Recently, Bangladesh has experienced several minor earthquakes including a mild tremor with a magnitude of 4.2 on Sunday, which have increased fear among the public as experts have long been saying that the country is at risk of a major earthquake.
Amid this fear, a post has been circulating on social media since Tuesday which claims that there is a risk of an earthquake measuring between 5.5 to 6.8 on the Richter scale in Bangladesh in the next 72 hours.
The post has further heightened anxiety among the people.
However, experts have said that this is entirely a rumour and baseless as the technology to predict earthquakes has not been developed yet.
They have advised everyone to remain cautious but not to panic over this matter.
Experts Refute Earthquake Prediction Claims
About the earthquake forecast on social media, Professor Dr Md Zillur Rahman, chairman of the Department of Disaster Science and Climate Resilience, and the dean of the Faculty of Earth and Environmental Sciences at the University of Dhaka, told online news outlet Jago News that it is completely a rumour and baseless.
“As of now, no technology has been developed to predict earthquakes,” he said.
Geologists from other countries have similar views.
Chris Marone, professor at the Department of Earth Sciences at Italy’s Sapienza University of Rome and the Department of Geosciences at the USA’s Pennsylvania State University, told the UK-based media outlet BBC that scientifically predicting earthquakes in advance is very difficult.
“Due to the uncertainties in nature, we often do not get any indication of a major earthquake about to occur,” he said.
Marone pointed out that complexities in the earth's tectonic movements, the constant internal noise and clashes within the earth, which are often loud, make it difficult to discern clear earthquake signals.
This noise gets mixed with daily life sounds such as traffic, construction, and general commotion, making it hard to isolate clear earthquake indications, he added.
The United States Geological Survey (USGS) also states that no one can definitively predict when, where, or of what magnitude an earthquake will occur.
Recent Earthquake Incidents in Bangladesh
Recently, on Sunday at 12:50pm, Bangladesh experienced an earthquake with a magnitude on the Richter scale of 4.2, being categorized as a minor tremor.
Before this, on September 9, another quake with a magnitude of 4.4 was felt.
On August 14 at 8:51pm, various regions of the country, including Dhaka, felt an earthquake with a magnitude of 5.5 on the Richter scale.
Prior to that, on June 16, a mild earthquake of magnitude 4.5 occurred across the country, including the capital. The epicentre was in Sylhet’s Golapganj upazila.
Another earthquake that took place on May 5 this year in Dhaka and its surrounding areas had a magnitude of 4.3 on the Richter scale.
Alarmingly, all of these earthquakes had their epicentres either within the country's borders or nearby.
Tectonic Plates and Bangladesh Earthquakes
According to experts, such mild earthquakes in the country are occurring due to the opposing movements of the Burmese Plate and the Indian Plate.
They also say that there is a significant accumulation of energy at the junction of these two plates, which is seeking a way to release, causing frequent earthquakes.
Experts highlight that Bangladesh is located in an earthquake-prone zone. The amount of energy accumulated beneath it suggests the potential for a major earthquake in the country.
Professor Dr Syed Humayun Akhter, a former professor of the Department of Geology at Dhaka University, told BBC Bangla: “This energy will release sooner or later. These minor earthquakes are indicators of that.”
According to geologists, the mountainous region of Bangladesh is home to two tectonic plates, the Indian Plate and the Burmese Plate.
The Indian Plate is moving towards the northeast while the Burmese Plate is moving west, causing a clash between them. However, the junction of these two plates is quite deep.
In areas of Bangladesh, especially in the Sylhet region where earthquakes are frequently occurring, it is at a shallow depth, meaning not very deep.
Do Minor Earthquakes Reduce the Risk of Major Ones?
Many believe that frequent minor earthquakes release the accumulated energy within the Earth, thereby reducing the risk of major earthquakes.
However, experts argue that this notion is not accurate.
The amount of energy stored at the subduction zone or the junction of two tectonic plates is so vast that it could potentially lead to earthquakes with magnitudes ranging from 8.2 to 9 on the Richter scale.
Professor Dr Syed Humayun Akhter told the BBC that even if there are daily minor to medium earthquakes, it would still take two to three years for such a vast amount of energy to be released.
