The earthquake that was reported in Dhaka and adjoining districts on Saturday, originating near the plate boundary and the Comilla-Tripura fault line, was notably strong.
It caused considerable fear in Comilla, leading to rushed evacuations and injuries to over a hundred workers. The quake also resulted in damage and cracks to buildings in several areas, including Dhaka University's Mohsin Hall.
The earthquake was relatively enduring, lasting approximately 33 seconds. It was determined to be shallow, with its depth within 35km according to the underground focus and epicenter's thickness. Despite this, it released less energy than expected for such a depth, as it exceeded 10-20km, suggesting a deeper focus.
The energy was released slowly from the hypocenter, which is different from the epicenter, through underground layers like mud, soil, and hard rock barriers. Earthquakes release energy over a wide range, and a sudden release through very hard rock would have been more dangerous. This is a pattern observed in previous earthquakes and is also evident in other countries.
However, Md Momenul Islam, a meteorologist and earthquake expert at the Bangladesh Meteorological Department, urged people not to panic but to be prepared to face earthquakes.
He said: “Bangladesh is prone to earthquakes due to its geographical location, as it is surrounded by three tectonic plates. These plates intersect near our borders. For instance, the Himalayas to our north lie on the Eurasian plate, while Bangladesh is situated on the Indo-Australian plate. To our east is the Burmese microplate. All three of these plates are not only very close to our national boundary but also active. Notably, 80% of earthquakes occur along these plate boundaries."
There are three types of earthquakes: severe, moderate and mild. According to the depth of the source, earthquakes can be divided into three types – shallow, intermediate and deep earthquakes.
The epicenter of the earthquake is shallow within 0-70km of the earth's surface.
In this type of earthquake, energy is suddenly released. As a result, the damage will be more. However, if it is below 300km from the depth, then the intermediate. As a result, the damage will be somewhat less. And if it is below 300km, it is identified as a deep earthquake.
Bangladesh may face 7 magnitude earthquake soon
Experts said that strong earthquakes are likely to occur in Bangladesh's hilly regions, stretching from Sylhet to Chittagong. Additionally, the hilly areas of Manipur and Mizoram in India, as well as Myanmar, are also at risk.
Moreover, if one imagines a line extending south through the Meghna River, passing through Kishoreganj's Haor, to the Bay of Bengal and the Andaman Sea, this area marks the junction of two tectonic plates. Of these, the Burma Plate lies to the east and the Indian Plate to the west.
The upper part of this junction, which extends from Sunamganj to Manipur and Mizoram in the east, is 'locked'. This means that energy is stored in this region.
Momenul Islam, a meteorologist and earthquake expert at the Bangladesh Meteorological Department, said: "Today's earthquake signals us that we are at risk of a major earthquake ahead.”
Echoing this sentiment, Mehedi Ahmed Ansari, a professor of civil engineering at the Bangladesh University of Engineering and Technology (Buet), said: “More than 100 small earthquakes have occurred in Bangladesh this year, along with five earthquakes with magnitudes between 4 and 5 magnitude. These are indications of an impending major earthquake. In other countries, more than 200-300 earthquakes have preceded major ones. The same pattern is emerging in Bangladesh. We could soon experience a major earthquake, likely at a magnitude of 6-7. It is unlikely to be higher, as the region's earthquake history, including the quakes of 1869, 1876, 1885, 1897, and 1930, shows magnitudes between 7 and 8 magnitude. While there is a possibility of an 8 magnitude earthquake, that might not occur for another 300 years.”
He said the expected earthquake could originate from the plate between Dinajpur and Comilla in the northeastern zone of Bangladesh, with Dhaka likely to be the most affected. This is due to its higher population density and the prevalence of more unplanned buildings.
Regarding the nature of the earthquake's tremors, he said: “The epicenter was close to a fault, which intensified the shaking. Currently, there is no cause for immediate concern. However, we must prepare for the possibility of a larger earthquake. If an earthquake of magnitude 7 occurs in Bangladesh, it would be challenging to manage, given our current level of preparedness.”
