The Earthquake Scenario in Bangladesh
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As Bangladesh is located in a tectonically active much of the country including Chittagong, Sylhet, Dhaka, Rangpur, Bogra, Mymenshing, Comilla, Rajshahi are very much vulnerable to major earthquake disaster. Although, some awareness is raised among a limited groups, due to some recent earthquakes in the region, practically the country is far behind the minimum preparedness level to face such a disaster in any of our cities.
Significant damaging historical earthquakes have occurred in and around Bangladesh, and damaging moderate-magnitude earthquake occur every few years. The country’s position adjacent to the very active Himalayan front and ongoing deformation in nearby parts of south-east Asia expose it to strong shaking from a variety of earthquake sources that can produce tremors of magnitude 8 or greater. The potential for magnitude 8 or greater earthquakes on the nearby Himalayan front if very high, and the effects of strong shaking from such an earthquake directly effect much of the country. In addition, historical seismicity within Bangladesh indicates that potential for damaging moderate to strong earthquakes exist throughout much of the country. Large earthquakes occur less frequently than serious floods, but they can effect much larger areas and can have long-lasting economic, social, and political effects.
Liquefaction is another source of earthquake related damage. During sustained strong shaking, poorly consolidated, water saturated sediments can liquefy and loose their ability to support loads. The foundations and supports of structures built on liquefiable sediments can fail, causing damage or destruction. Much of the country is of loose sandy soil and most of it remains in saturated condition round the year, thereby vulnerable to liquefaction in case of sustained ground motions.
Based on the above discussions, the probable scenario for an earthquake to a scale of M6.5 or above in Dhaka city could cause:
1. Panic among the city dwellers and no knowledge of what is to be done during and immediately after the eq. occurrence.
2. Possible sinking of many of the buildings on filled earth with shallow foundations due to the liquefaction effect.
3. If the eq. occurs during monsoon time possible damage of the Dhaka flood protection embankment due to liquefaction effect causing sudden submergence of a large area.
4. Large scale damage and some collapse of poorly constructed and/or old buildings.
5. Possible outbreak of fire in most of the buildings from the gas lines (the residential ovens are mostly in burning condition from morning to mid-night)
6. Possible damage of power installations and power cut off for indefinite period.
7. Water supply failure as almost all the deep tube wells are run by power, and possible water line damage
8. Damage of roads and blockage of traffic due to falling of debris from collapsed buildings and other installations on or near roads.
9. Some of the hospital buildings may collapse killing a large number of inmates and stopping medical facilities for the disaster victims.
10. Some of the school building may collapse killing and injuring a large number of students
11. An after shock may cause further collapse of many of the already damaged buildings.
12. A few rescue equipment, whatever are available, can not be operated due to the lack of guidance, availability of operators, some will be non-functional, some will be under the rubbles, some can not find access to rescue spots due to road blockage, etc.
13. Limited access from outside as most or the highways/bridges, airport will not be functional.
Although during the last decade much advancement has been achieved in the earthquake engineering, modern science has yet to invent any technology that can predict earthquake. Therefore, we must begin to do whatever we can to be prepared to face such a disaster that can hit us any time. A perfect solution can not be made all on a sudden, like Aladin’s Lamp, but unless we begin dealing with these, the situation will be worse as days past.
What the DER can do?
To address the problem multisectoral, multiagencies, coordinated efforts are essential. The primary role to be played, is the responsibility of the GOB, which is to identify a lead agency to coordinate with a number of lined agencies. The policy issues could be handled mostly at the national level. Planning and implementation issues are to be handled at the local level. In most countries the city municipalities are the focal points for the planning and implementation of such issues.
The donor agencies and the NGOs can play vital roles in the identification of the right activities, prioritizing, coordinating, and expediting the activities and their implementations. They can play as catalyst to the GOB efforts in the mitigation. The NGOs have relative advantages to handle the soft elements such as, public awareness, training, etc. They can also assist the implementation of the hard elements. The donor agencies, can also assist the GOB to access resource and also to procure qualified personnel for technical evaluation, design, and providing recommendations for the right activities both in policy matters and the program implementations. In the post earthquake situation the DER can help the country for quick damage assessment, determination of the individual donors for appropriate assistances, and coordination of the relief efforts with the GOB. The role of the DER for an effective and coordinated approach to the above activities can be very helpful for any affected population.
Broadly, we can classify the approaches in to two categories, i.e., preparedness and response. Some of the preparedness and response, could be activities, are listed below, many of which can be achieved in an accelerated way through DER intervention:
- At the GOB set up a special body, may be within the MDMR (DMB?), to take lead and coordination role.
- Prepare and disseminate special guidelines (like the standing orders) for earthquake
- Launch extensive mass awareness programs for earthquake; the awareness must include city dwellers, government officials, municipality officials, politicians, engineers, architects, designers, builders, medical people, etc.
- Develop appropriate training materials for different groups, such as planners, engineers, contractors, masons, bar binders, volunteers, fire fighters, doctors, nurses, first aid providers, etc. Take training programs at the appropriate levels to impart these trainings.
- Update the Bangladesh Building Code and make the document legal, make it binding for all construction activities.
- Install and operate seismic instrument at suitable locations on the country.
- Develop a comprehensive regional catalogue of all recorded historical earthquakes in Bangladesh and adjacent regions that influence the country’s seismic hazards.
- Prepare a regional seismic hazard map of Bangladesh using the existing information and incorporate appropriate building code.
- Develop Bangladeshi scientists including seismologists, engineers, architects, geologists, and other technicians through training and higher education programs to assume leadership in all aspects of earthquake hazard assessment studies.
- Conduct urban hazard study including microzoning, liquefaction potential survey, vulnerability assessment of individual buildings, etc. for all the major cities of Bangladesh. Also, conduct studies for the city life lines (gas, water and sewerage, power, road access for fire fighters, etc.)
- Conduct special studies on structural soundness of hospitals, fire fighting centers, schools and university buildings.
- Demonstrate retrofitting and introduce motivation program of retrofitting through municipality leadership (for Dhaka City this may be RAJUK).
- Assessment of the fire fighting strengths and take appropriate training, provisioning of appropriate fire fighting equipment, and personnel for individual cities.
- Assessment of the capacity of hospitals and other medical centers to deal with large casualties.
- Assessment of the doctors, nurses, and other technical personnel, and the medical and equipment stock
- Assessment of the rescue equipment stock and their usability at the time of response.
- Delineation of an efficient army and civilian combined rescue operation
- Capacity of the existing blood banks, and development of a large blood donors’ list including database of their contact addresses and blood groups.