He pointed out that areas located on the “Ring of Fire”, like Japan, Chile, and San Francisco, experience mild earthquakes daily. Yet, news of sudden major earthquakes from these places is not uncommon.
This expert said: “The geological structure that leads to major earthquakes in those regions exists in Bangladesh as well.”
Dr Syed Humayun Akhter further said that when the magnitude of an earthquake increases from one scale to another, the energy increases by a factor of 32.
This means an earthquake of magnitude 4 has 32 times more energy than one of magnitude 3.
Reasons and factors behind frequent tremors in Bangladesh
Experts say that the mountainous region extending from Sylhet to Chittagong in Bangladesh is a potential source of powerful earthquakes. The mountainous areas extending to Manipur, Mizoram, and Myanmar are also considered risky.
If one were to imagine a line from the haor in Kishoreganj, passing through the Meghna River and going south by the Andaman Sea to the Bay of Bengal, it would mark the junction of two tectonic plates.
The plate to the east is the Burmese Plate, and the one to the west is the India Plate.
The upper part of this junction, starting from Sunamganj to Manipur and Mizoram, has become "locked," meaning it has accumulated energy.
The junction of the two plates here is shallow, starting at five kilometres deep in the west and gradually deepening to 25 kilometres in the east.
Professor Dr Syed Humayun Akhter told the BBC Bangla: "The energy accumulated here spans thousands of years. From the historical earthquakes that occurred in this region, and by analyzing various books and ancient stories, we have learned that a major earthquake occurred here between 800-1,000 years ago."
Since then, energy has started to accumulate again, he said, adding that energy equivalent to an earthquake measuring between 8.2 and 9 is stored in this region.
"This energy has to be released someday, whether it is today, tomorrow, or in the next 25 years; there is no alternative," he cautioned.
This researcher said that before a major earthquake, smaller quakes can be observed, indicating that such activity might have been evident several years ago, even 5-10 years back.
He explained: "In the last four to five months, we have experienced three to four earthquakes. These are all mild to moderate tremors. They are occurring in the 'locked' segment of the subduction zone. This suggests a trend of releasing large energy, suggesting a major earthquake can occur anytime.”
“However, we cannot precisely predict when the big quake will occur," he added.
Hidden Fault
A study published by Columbia University in 2016 states that there's a concealed fault in the Ganges and Brahmaputra basin which could cause an earthquake measuring up to 9 on the Richter scale in Bangladesh.
This report refers to this concealed fault as the "Megathrust Fault," located miles beneath the surface and situated at the subduction zone or the conjunction of two tectonic plates.
Professor Dr Syed Humayun Akhter mentioned that there are countless faults in Bangladesh. However, geologists are not too concerned about most of them.
“There are numerous faults in the mountainous regions and even in the flat areas. Yet, these are not deadly," he said.
However, he indicated that the most dangerous is the junction of two plates stretching from Sylhet to Teknaf.
“The energy accumulated in this region over the past 800 to 1000 years has not been released, making this area highly risky,” said Professor Dr Syed Humayun Akhter.
According to him, earthquakes that occur at the subduction zone or the conjunction of two plates are terrifying.
Dr Syed Humayun Akhter expressed concerns about this region, noting its similarity to the high-risk "Ring of Fire" in the Pacific, especially the junction stretching from Sylhet to Teknaf.
“Most earthquakes occurring in the ‘Ring of Fire’ area are often above 7.5 in magnitude and they are always destructive in terms of energy,” he added.
Moreover, the fault line extending from Cox's Bazar to Myanmar had released its energy in 1762 and experts believe that new energy is accumulating there as well.
1962 Quake: Saint Martin's Island rise, tsunami
In 1962, a powerful earthquake of over 8.5 magnitude occurred along the fault line stretching nearly 400 kilometres from Teknaf to Myanmar.
As a result, Saint Martin's Island was raised by three metres. Before the earthquake, Saint Martin's Island was a submerged island.
During the same earthquake, hard rocks were split in the Sitakunda hills, leading to the eruption of mud and sand from below.
This earthquake caused a tsunami in the Bay of Bengal, sweeping away houses by the Buriganga River in Dhaka, leading to the loss of around 500 lives.