Dhaka, the capital of Bangladesh, is vulnerable to earthquake disasters due to spontaneous urbanization, high population density, haphazard growth of high-rise buildings, unplanned infrastructure, etc. Besides these, inadequate disaster management plans make Dhaka more vulnerable to disaster risk if a seismic tremor of magnitude 7 or over on the Richter scale occurs. An effective earthquake disaster prevention program is required at organizational levels to minimize the risk of disaster.

Earthquake risk in Dhaka city

Dhaka is vulnerable to earthquake disasters for several reasons.

Located in risky seismic zone

Bangladesh has been divided into three main earthquake zones. According to the seismic zoning of Bangladesh, Dhaka falls into Zone 2, that also includes Rajshahi, Natore, Magura, Meherpur, Cumilla, Brahmanbaria, and Feni. Here, the Chittagong-Comilla-Dhaka and Tangail areas have a possible earthquake risk of magnitude of 6 on the Richter scale.

Unsafe structures

The government of Bangladesh has developed national building codes, which include detailed guidelines for earthquake-resistant design of concrete and steel structures. However, these codes are not officially enforced. Due to the lack of effective enforcement mechanisms, it is feared that many new structures do not maintain the necessary requisites for earthquake-resistant construction. Therefore, the number of unsafe structures in Dhaka city is increasing.

Furthermore, many high-rise buildings and garment factories are being constructed in Dhaka without following the rules. Furthermore, not leaving adequate open spaces while designing buildings also increases the risk of casualties if structures collapse due to earthquakes. Besides these, a significant portion of the structures of Dhaka city have encroached upon the streets and roadways, making those infrastructures more vulnerable for passersby and commuters during earthquakes.

As a result, after a major earthquake of magnitude 7 or over on the Richter scale, these structures can collapse, block streets, hinder rescue operations, and bring the greatest devastation to Dhaka city.

High population density

The population density is very high in Dhaka city. With more than 23.9 million people, and an average of 38,000 people per square kilometer, Dhaka is one of the most crowded cities in the world. As the city is expanding quickly, many new buildings, bridges, roads, and other infrastructure are being constructed to fulfill the needs of this big population.

Millions of inhabitants of Dhaka city live in poorly made buildings.

Soil type

Geographically, Dhaka city is made of soft, wet delta soil, which makes the structures more vulnerable to earthquakes.

Some effective organizational measures to mitigate earthquake disaster risk in Dhaka city

As an earthquake is a natural disaster, it cannot be prevented. However, adequate measures at national, organizational, and individual levels can minimize the loss of lives and property. Here the organizational measures will be discussed.

Decentralization

Dhaka is the center of the economy and administration of Bangladesh. Therefore, Dhaka's risk in the context of the earthquake can make the economic stability, and public administration of Bangladesh vulnerable.

Therefore, decentralization of key financial and administrative activities can minimize the damage if Dhaka faces any major earthquake.

Planning for water and airways

If a major earthquake occurs, the existing road communication system in and around Dhaka can be affected, but the effect will be less in waterways. So there should be a plan to restore the existing waterways (canals, rivers in and around Dhaka) for use during the earthquake emergency period.

Dhaka city is surrounded by three rivers, Buriganga, Sitalakhya, and Turag. These rivers can be again turned into the lifeblood of the city. These rivers need extensive dredging to ensure navigability around the year. The city's circular riverway can be a very useful communication route.

Furthermore, helicopters can also perform during emergency response. This will be an effective way in the field of rescue and emergency services distribution.

Build earthquake-resistant structures

If the structures are not earthquake-resistant, severe damage to lives and properties can occur after an earthquake of 7 or more magnitude hits the city.

To minimize the risk of earthquake destruction, earthquake-resistant buildings should be built.

The city authority can create strict regulations and make it obligatory for planners, engineers, and architects to consider earthquake-resistance capacity while making plans and designs.

The common steps of building earthquake-resistant structures include creating flexible foundations; building shear walls, moment-resisting frames, and diaphragms; building Seismic Invisibility Cloak; using earthquake-resistant materials, etc.

Seismic hazard mapping and database preparation

It is essential to develop a comprehensive regional database of all recorded historical earthquakes in and around Dhaka city. A comprehensive regional seismic hazard map of Dhaka city should be prepared to incorporate appropriate building codes.

