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Bangladesh - September 20, 2023

Bangladesh at risk of 9 magnitude earthquake

Mahfuja Mukul: Bangladesh is one of the most natural disasters in the world. Natural calamities such as cyclones, floods, droughts etc. cause huge damage to our lives, resources and environment every year. Our geographical location is one of the reasons for these disasters. Earthquake has written a new name in this book. Although mild and moderate earthquakes have been felt in recent times, severe earthquakes have occurred in this region. Scientists are expressing fear that a magnitude 9 earthquake may hit Bangladesh in the near future. They said to prepare for this now.
According to experts, there is a possibility of strong earthquakes in the hilly areas extending from Sylhet to Chittagong in Bangladesh. Along with Bangladesh, India’s Manipur, Mizoram, Myanmar’s mountainous areas are also at risk. Also, if one imagines a line south through the Haor of Kishoreganj through the Meghna River along the Bay of Bengal and the Andamans, the area is the junction of two tectonic plates. Between these two plates, the Burma plate is located in the east and the Indian plate is located in the west. The upper part of its confluence i.e. the region starting from Sunamganj east to Manipur, Mizoram is ‘locked’. That is, energy is stored here.
How much energy is stored – Experts say there is enough energy stored to cause an earthquake of magnitude 8.2 to 9. This energy can come out at any time. Now it’s just a matter of time.
Early signs: 10 earthquakes this year
So far this year (September 17), 10 mild and moderate earthquakes have occurred in the country. Although there is not much loss of life and property, experts are getting a glimpse of a major earthquake.
At the beginning of the year, a large area of Türkiye-Syria was hit by a terrible earthquake. About 50 thousand people died there. Millions of houses were destroyed. On February 5, an earthquake of magnitude 7.8 struck there. Later several earthquakes were felt there.
The first earthquake was felt in Bangladesh this year on February 16. Along with India’s north-eastern state of Meghalaya, Bangladesh’s north-eastern Sylhet district was also shaken. There was no damage to property in this 3.9 magnitude earthquake.
On February 25, a pair of moderate earthquakes hit Myanmar. The earthquake was felt in Ayawati and Rakhine states of the country as well as Cox’s Bazar in Bangladesh. Meteorologist Dr. Md. Abul Kalam Mallik of Bangladesh Meteorological Department said, the origin of the earthquake in Rakhine state was 378 km southwest of Agargaon in Dhaka. Its magnitude was 4.1 on the Richter scale.
An earthquake of 4.6 magnitude was felt in Chittagong on April 30. Meghnath Tanchangya, assistant meteorologist of Chittagong Meteorological Office, said that the place of origin of the earthquake was Latitude 22.93 degrees North, Longitude 94.19 degrees East in Maulai, Myanmar. Its distance was 400 km to the southeast from the earthquake monitoring and research center of the capital.
An earthquake was felt in the capital on May 5. Farzana Sultana, assistant meteorologist of the Bangladesh Meteorological Department, said that an earthquake of 4.3 magnitude was felt in the capital on Friday morning at 5:57:8. Its origin was in Doha, 30 kilometers southeast of the city center of Dhaka. However, there was no damage to property in this incident.
A 3.9 magnitude earthquake hit the Bay of Bengal on June 5. According to Indian media Live Mint, an earthquake of magnitude 3.9 struck the Bay of Bengal this morning. The epicenter of the earthquake was at the bottom of the Bay of Bengal near Myanmar. The depth of the earthquake, which struck around 8:30 am Bangladesh time, was 10 km.
On June 16, an earthquake was felt in various parts of the country including the capital Dhaka. Apart from Dhaka, earthquake information comes from Sylhet, Moulvibazar and Sunamganj. According to the website of Meteorological Department, the place of origin of the earthquake was Golapganj in Sylhet. However, the information that is available in various media immediately after the earthquake says that the place of origin of the earthquake is in Shillong, India.
According to the United States Geological Survey (USGS) website, the magnitude of the earthquake was 5 on the Richter scale. However, Farzana Sultana, assistant meteorologist of the Bangladesh Meteorological Department, said that at 10:46 an earthquake measuring 4.5 on the Richter scale was felt.
