1ST Round Table Discussion : MAGNITUDE & INTENSITY OF EARTHQUAKE IN BANGLADESH

Recently several newspapers published some primary steps for preparedness for earthquake and risk of Earthquake. But experts opinion regarding present condition and our steps to encounter earthquake in Bangladesh has not been clearly published. In that context, FPD organized a series of five round table discussions jointly with Bangladesh Earthquake Society (BES) to convey the opinion of expert professionals of different walks of the society regarding context of Bangladesh in earthquake and safety measure measures for earthquake in Bangladesh.

The first discussion was held in 29th September, 2010 at Sheltech lounge. It was inaugurated by the president of BD Earthquake society, Professor Dr. Jamilur Reza Chowdhury. He was the chief guest on that first round table. The main moderator was the chairman of FPD, Dr. Taufiq M. Seraj. On behelf of FPD, Engr. Mahmudul Hasan, Engr Tanverul Haque Probal and Engr. Chowdhury Iamal Ashraf were present in that seminar. The main theme was presented by professor. Dr. Moonaj Ahmed Noor, General Secretary, Bangladesh Earthquake Society (BES).

Held on: September 29, 2010.
Venue: Sheltech Lounge, Sheltech Tower.

Participants:
1. Professor Dr. Jamilur Raza Chowdhury, Secretary Bangladesh Earthquake society.
2. Dr. Toufiq M. Seraj, Chairman FPD, Managing Director, Sheltech
3. Dr. Moonaj Ahmed Noor, General secretary, BES
4. Dr Aftab Alam Khan, Department of Geology, DU
5. Professor Dr. T M AL Hossaini, Department of civil engineering, BUET
6. Engr. Abdul Mojid Shikder, Additional Chief Engineer, PWD
7. Engr. Chowdhury Jamal Asraf, Director FPD
8. Engr. Abdul Malek Shikder, Superintendent Engineer, PWD
9. Engr. Nurul Islam,Executive Engr, Rajuk
10. Engr. Md. Saidur Rahman,Rajuk

The Supporting Participants:
1. Muhammad Ariful Islam, Research Coordinator, Forum For Physical Development (FPD)
2. Nazmul Ahsan, Research Officer, Forum For Physical Development (FPD)
3. Nilima Nasrin, Research Officer, Forum For Physical Development (FPD)
4. Mamun Chowdhury, Research Officer, Forum For Physical Development (FPD)

On that conference Engr, Tanverul Haque Probal, Director of FPD thanked everyone. The main topic was about causes of earthquake, probability of Earthquake in Bangladesh, intensity and magnitude of earthquake in Bangladesh. A lively and vivid presentation was made through various explanations.

Dr. Toufiq M. Seraj,Chairman FPD,Managing Director, Sheltech
FPD is a non profitable private organization. It is not a NGO, there are seven entrepreneurs of this organization. The aim of this association is to make applied research on various aspects of Physical development and publish it so that the research can be used as basis of further research in future. The main characteristic of this organization is only it explores the findings based on the opinion and given information of experts of concerned fields of research.
Last few months, several accidents occurred all over the country especially in Dhaka; for instance, in our capital city, there were many incidents of building collapse, killing and injuring people and properly loss. Another terrible incident was devastating fire hazard at Nimtoli and so on. Later, several earthquakes hit the country a few days interval. Though, no hazardous event was occurred, it has raised anxiety among the general people.
These panics among mass people have been created due to lack of knowledge regarding earthquake and its impact, existing condition of our country against earthquake etc. In this circumstance, this round table has been arranged to attain a publication based on opinions and given information of experts that would be conducive to people in research filed.

Jamilur Reza Chowdhury,President, Earthquake Society
Newspapers have published various news, some news is right and some are erroneous. Bangladesh earthquake society was registered in 2002. In the past, earthquake was not much emphasized. Flood, Cyclone, Tornado etc. natural calamities got much priority over than earthquake for preparedness purpose. Now, earthquake is getting importance. Damage and other loss of property due to earthquake mainly depend on the strength of building or infrastructures. In our country, Building code is named as BNBC 1993. Yet its effective implementation has not been started.
Economic condition in Chili is much well now. In 1960, preparedness for earthquake was not enough, so people had to face enormous loses. But now the earthquake of 2010, could not damage much of their property.
There is risk of damage at present. But many says, nearly 80% to 90% Buildings would be destroyed which is not true at all. So the main responsibility of media is not to represent such erroneous information but only true and reliable news to the people.
There is a misconception abut return period, among people. Such as 200 year return period of a earthquake does not mean that earthquake of same intensity and dimension would occur. Rather, it means there is a probability to occur one within next 200 years.
RADIOUS was a project of IMDR in1998. A study was conducted over 20 cities and it is found that Dhaka is the most risky city. If we increase our capacity and lessen our vulnerability, then earthquake vulnerability will dwindle to a great extent.

