o28.3)


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Figure 7: Formation of plastic hinge in the column near

the beam-column joint in a hospital building in Mansehra

Figure 8: Massive landsliding occurred in the north of Muzaffarabad

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