On August 14th, a magnitude 5.5 earthquake was again felt in Sylhet. At the same time, it is also felt in some districts of the country including Dhaka. According to information from Earthquake Observatory and Sylhet Meteorological Office, its place of origin was Meghalaya in Assam. Its depth at origin was 35 km. The distance from Dhaka to the place of origin is 228 km north-east.
Exactly 16 days later, i.e. on August 29, a mild earthquake was felt again around the city of Sylhet. Initially, it was known that its magnitude was 3.5 decimal. The epicenter of the earthquake was Jaintapur in Meghalaya state of India.
On September 9, a mild earthquake measuring 4.4 on the Richter scale struck the north-eastern state of Assam in India. Sylhet district of Bangladesh was also shaken by the earthquake that hit Assam. According to preliminary information, the origin of this earthquake is about 43 km below the surface. According to the Earthquake Monitoring Center of Bangladesh, an earthquake of magnitude 4.4 was felt in Sylhet. The distance from Dhaka to the place of origin is 263 km north-east at Cachar, Assam, India.
A 4.2 magnitude earthquake was last felt in Tangail on September 17. Its origin was at Tangail Sadar, 59 km from Dhaka. The depth of the earthquake was 5 km below the surface.
Bangladesh is prone to major earthquakes
Meteorologist and earthquake expert of Bangladesh Meteorological Department. Mominul Islam told that Bangladesh is at risk of earthquake due to geographical location. Because, three tectonic plates passed around Bangladesh. Their intersection is around our border. For example, the Himalayas to our north lie on the Eurasian Plate. Our location is on the Indo-Australian plate. And before us is Burma Micro Plate. All these three plates are our connected and active. The plates have movement. They move about five centimeters or 50 millimeters per year. That means, every year we are moving northeast by five centimeters. In the same way the whole world is also moving.
Movement of earth in three criteria
He said, the movement of the world is being completed in three criteria. The first is convergent movement, i.e. two plates moving in the same direction and colliding with each other. The second is that one plate moves in one direction and the other in the opposite direction. This is called Divergent Movement. The third is lateral movement, i.e. if one of the plates is stable and the other moves. The world is moving on these three criteria.
Plate movement, increasing the height
This meteorologist said, such as Eurasian plate in Nepal and our Indian plate (Bangladesh is located on the plate). Convergent movement of the two plates exists. Convergent movement means one plate is moving towards another plate and one plate is gradually rising. That is, the height of the Himalayas, which is slightly higher than what it was last year. That is why when the plates move and for some reason there is little or no movement there is a possibility of large earthquakes. It can be seen that our plate boundary lines are constantly colliding. Many scientists say that if energy is released as a result of the collision, it is good. And if the energy isn’t released, if there’s a plate boundary, it’s risky. Because, later when there is a large energy release from there, earthquakes can cause massive damage. Because of the three active plates around us, we are at risk of major earthquakes, that’s for sure.
In response to a question, he said, only Bangladesh is at risk here, the matter is not like that. The whole world is at stake. There are many plates all over the world. For example, the Eurasian Plate extends across Europe, reaching as far as Nepal. We are located on the Indo-Australian plate. It extends through the continent of Australia and adjacent oceans to the northeastern Indian subcontinent and adjacent watersheds. The entire plate is moving. As a result, it can be said that the whole world is at risk of earthquakes.
Location of plate boundary within 120 km of border
In response to the question whether Bangladesh is at risk of earthquake or not, he said, from past events, it can be said that where there is a plate boundary line i.e. there is a junction of two plates, there is a high probability of a big earthquake. Since Bangladesh is located very close to the plate boundary (the plate boundary is within 100 or 120 km from the border of Bangladesh), we are definitely at risk. There have been major earthquakes in the region in the past. Since the earth gains energy by moving and releases energy through plate boundaries, it can be said that there is a possibility of large earthquakes in Bangladesh.
Earthquake advance prediction not discovered
Former meteorologist Abdul Mannan told Daily Industry that till now no method/process has been discovered to predict earthquakes. Because it is the internal behavior of the earth and internally late movement energy is exchanged from one plate to another plate or when there is a change in energy due to some reason, earthquakes occur. Earth’s interior, however, is not uniformly created. There is nonuniformity and that is why not all places on Earth are created equal. For example, earthquakes occur regularly in Japan. But Bangladesh or there are many regions where earthquakes do not happen like that.
