In the recent past the nation has been traumatized by the worst possible man made human disaster of the history causing death to 1117 garment workers maiming and seriously injuring hundreds at Rana Plaza, Savar. This was due to collapse of a building whice was very poorly designed. We can expect collapse of many more buildings of such poor structural design and using poor quality of material. After that what will be the human tragedy can’t we visualize? The most required equipments are supposed to be the ones to needed rescue the people from collapsed buildings. But, are we prepared /equipped?
Bangladesh’s Position in Earthquake Zone
Tectonic frame work of Bangladesh and adjoining areas indicate that Bangladesh is situated adjacent to the plate margins of India and Eurasia where devastating Earthquakes have occurred in the past. Non-availability of Earthquake geological and tectonic data posed great problem in earthquake hazard mapping of Bangladesh in the past. Historical seismic catalogues (ISET, 1993) reveal that Bangladesh has been affected by earthquake disasters since ancient times. Earthquakes occurring in 1664, 1828, 1852 and 1885 are shown to have Dhaka as the epicenter. However occurrence of earthquakes both inside and outside of the country and around major cities indicates that earthquake hazard exists for the country in general and the cities in particular.
Past History of its Effect in Bangladesh
Consideration of earthquake forces in structural design, city planning and infrastructure development is therefore a prerequisite for future disaster mitigation. Unlike most natural disasters, earthquake affects millions of square kilometers in a very short time, which in most cases, is less than a minute. As it catches everybody in an unprepared state, earthquake tops the list of all natural disasters in producing damages and death. The 12th June 1897, Great Indian earthquake of magnitude 8.5 affected whole of Bangladesh and produced severe damage in northern, central and eastern parts of Bangladesh. The 15th January, 1934 Bihar Nepal earthquake affected only northern parts of Bangladesh. As Bangladesh is the world’s most densely populated area, any future earthquake shall affect more people per unit area.
Structure and surface geology of Bangladesh are related to its tectonic evolution which started when the northward moving Indian plate collided with the Eurasian plate. The collision caused the northern extremity of Bay of Bengal to separate into gulfs of Assam and Burma. During second collision at the end of Eocene time, the gulfs were swallowed. The third collision, which occurred in Middle Miocene, was intense due to which folding occurred in the sediments of Chittagong, Sylhet and Assam.
Major Earthquakes effecting Bangladesh
During the last 150 years, seven major earthquakes have affected Bangladesh. Table below shows the date and magnitude for each earthquake. Out of the seven earthquakes, only two (viz. 1885 and 1918) had their epicenters within Bangladesh.
Vulnerability of Cities /Towns of the Districts of Bangladesh
By close examination of the seismic maps it can be seen that, northeastern cities of Bangladesh are more vulnerable to earthquake hazards than the central, eastern, southern, south western and western cities. The most vulnerable cities in the northeast are Mymensingh, Kishorgonj and Sylhet. The north western, central and southeastern cities which include Dinajpur, Rangpur, Dhaka, Comilla, Chittagong and Cox’s Bazaar are comparatively less vulnerable than the fore mentioned cities. The southwestern and western cities are the least vulnerable and include cities like Rajshahi, Faridpur, Khulna and Barishal etc. But Dhaka having 15 million people having the most congested urban population will be worst affected.
What to do during an Earthquake
Stay as safe as possible during an earthquake. Minimize your movements to a few steps to a nearby safe place and if you are indoors, stay there until the shaking has stopped and you are sure exiting is safe.
* Drop to the ground;
* take COVER by getting under a sturdy table or other piece of furniture;
* and HOLD ON until the shaking stops. If there isn’t a table or desk near you,
* cover your face and head with your arms and crouch in an inside corner of the building.
* Stay away from glass, windows, outside doors and walls, and anything that could fall, such as lighting fixtures of furniture.
* Stay in bed if you are there when the earthquake strikes. Hold on and protect your head with a pillow, unless you are under a heavy light fixture that could fall.
* In that case, move to the nearest safe place.
* Use a doorway for shelter only if it is in close proximity to you and if you know it is a strongly supported, load bearing doorway.
* Stay inside until the shaking stops and it is safe to go outside. Research has shown that most injuries occur when people inside buildings attempt to move to a different location inside the building or try to leave. Be aware that the electricity may go out or the sprinkler systems or fire alarms may turn on. DO NOT use the elevators.
* Move away from buildings, street-lights, and utility wires.
* Once in the open, stay there until the shaking stops.
* The greatest danger exists directly outside buildings, at exits and alongside exterior walls. Many of the 120 fatalities from the 1933 Long Beach earthquake occurred when people ran outside of buildings only to be killed by falling debris from collapsing walls. Ground movement during an earthquake is seldom the direct cause of death or injury. Most earthquake related causalities result from collapsing walls, flying glass, and falling objects.
