Disaster Prevention

Bangladesh is a part of the Bengal basin which is one of the most seismically active zones of the world. Lying as it does in the confluence of the India, Burma and Eurasia plate, the land is extremely prone to earthquake disasters and in the past have experiences some of the worst earthquakes in the history. However, a relatively long period of "rest" from any major hazards and high attention paid to other disasters such as cyclones, floods, etc. have led to both neglect and denial of earthquake as the most destructive of all natural disasters.

Although the world experiences millions of earthquakes every year, few are felt because of their low intensity and magnitude. In general there is a severe earthquake every year (more than 8), 10 large quakes and 100 moderate quakes. The movement of the earth's plates which forms the thin outer shell of the earth's crust causes earthquake. Bangladesh is in such a location.

The point of origin for quakes within the earth is called focus and the point immediately above the focus is called the epicenter. Shallow earthquakes occur 70 km. below the surface while deeper ones happen 600 km. below.

The two measures for earthquakes are intensity and Magnitude. Magnitude measures the energy released which is generally based on the Richter scale measurements. Intensity measures the scale of damage. So an earthquake of the same magnitude may have different intensities depending on the havoc caused.

Chronology of Major Earthquakes
1548 The first recorded earthquake was a terrible one. Sylhet and Chittagong were violently shaken, the earth opened in many places and threw up water and mud of a sulphurous smell.

1642 More severe damage occurred in Sylhet district. Buildings were cracked but there was no loss of life.

1663 Severe earthquake in Assam, which continued for half an hour and Sylhet district was not free from its shock.

1762 The great earthquake of April 2, which raised the coast of Foul island by 2.74m and the northwest coast of Chedua island by 6.71m above sea level and also caused a permanent submergence of 155.40 sq km near Chittagong. The earthquake proved very violent in Dhaka and along the eastern bank of the Meghna as far as Chittagong. In Dhaka 500 persons lost their lives, the rivers and jheels were agitated and rose high above their usual levels and when they receded their banks were strewn with dead fish. A large river dried up, a tract of land sank and 200 people with all their cattle were lost. Two volcanoes were said to have opened in the Sitakunda hills.

1775 Severe earthquake in Dhaka around April 10, but no loss of life.

1812 Severe earthquake in many places of Bangladesh around May 11. The earthquake proved violent in Sylhet

1865 Terrible shock was felt, during the second earthquake occurred in the winter of 1865, although no serious damage occurred.

1869 Known as Cachar Earthquake. Severely felt in Sylhet but no loss of life. The steeple of the church was shattered, the walls of the courthouse and the circuit bungalow cracked and in the eastern part of the district the banks of many rivers caved in.

1885 Known as the Bengal Earthquake. Occurred on 14 July with 7.0 magnitude and the epicentre was at Manikganj. This event was generally associated with the deep-seated Jamuna Fault.

1889 Occurred on 10 January with 7.5 magnitude and the epicentre at Jaintia Hills. It affected Sylhet town and surrounding areas.

1897 Known as the Great India Earthquake with a magnitude of 8.7 and epicentre at Shillong Plateau. The great earthquake occurred on 12 June at 5.15 pm, caused serious damage to masonry buildings in Sylhet town where the death toll rose to 545. This was due to the collapse of the masonry buildings. The tremor was felt throughout Bengal, from the south Lushai Hills on the east to Shahbad on the west. In Mymensingh, many public buildings of the district town, including the Justice House, were wrecked and very few of the two-storied brick-built houses belonging to zamindars survived. Heavy damage was done to the bridges on the Dhaka-Mymensingh railway and traffic was suspended for about a fortnight. The river communication of the district was seriously affected
(Brahmaputra). Loss of life was not great, but loss of property was estimated at five million Rupees. Rajshahi suffered severe shocks, especially on the eastern side, and 15 persons died. In Dhaka damage to property was heavy. In Tippera masonry buildings and old temples suffered a lot and the total damage was estimated at Rs 9,000.

1918 Known as the Srimangal Earthquake. Occurred on 18 July with a magnitude of 7.6 and epicentre at Srimangal, Maulvi Bazar. Intense damage occurred in Srimangal, but in Dhaka only minor effects were observed.
1930 Known as the Dhubri Earthquake. Occurred on 3 July with a magnitude of 7.1 and the epicentre at Dhubri, Assam. The earthquake caused major damage in the eastern parts of Rangpur district.