We are in a strong earthquake area
He said, in the past, there have been massive earthquakes in the eastern and northeastern parts of Bangladesh. That means, we are in an earthquake zone. Now the question is why frequent earthquakes? As it is a vulnerable area, it has been prone to earthquakes at some time of the year or in the past, still remains prone to earthquakes as in the past. Since Bangladesh is at risk, Bangladesh should take as many precautionary measures as possible taking into account past records. Because it is a disaster that has no forecast. We have to be careful ourselves to deal with earthquakes.
Bangladesh is moving towards north and northeast
Abdul Mannan said, due to the presence of tectonic plates, all the places of the world are moving. However, we do not see this movement physically. But practically every year it is moving a few millimeters. Due to that movement, Bangladesh is now moving from south to north and northeast. All regions of the Earth are shifting due to the movement of its own plates. Scientists have identified the mechanism of this movement. So, we are not getting any security that there will be no earthquake in any new area. Due to this lack of security, we have to think about the areas which we thought safe at the moment. Overall, earthquakes are likely to happen three times a month, three times a day. Scientists have not yet brought this natural disaster under their control. The internal affairs of the earth have not yet been brought under monitoring by the scientists of any country. That is why we should all be fully prepared.
What can be done to minimize damage?
In response to a question, the scientist said that the old buildings in Dhaka and Chittagong are slowly collapsing. New buildings to be constructed must be earthquake resistant or comply with building codes. It is mandatory. Because Dhaka is the most densely populated city in the world. It is difficult to say whether the earthquake will happen during the day or at night. That’s why I think alarm system can be added in every building. It means that if the vibration is above a certain level, the alarm will sound. Then people can go to safe place quickly. Apart from this, laws can be enacted if necessary for construction of earthquake resistant buildings. Then it will be seen that even if there is an earthquake, the amount of extensive damage will gradually decrease and it will be possible to avoid loss of life.
Is it possible to predict future earthquakes?
He said that the source of the earthquake is the regular observation of the internal changes of the earth. It is very hard work. The issue of observation is being taken care of by developed countries including the United States. They have installed instruments at a depth of more than 100 meters and are trying to sound an alarm whenever they receive earthquake information. Whenever energy is outburst from the energy stores of the plates, the vibration is started. Scientists keep trying. I think one day scientists will be able to predict earthquakes.
Junction of 3 geological formation plates in Bangladesh
Retired Professor of Geology Department of Dhaka University (DU), Geologist and renowned Geologist and currently Vice-Chancellor of Open University Syed Humayun Akhtar told that according to the geological structure, Bangladesh is located at the intersection of three plates. Bangladesh is bounded by the Eurasian plate to the north, the Indian plate to the west and the Burma plate to the east. Bangladesh is located at the intersection of three plates. The junction of the Indian and Burma plates lies within Bangladesh. That is Sunamganj, extending to the east of the Meghna River through Haor of Kishoreganj. If you look at the Haor of Sunamganj and Kishoreganj, you will see that it runs north-south and falls into the Meghna river. If you draw an imaginary line with it, the Burma and Indian Plates are connected through Sunamganj, Kishoreganj, Meghna River to the south, Bay of Bengal and Andaman. On the other hand, it has the Burma Plate to the east and the Indian Plate to the west. The Indian plate is subducting from Burma along the lines of the Sunamganj, Kishoreganj and Meghna rivers. When one plate sinks under another plate we call it a subduction zone. A subduction zone extends from the mountains of Sylhet to Teknaf and Saint Martin.
Subduction zones are prone to major earthquakes
He said that all the major earthquakes of the world have taken place in this subduction zone. Big earthquakes have occurred in Japan, Chile, Alaska. The geological structure there (subduction zone), the same structure is located in our Bangladesh. Earthquakes in subduction zones are very damaging. A review of history shows that large earthquakes have occurred in and around our subduction zone. Those earthquakes have changed the surface, changing the course of rivers. As a result of the Assam earthquake of 1762, the course of the Brahmaputra river changed and went through the Yamuna river. Earlier, most of the water of this river used to flow through the old Brahmaputra river.