Dr. Munaj Ahmed Noor,General Secretary, BES,Professor, Civil Engineering, Department, BUET
Some terrific and Erroneous news published on several news papers.
According to a govt. investigation, an earthquake at 7.5 Richter scale at Madhupur fault will kill 1, 31, 029 people and injure more than 32, 948 people. Another investigation says that about 10 important hospitals will be completely destroyed and 241 hospitals & clinic will be severely damaged.
A Difference between magnitude and intensity.
Magnitude refers to the amount of energy released from earthquake source; each earthquake has its definite magnitude. But some earthquake may have different dimensions of intensity in different places. The more the distance form the center of earthquake is, the lesser the intensity will be.
There are different types of plate convergences such as plate Boundary, Divergent Plato Boundary, Gas transform plate boundary. Convergent plate boundary has three types.
i) Oceanic to oceanic
ii) Oceanic to continental and
iii) Continental to continental
Indian subcontinent falls in this zone of continental to continental plate boundary. Big earthquakes mainly occur within this plate boundary.
It is very essential to know the maximum limit of earthquake happening in this sedimentation, because if the sediment can not retain the energy above 6/7 intensity of earthquake, it also will fail to release that energy.
There is very few evident of earthquake at high intensity in Bangladesh. So it can be safely predicted about little occurrence of earthquake impact in Dhaka. For example, The Richter scale of Great India earthquake was 8.7 in 1897, but when it appeared towards Dhaka, its intensity became nearly 6 at Richter scale. Similarly, in 1885, earthquake of 6.8 intensity occurred at Madhupur fault whereas, its intensity was measured appropriately 6 in Dhaka. Likewise, earthquake of 7.6 intensity hit Srimongol in the year of 1918 whose intensity was above 7 in Dhaka. That means, last 500years, it is found that only one earthquake happened intensity level above 7 after having observed the previous records of Earthquake in Dhaka.
We only talk about Hazard. But risk of Earthquake depends both on vulnerability and capacity. Earthquake risk varies at different degrees due to change of any one of capacity or vulnerability. This relationship can be expressed as:
CDMP determined five main faults for Bangladesh These are PBF-1, 2,3, Modhapur fault and Dauki fault. Return periods (Recurrence Period of Earthquake at same intensity) in PBF -1, 2, 3, Modhupur fault and Dauki fault are respectively 900 years, 349 years and 350 years.
From the point of view of Hazard, Dhaka is not as risky as other cities like Asam, Ahmedabad etc. But in the context of vulnerability, Dhaka is very risky. Because asset or building stocks of Dhaka is much vulnerable compared to other counties. The term Capacity is closely interlinked with physical planning, social capacity, and economic capacity, management capacity in an integrated wary. In this case, our capacity is not as much as other countries, so it can be stated that Dhaka city is much vulnerable considering the above facts.
Earthquake of 7 or 8 at Richter scale is called major earthquake and when, it crosses the limit of 8, then, it is called Great earthquake.
In Bangladesh, there are 3 centers of Major earthquake.
Bengal Arakan earthquake of 1762. Its center is situated between Shitakundo and Cox’s Bazar. This center is a threat for Chittagong.
Bengal Earthquake happened in 1885. Earthquake center was near Bogra fault, Manikgonj. As the center is near Dhaka, it is also dangerous for the capital. Srimangal earthquake of 1918

Dr. Aftab Alam Khan, Professor, Geology Dept. Dhaka University
There are many advanced strategies to determine Hazard, such as: New deterministic Hazard Model. Many organization of our country are now working with this tool, even CDMP is still now working with an old model, probabilistic model which is very uncertain. Change of Any one parameter can differ hazard greatly.
Vulnerability can be expressed by fragility curve. It is a statistical curve that can be drawn in two ways, one is damage and other is vulnerability. A structure is how much vulnerable that can be expressed by fragility curve.
Using the above method, earthquake risk can be calculated finding out hazard, vulnerability and capacity. In our country, one dimensional analysis is used for earthquake. But in the developed countries, multidimensional analysis is used for measuring. Despite of having scope, we are not using this type of analysis yet.

