1 seismic disaster mitigation in pakistan dr. qaisar ali associate professor and deputy director...
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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
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