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Seismic Disaster Mitigation in Pakistan

Dr. Qaisar Ali

Associate Professor and Deputy Director Earthquake Engineering Center Department of Civil Engineering NWFP University of Engineering and Technology, Peshawar Pakistan

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Roadmap

Basic terminology - hazard, risk, vulnerability and disaster

Factors contributing to seismic disaster mitigation

Hazard assessment in context of the Oct 08 earthquake

Vulnerability of structures in context of the Oct 08

earthquake

Recommendations for seismic disaster mitigation in Pakistan

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Hazard, Risk, Vulnerability and Disaster ?

How these terms are interconnected

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Disaster

An event causing widespread human or material losses which exceeds the ability of the affected community to cope using its own resources

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Disaster risk = Hazard x Vulnerability

Source: Satoru NISHIKAWACabinet Office JAPAN

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Implications of Disasters

A single disaster can wipe

out annual GDP of a

country.

Losses from the current

earthquake

80,000 dead

200,00 injured

4 million homeless

Economic losses more

than USD 5 billionDisaster Reduction is a MUST for Sustainable Development

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Disaster mitigation Pre-earthquake scenario

Realistic hazard assessment

Reducing vulnerability through

Seismic resistant design of

structures.

Implementation of code,

inspection and monitoring

mechanism.

Post-earthquake scenario

Emergency preparedness and

planning

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Seismic hazard zoning of Pakistan and the current earthquake

Geophysical center Quetta, Met deptt. of Pakistan

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Realistic seismic hazard assessment

Realistic seismic hazard assessment is crucial because

placing a low-seismicity region in a high hazard zone will

require construction of costly structures thereby making

them uneconomical. Similarly, placing a high-seismicity

region in a low hazard zone will allow construction of

relatively weaker structures thereby making them vulnerable

to collapse during an earthquake.

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Seismic Vulnerability

Low Seismic capacity of buildings due to low

quality of material, improper design and

construction; buildings constructed on loose

soil, or constructed in areas prone to

liquefaction and land slides etc. will make the

structures vulnerable to collapse during an

earthquake.

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Seismic vulnerability with respect to the Oct 08, earthquake

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Stone masonry buildings constitute around 40% of the total building stock. (20% of it in cities and 80% in villages). Approx 95 % of buildings either completely collapsed or got severely damaged.

Undressed stone masonry Dressed stone masonry

Smooth round stones in mud mortar, or low quality cs mortars, no bond beams, no proper connections

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30% of the total building stock (100% of it in cities, negligible in villages) was un-reinforced cement concrete block masonry having RC roof slab, out of which approx 50% either collapsed or got severely damaged.

Low quality concrete blocks laid in mud mortar, or low quality cs mortars, no bond beams, no proper connections

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Total stock of brick masonry building constitutes around

20%, (100 % in cities, negligible in villages), out of which

less than 5% collapsed and around 15% got severely

damaged.

By and large the brick masonry has performed very well.

Brick masonry building Muzafarabad

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Improper lap length

Less than 5% of the total building stock consisted of RC frame structures with brick or block masonry infill walls., 100% in cities.

Generally performed well, The collapse and damage were found to be the result of improper design, detailing and low quality material.

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Strong-beam weak-column

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Incredible

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Improper lateral reinforcement

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Water tanks collapse occurred as far as 200 km from the epicenter

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Original position of deck

1 meter displacement

Life lines---Bridges

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Pipe lines transmission lines

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Massive land sliding washed out entire villages

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Letter written by Sony, a student in Nepal

Ref: Program on Educational Building, OECD

Approx 17,000 school children killed

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None-existence of seismic design guidelines and building codes. site specific ground characteristics for seismic

design. scientifically determined indigenous material

properties. trained professionals for carrying out

construction activities in seismic prone areas awareness of general public for realizing the

seismic risk. Implementing/regulating and inspection

mechanism for construction monitoring

Issues contributing towards seismic vulnerability

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Emergency preparedness and planning

In the post-earthquake scenario the quantum of disaster can increase enormously due to lack of effective emergency preparedness and planning strategies.

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Measures to be taken to avoid disasters in

future ?

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Short Term measures For the reconstruction of the affected areas, general seismic guidelines and building

recommendations can be adapted from already established international codes.

This should act like an interim code and not as a permanent code for the country.

To develop a proper seismic code for the country will take time.

The enactment of a law for strict enforcement of these recommendations is also

required.

Training should be imparted to the contractors, masons, construction supervisors

and local government hierarchy at the union council and tehsil level for effective

reconstruction and rehabilitation activities.

The design and construction of educational institutions, hospitals and other

important government buildings should be given special attention. The EEC should

be involved in this process.

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Short Term measures---

Construction of new buildings in the areas prone to landsliding

and liquefaction should be avoided.

Rapid assessment of damaged public and private buildings is

crucial. There should be authorized qualified technical

professionals to carry out these activities. (Fear among the

people is so high that even some slightly damaged buildings

have been declared as uninhabitable.)

Repair, strengthening and /or retrofitting of existing buildings

deficient in seismic capacity is also vital.

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Improving the seismic performance of masonry structure-general guidelines (ref Eurocode-8)

Note: such arrangement provide overall integrity and stability to the structure.

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Long term measures Installation of strong motion net work

Development of seismic hazard maps based on PGA and PGV, liquefaction and landslide maps, micro zoning for highly seismic prone regions etc.

Development of seismic code for the country

Seismic risk assessment for various categories of buildings and engineering structures.

Structural assessment of important buildings such as dams, long span bridges, educational institutions, hospitals, secretariat etc and their strengthening, if required.

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Long term measures (contd)

Technology development for low cost base isolation and

damper systems for brittle structures.

Development of repair and strengthening techniques for

seismically distressed local structural systems.

Development of disaster mitigation methodologies.

Seismic risk assessment for sustainability of life lines

including, highways, railways, Gas, Sewerage and Water

pipe lines and electricity transmission lines etc.

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Proverb by Japanese Physics Scientist Dr. Torahiko

“Natural disasters will hit us

by the time people have

forgotten about it”

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Thanks