1934 Known as the Bihar-Nepal Earthquake. Occurred on 15 January with a magnitude of 8.3 and the epicentre at Darbhanga of Bihar, India. The earthquake caused great damage in Bihar, Nepal and Uttar Pradesh but did not affect any part of Bangladesh. Another earhquake occured on 3 July with a magnitude of 7.1 and the epicentre at Dhubri of Assam, India. The earthquake caused considerable damages in greater Rangpur district of Bangladesh.

1950 Known as the Assam Earthquake. Occurred on 15 August with a magnitude of 8.4 with the epicentre in Assam, India. The tremor was felt throughout Bangladesh but no damage was reported.

1997 Occurred on 22 November in Chittagong with a magnitude of 6.0. It caused minor damage around Chittagong town.

1999 Occurred on 22 July at Maheshkhali Island with the epicentre in the same place, a magnitude of 5.2. Severely felt around Maheshkhali island and the adjoining sea. Houses cracked and in some cases collapsed.

2003 Occurred on 27 July at Kolabunia union of Barkal upazila, Rangamati district with
magnitude 5.1. The time was at 05:17:26.8 hours.

Zones of Vulnerability: In Bangladesh, concern regarding the destructive capacity of earthquakes was linked to the protection of major industrial and infrastructural constructions especially those with foreign funding. This led to preparation of vulnerability zoning maps. At present, Bangladeshis divided into three zones with north and northeast-Sylhet, Mymensingh and Rangpur, etc. in Zone 1 which is the most vulnerable. Zone 2 which runs across the middle of the country from northwest to southeast includes Dhaka, Chittagong, Dinajpur, Bogra, Tangail, etc. and zone 3 which is considered less risky, but as parts of an active zone no part is fully safe. Zoning also changes according to the movement of the plates and energies generated by the same.

Although there is an observatory in Chittagong, the situation of that institution is dismal. It is practically not functioning. In fact, few scientific activities regarding earthquakes are underway in Bangladesh. However, the capacity of global level observatories are very high and it is possible for these to communicate with Bangladesh via Internet and satellites until something more sustainable is established here. It should also be noted that despite efforts, the capacity to predict earthquakes has yielded poor results so the main work is monitoring the activities of the plate and preparing the people.

Some Bangladeshi scientists studying the problem believe that seismic pressure since the last major quake has built up quite high and it is possible that an earthquake of 7 to 8 magnitude on the Richter scale may hit Bangladesh anytime between 1998 to 2005.

Vulnerabilities: Vulnerabilities are caused by many factories and some experts think that cities are more susceptible to damage than rural areas which do not have high structures. Falling structures in the urban areas, buildings made by poor masonry, or construction of houses in areas which are subject to soil liquefaction constitute immediate dangers as a results of tremors. Liquefaction means the settling of loose soil which has a high water content. Urbanization has forced development of housing in many areas where the soil is not ready for construction especially multistoried ones or where adequate piling has not been carried out to prepare the ground.

The Government of Bangladesh set up a committee in 1992 to prepare a Building Code, setting the minimum standards which had to be met to construct a house. However, this has not been turned into a law as yet. After the Guzrat earthquake the government has setup committee to recommend action but the preparation level is still extremely low.

In case an earthquake strikes, the utilities such as electricity, water, gas, etc. will be badly affected and some may become threats to life and resources as well. Gas and electricity originated fires have generally killed hundreds of people, sometimes more than the victims of collapsed buildings or masonry. Burst water pipes also create extreme health hazards as unclean water spreads diseases rapidly. The capacity of the response mechanism, if low, makes such vulnerability into mega hazards. A general breakdown of the socio-economic structure will accelerate the economic deprivation. That will again create another set of vulnerabilities. It is now accepted that pre-disaster planning is much more useful than post-disaster mitigation. Many recommended actions are found in plan books of earthquake sensitive countries. However, in Bangladesh, this isn't the case.

The most critical part of any disaster prevention is public awareness which is basically absent in Bangladesh. In order to create a situation which may reduce vulnerability, an organized plan, based on already existing recommendations taking into account the various stages of preparation, should be made. There are many manuals and informative documents available for earthquake management but few are used or accessed and the threat of earthquake is not recognized in Bangladesh. This is, despite the fact as many fear that the next and inevitable earthquake may hurt millions of people.

 

Source: Bangladesh National Report 
Progress of implementation of the Habitat Agenda (1996-2001)
Unlocking the Potential, National Strategy for Accelerated Poverty Reduction (PRSP)
Government of the People’s Republic of Bangladesh
Bangladesh Environment Facing the 21st Century:SEHD
Peoples Report 2002-2003: Unnayan Shamannay
Compendium of Environment Statistics of Bangladesh: BBS