If in a moving vehicle
* Stop as quickly as safety permits and stay in the vehicle.
* Avoid stopping near or under buildings, trees, overpasses, and utility wires.
* Proceed cautiously once the earthquake has stopped.
* Avoid roads, bridges, or ramps that might have been damaged by the earthquake. If trapped under debris
* DO NOT light a match. DO NOT move about or kick up dust.
* COVER your mouth with a handkerchief or clothing.
What to do after an Earthquake
Should expect AFTERSHOCKS
* These secondary shockwaves are usually less violent that the main quake but can be strong enough to do additional damage to weakened structures and can occur in the first hours, days, weeks, or even months after the quake.
* Listen for the latest emergency information. USE the telephone only for emergency calls.
* OPEN cabinets cautiously.
* Beware of objects that can fall off shelves.
* STAY AWAY from damaged areas. Stay away unless your assistance has been specifically requested by police, fire, or relief organizations.
* Return home only when authorities say it is safe
* BE AWARE of possible tsunamis if you live in coastal areas. These are also known as seismic sea waves (mistakenly called ‘tidal waves’). When local authorities issue a tsunami warning, assume that a series of dangerous waves is on the way.
* Stay away from the beach. HELP injured or trapped persons.
* Remember to help your neighbors who may require special assistance such as infants, the elderly, and people with disabilities. Give first aid where appropriate.
* Do not move seriously injured persons unless they are in immediate danger of further injury.
* Call for help.
* Leave the area if you smell gas or fumes from other chemicals. Unnoticed damage could lead to a fire.
* CHECK FOR GAS LEAKS.
* If you smell gas or hear blowing or hissing noise, open a window and quickly leave the building.
* Turn off the gas at the outside main valve if you can and call the gas company from a neighbor’s home. If you turn off the gas for any reason, it must be turned back on by a professional.
* LOOK FOR ELECTRICAL SYSTEM DAMAGE.
* If you see sparks or broken or frayed wires, or if you smell hot insulation, turn off the electricity at the main fuse box or circuit breaker.
* If you have to step in water to get to the fuse box or circuit breaker, call an electrician first for advice.
* CHECK FOR SEWAGE AND WATER LINES DAMAGE.
* If you suspect sewage lines are damaged, avoid using the toilets and call a plumber.
* If water pipes are damaged, avoid using water from the tap. You can obtain safe water by melting ice cubes.
What May be the Effect of Earthquake in Dhaka City
As said by many we expect that many buildings built before adopting National Building Code of Bangladesh 1994 in Dhaka city will badly be affected if an Earthquake of around 7 Richter scale or more occur.
Bangladesh National Building Code is only the first step towards preparation of more refined and up to date zoning map in the near city. Much information on geophysical, geological earthquake and strong motion data are needed for preparation of such comprehensive map. Our biggest hazards will come from Gas pipe lines crisscrossing under the ground of Dhaka city. Each Gas stations having around 100 large storage cylinders will fly like missiles and burst into flame with the impact.. Many structures in the gas stations and industries will collapse and roads under which high pressure gas lines have passed through are likely to buckle and rupture during severe earthquake. In Mohakhali alone there are 6-8 gas stations within a radius of 500 meters. Our industries will be affected badly and economy will collapse if we do not make a comprehensive plan. We must take measures to close the power and gas lines immediately after occurrence. Much more serious infernos can be expected in Dhaka city than that of Magurchara in Sylhet.
Action Plan for Earthquake Disaster Management
A comprehensive action plan shoud be prepared by the Utility Services dep’t. i.e. Gas transmission, Power service and WASA etc. Effective plan should be chalked out to stop the supply of these utilities particularly Gas and power from source and from Sub-stations. This will at least save the life of people after the tremor is over. Earthquake Disaster Management Teams should be organized along with Military, Civil Defense, Fire Brigade, Para Military, law enforcing agencies and local volunteers. Major blocks must be divided into Zones in Dhaka, Chittagong and bigger cities and placed under a team. These organized teams should carry out periodical rehearsal and develop awareness amongst the residence. Necessary equipments must be procured and these teams sould be trained to handle those. US, Japan are the two countries who have a very elaborate system to handle Earthquake disaster happening often in those countries. We may request those countries and International research institution to help us in this regard. The military officers along with civil defense officials should be sent to USA, Japan or other countries to study the effect of Earthquake and how to manage such disaster along with other agencies in collaborations. It is heartening to see that we have such compassionate and dedicated people in the country who make themselves available as volunteers as shown at Rana Plaza tragedy. We should organize/train those people during peace time to handle such national disaster.