Island of St. Martin rose up to 3 meters
This expert said that big earthquakes raise the earth’s surface somewhere and lower it somewhere. For example, the mountainous region of Chittagong has been created through earthquakes. Mountains are formed when two plates collide. In addition, earthquakes also relocate populations. They are in the history of Bangladesh. Bangladesh has had major earthquakes in the past, that is for sure. For example, the earthquake of 1787 changed the course of the Brahmaputra river. In 1897, 1,627 people died in the Great India Earthquake. Also, the 1762 earthquake occurred in a subduction zone.
That earthquake occurred in Myanmar from Teknaf. Which had a magnitude of more than 8.5. In that earthquake Chidua Island in Myanmar rose up to 6 meters. Prior to 1762, St. Martin’s Island did not exist. It was a sinking island. At low tide there would be a slight wake and sink with the tide. In that earthquake, the island of St. Martin rose three meters. In the same earthquake, mud and sand were released in Sitakunda hills.
Past 3 major earthquakes in eastern part of country
He said, in our area, especially in the eastern part of Bangladesh, there were big earthquakes in the past. The earthquake caused changes in the structure of the land, changes in the course of rivers, and effects on the township. The subduction zone in our region has experienced earthquakes of magnitude greater than 8 in the past. As a result, there has been a change in the surface along with the river channel and population.
Bangladesh has accumulated energy of a magnitude 9 earthquake
Syed Humayun Akhtar said, “We have been conducting research activities with Columbia University since 2003. As Bangladesh is located at the intersection of three plates and we deploy GPS to determine the three-dimensional motion of the plates. Through this, we analyze 14 years of data to determine plate motion measurements. Each plate is moving from one place to another every year. We also quantify the direction the plates are moving, the speed at which the two plates are converging or moving toward each other, and how much energy is being stored in subduction zones each year. We measured these and published the report in 2016.
According to the report, from Sylhet to Cox’s Bazar region, there is an accumulation of energy to cause an earthquake of magnitude 8.2 to 9. This energy can come out at any time. This energy can come out all at once or it can come out gradually. However, 65 to 80 percent of the energy from the earthquakes that have occurred in different subduction zones of the world has been released at once. The rest slowly comes out. A similar situation prevails here.
Earlier, the plates had released their frozen energy through earthquakes at Mainamati in Comilla between 800 and 1,000 years ago. After that, it came to this state by saving new energy. That means, over the past 1,000 years, enough energy has been stored to cause a magnitude 8.2 to 9 earthquake. This energy can come out at any time. Since last year, earthquakes have occurred in several places of the country including Sylhet, Rupganj in Narayanganj. Earthquakes occur in subduction zones. These are the signs of a major earthquake. A major earthquake can happen today, tomorrow, or even 50 years from now.
Dhaka is vulnerable to earthquakes
In this context, he said that Dhaka is the center of the geographical location of Bangladesh. Although the source of the earthquake is 50 to 100 km away from here, Dhaka will be the most affected. Because most people live in Dhaka. There is unplanned, uncontrolled urbanization and extreme lack of awareness among people about earthquakes. The people of this city do not know what to do during an earthquake or what to prepare beforehand. They also don’t know how to stay safe during an earthquake. The government also lacks preparation in this regard.
Although the government has prepared through CBMP in 2008, it is not enough or it is not consistent. The government should do the work of creating awareness among the people. Even if the source of the earthquake is far from Dhaka, Dhaka will be more affected. If there is an earthquake of magnitude 8, then Dhaka can become Mritupuri. Since we have no plan, it will be difficult for us to recover from the devastation of the earthquake.
For this, the pressure on Dhaka should be reduced by planning and the population of the country should be moved to the western region. In this case, the government should undertake effective planning and implement it by forming Resilience Society.
Earthquake prevention with low investment
He said, since major earthquakes are at our doorstep and will happen anytime, we need to be safe in unplanned urbanization and settlements. For that we have to adopt some strategy. We can do it with less money if we wish. General public should be made aware. For example, promoting awareness programs on TV through cartoons. Mobile phones can also be used in this regard. By creating mass public awareness, we can save ourselves from this terrible danger – said this expert.

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