Dr. Tahmeed M. Al-Hossaini
In our country, generally probabilistic method is used to assess earthquake risk and hazard. But some of those researchers using deterministic method have shown that probabilistic method may sometimes provide contradictory results. So, all researchers should be careful of using right method to get more accurate results.
Moreover, most of the researches in our country conduct one dimensional analysis which is however less effective compared to three dimensional analysis. Developed countries carry out multi dimensional dynamic analysis which gives more realistic result. Researchers should follow their practice even though it is more expensive.

Abdul Majid Sikder
Three dimensional dynamic analysis should be carried out by agencies responsible for earthquake analysis. Though this analysis may require modern technology and therefore higher cost to operate, losses from earthquake could be more if one dimensional analysis carried out and for that realistic picture does not come.

Engr. Chowdhury Jamal Ashraf
To mitigate the after effects of earthquake, infrastructure facilities are most important things to consider. In most of the cases, after the shock, infrastructure facilities (community facilities and utility facilities) are broken down. Therefore, sufferings of the survived people boost due to lack of water, gas, electricity etc. So, in our country, as a part of mitigation strategy, infrastructure facilities should be provided in a planned way that can resist tremor of earthquake.

Malek Sikder
Most of our buildings are constructed maintaining no rules and regulations, most of our cities are growing unplanned, and hence the vulnerability of earthquake is increasing day by day. Recently, some moderate and minor consecutive earthquakes stroke in our country within very few days and made people frightened. We should take the situation as challenge. Now it is time we should make the people aware enough about the devastation of earthquake and about the role of everybody to mitigate the effect from this natural disaster.

Md. Taufique Ali, Senior Staff Reporter, The Daily Star.
Sufficient seminars and conferences should be arranged so that general people can have a proper scenario of risky condition of Dhaka city as well as Bangladesh.
Authentic and scientifically analyzed information regarding earthquake can benefit people in various ways. So the electronic media like radio, Television, newspaper, internet can play an effective role to provide the true information to the mass people.

Engr. Md. Nurul Islam, Executive Engr. Central Division, RAJUK
Immediately DAP is to be implemented following all the rules and regulations strictly.
Rivers, ponds and other water bodies are to be conserved and revived if necessary.
Laws of BNBC are to be followed.
Building contraction act and building construction rule 2008 must be implemented strictly.
Water body conservation law is to be followed.
Building should be designed with the aid of skilled structural engineer and during building construction; this design should be followed properly.
Construction materials are to be tested from reliable research institutes.

Engr. Md. Saidur Rahman, RAJUK
• Earthquake zones should be identified correctly in the new edited BNBC.
• Earthquake hazard map can be prepared after considering Geological Hazard Maps.
• Zonal plan and Height zonal plan can be used for preparation of land use plan.
• Disaster Management should be emphasized more.
• All the committees should be under SOD.
• People can be trained up for encountering the post disaster situation.
• Adequate equipments and tools should be collected for disaster management.
• High rise buildings should be conducted considering Geological data.
Though almost the entire country is a plane land, geological condition of different areas varies from place to place. Therefore, there will be some areas which will be more susceptible to earthquake and there will be some areas which will not. Identifying those locations, developments should be discouraged to areas more susceptible to earthquake and encouraged to areas which is less likely susceptible to earthquake. Areas which are more vulnerable to earthquake can be used as agricultural or productive purposes. Proper policies should be made by concerned agencies to control all the processes effectively.

Engr. Tanveerul Haque Probal
Standard of structures should be fixed by which earthquake resistant buildings will be built. It will be expensive and unreasonable also to make strongest buildings that will able to resist any level of earthquake. So it should be determined the minimum strength of buildings by which minimum level of safety could be achieved in context of our country. It will help people to understand the minimum standard and therefore help to decide the standard that people can afford.
Recently, former BNBC is being reviewed and prepared maintaining the measurement of safety from earthquake. Proper rules and regulations should be made and enforced accordingly so that people may follow the rules appropriately.