Resources such as scientists, seismologists, geologists, engineers, architects, planners, GIS experts, remote sensing experts, and other technicians should be prepared through higher education and relevant training programs to build leadership in earthquake hazard assessment research in Bangladesh.

Building code and vulnerability zoning

It is necessary to ensure that the Bangladesh National Building Code (BNBC) is being followed for construction activities in Dhaka city. Seismic instruments should be installed and operated at suitable locations in the city. The vulnerable buildings should be identified and retrofitted to make them seismic-resistant.

Emergency preparedness master plan

A comprehensive earthquake disaster management master plan needs to be formulated by considering the devastating seismic hazards for Dhaka. The master plan should emphasize community awareness building and earthquake vulnerability zoning.

The master plan should also consider arrangements for rescue teams, necessary recovery equipment, fire extinguishing equipment, and manpower. There should be good coordination among information communication, critical services, local-level volunteering, and government activities.

Fire hazard prevention

Secondary hazards, such as fire hazards from gas and electricity lines, might have a more disastrous impact after a major earthquake.

Therefore, adequate fire protection systems should be maintained while building structures. The buildings should have adequate fire exits and fire safety equipment to minimize the risk of casualties.

Awareness building

Mass awareness among the general public regarding earthquakes should be undertaken on different media platforms such as television, radio, newspapers, etc.

City residents should be encouraged not to panic, what to do if an earthquake hits, where to get shelter, where to call for help, etc.

Extensive mass awareness programs for earthquakes can be arranged targeting diverse professionals such as government officials, engineers, architects, designers, builders, medical professionals, etc.

Civil-armed force cooperation

Civil-military collaboration is an important consideration in the field of earthquake emergency response. Community volunteers, civilians, and armed forces can work jointly in post-earthquake disaster rescue, recovery operations, and provision of emergency services.

Voluntary disaster management organizations at the local level

The local communities under different wards of Dhaka city should be organized and capacitated. It is necessary to form Disaster Preparedness Committees at Ward levels. Such Committees can be organized with respected people in the community, such as teachers, Imams, social workers, health professionals, local elite, businessmen, etc.

Besides these, volunteer groups can be formed with the participation of the younger generation, including scouts, and interested students.

Training is necessary for proper volunteer activities focusing on knowledge-sharing on earthquake disasters; and producing a work plan for ward-based Disaster Preparedness Committees.

Information sharing and communication

There should be efficient communication systems and information-sharing networks among stakeholders, such as general people, government, and community-level organizations.

The availability of critical services should be ensured by the responsible authorities and organizations to minimize the impact of earthquakes.

Assessment of public and private facilities

It is necessary to assess the fire-fighting strengths, arrange appropriate training programs, and stock essential fire-fighting equipment.

Furthermore, an assessment should be done to determine the logistic capacities of the city corporation, such as the available trucks to carry debris, emergency water supply facilities, rescue equipment, etc.

It is important to assess the capacity of hospitals and other medical centers in terms of the availability of doctors, nurses, medicine, and equipment stock, to deal with large casualties.

Besides these, an assessment of existing blood banks is necessary. Developing a database of blood donor lists with contact addresses and blood groups will be helpful during emergencies.

Rescue equipment

Arrangements of essential rescue equipment is a necessary step to meet the needs of emergency response. So necessary steps should be taken to collect and store the modern rescue equipment. Such measures will help to carry out recovery operations effectively at the time of response.

Alert system

An efficient earthquake alert system and transmission of information to the local community can minimize the damage to lives and properties.

Conclusion

Dhaka, the capital city and financial hub of Bangladesh, is one of the fastest-growing megacities in the world. The economic growth and huge population, including growing labor, fuel extensive construction of multi-story buildings in the city. Therefore, decentralization can reduce the burden of damage on the economy and minimize death tolls.

Many multi-story buildings and factories have been constructed in Dhaka without proper earthquake consideration. The risks of earthquake fatalities can be minimized by building earth-quake-resistant structures, seismic-hazard mapping, database creation, and strict enforcement of the Bangladesh National Building Code.

An earthquake emergency preparedness master plan is necessary to stay prepared for earthquakes. Mass awareness should be created as part of earthquake preparedness. Besides these, proper information sharing, and coordinated efforts of government, armed forces, and civil and voluntary organizations can ensure effective rescue operations and minimize casualties.