Saturday | 5 October 2024 | Reg No- 06
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Saturday | 5 October 2024 | Epaper

We must brace to face strong earthquakes

Published : Sunday, 7 May, 2023 at 12:00 AM  Count : 520
Md Zillur Rahaman
An earthquake was felt at 5:57 am in Bangladesh time on Friday (5 May 2023). According to the USGS, its magnitude was 4.3 on the Richter scale and its epicentre was 14.2 km east-southeast of Dhaka's Dohar and 23.4 km south-southwest of Azimpur. Moreover, its origin was at a depth of 10 km below the surface. Many of us remember the recently hit February 6, 2023 earthquake of magnitude 7.8 in Turkey. It has wreaked havoc in Turkey and Syria. Just a minute earthquake! At the moment, everything was devastated. It was in Turkey along with the border towns of neighbouring Syria. Death toll exceeds 50,000 in 'century's worst' earthquake to strike Turkey-Syria border. More than 44,000 have died in Turkey alone, and nearly 6,000 have died in Syria.

It is known that in the last 485 years, 52 mild, moderate and severe earthquakes occurred within 200 km of Bangladesh. A total of eight earthquakes have occurred around Dhaka in the past era alone. The epicentres of these earthquakes were Narayanganj, Mymensingh, Manikganj, Narsingdi and Dohar. Even though Bangladesh has not been hit by a major earthquake, geologists have repeatedly advised to be cautious and aware of the causes and consequences of large and strong earthquakes in the future, from the recent mild and moderate earthquakes.

Analyzing the causes of earthquakes, it can be seen that earthquakes are mainly caused by natural and man-made or artificial causes. Among the natural factors - firstly, the earth's crust is composed of many small and large moving plates. Earthquakes occur along plate boundaries as a result of the movement of two such plates towards each other or opposite to each other. These tectonics are the main cause of earthquakes all over the world. For example - along the Pacific volcanic belt, in the Alps - Himalayan rift region, in the mid-ocean ridge etc., tectonic plate movement is the main cause of earthquakes. Second, H. F. Ried proposed the theory of elastic recoil as the cause of Earth's devastating earthquakes. According to him, sudden earthquakes occur when rock breaks and slips along the fault due to strong stress on the rock layer due to ground movement. Thirdly, earthquakes are felt during volcanic eruptions. Generally, when a volcano erupts with an explosion, strong earthquakes are felt in the surrounding area. Fourth, when the amount of water vapour stored underground becomes excessive, it pushes the bedrock with great velocity.

As a result, earthquakes are felt. Due to the numerous rifts in the adjacent part of the Pacific Ocean, internal steam earthquakes are often observed. Fifth, since creation the hot Earth is gradually cooling through heat radiation.

Although the surface of the Earth is cold and hard, the interior is still very hot. As a result, the volume balance between the upper and lower layers is lost, so some parts of the surface are sub ducted to create folds to maintain the balance. Earthquakes can occasionally occur during such rearrangements. Sixth, earthquakes are felt at the top of the earth's surface, especially in mountainous areas, when landslides and large rock piles fall down steep slopes. Seventhly, large masses of ice break off from the snow-capped summits of high mountains and fall down with great velocity, known as glaciations. This causes mild earthquakes to be felt. On the other hand, among the man-made causes of earthquakes - firstly, various countries have nuclear explosions almost underground at present. As a result, severe earthquakes were felt in the surrounding area of the blast centre. Secondly, if artificial reservoirs are constructed by damming the river, the water stored in the reservoir will be under heavy pressure and if the geological structure of the place is not stabilized, earthquakes may occur. For example - 1967 earthquake occurred due to the pressure of stored water in Koina Dam in Koina Nagar, Maharashtra.

Earthquakes are very difficult to predict. Researchers cannot diagnose a specific earthquake directly, but through micro seismicity research, focal mechanism research, they can predict and determine risk areas, hyper seismicity, loseismicity, which is very helpful in preventing loss of life and property along with increasing public awareness.

According to experts, it is essential for the government to have a clear action plan to deal with earthquake related disasters. Bangladesh is one of the most earthquake-prone countries in the world due to poor infrastructure, unplanned urbanization, non-compliance with required building codes and widespread construction of buildings and structures despite not being part of the Bangladesh Plate Boundary.

Since earthquake is a natural disaster, it cannot be stopped. Mild and moderate earthquakes are harbingers of strong earthquakes and we need to be aware and alert now by learning from smaller earthquakes.
The writer is a banker and columnist


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