A moderate earthquake that shook Dhaka and several other parts of the country at 10:38 am on Friday has sparked widespread anxiety among city residents, with many fearing the tremor could be a foreshock to a much stronger seismic event.

The Bangladesh Meteorological Department recorded the quake at magnitude 5.7 with its epicentre in Madhabdi of Narsingdi, while the United States Geological Survey (USGS) measured it at 5.5, locating the epicentre in Narsingdi.

Tremors were reported from Chandpur, Nilphamari, Sitakunda, Sirajganj, Narayanganj, Patuakhali, Bogura, Barishal and Moulvibazar, triggering panic as buildings swayed, people rushed outdoors, and emergency phone lines became busier than usual. Many residents of high-rise apartments in Dhaka described the shaking as “sharp” and “frightening,” adding that it lasted long enough to cause alarm.

But what has unsettled many even more is the speculation that Friday’s jolt may have been a foreshock — a smaller-magnitude earthquake that precedes a larger seismic event. In a city as densely populated and infrastructure-heavy as Dhaka, the fear of this possibility has stirred discussions, rumours and growing concern.

Foreshock: A Warning Signal, Not a Certainty

A foreshock is a mild-to-moderate earthquake that occurs before a major quake. However, not every small or medium quake is a foreshock — scientists can only determine whether an earthquake was a foreshock in hindsight, after a larger quake occurs.

In Bangladesh’s context, where seismic stress has been building across several fault zones including the Dauki Fault and the plate boundary between the Indian Plate and the Burmese microplate, geologists have long warned that a powerful earthquake is possible. Dhaka’s rapid urbanisation, weak building standards, narrow roads and high population density make the city particularly vulnerable.

Friday’s tremor has revived these concerns, with many residents sharing videos and messages on social media claiming the quake may be a “warning sign.” Experts, however, caution against panic, urging people to stay prepared while avoiding misinformation.

Main Shock: The Event That Causes Maximum Damage

A main shock is the largest quake in a series and typically causes the most destruction. For Dhaka, a major earthquake — especially one measuring 7.5 to 8.0 or higher — could be catastrophic. Studies by earthquake preparedness organisations have warned that more than 70,000 buildings could collapse in worst-case scenarios, particularly in older parts of the city.

If a major seismic event strikes, the intensity of shaking, combined with high-rise structures clustered closely together, could cause widespread structural failure, fires from gas line ruptures, blocked roads, and delayed emergency response. Hospitals would become overwhelmed within minutes. With many residential and commercial buildings not constructed according to earthquake-resistant standards, the likelihood of severe casualties is significant.

Bangladesh sits at the intersection of several tectonic plates, and experts say a powerful quake is not a matter of “if” but “when.” Friday’s tremor, though moderate, has reminded city dwellers of this looming risk.

Aftershocks: The Follow-Up Jolts That Often Continue for Days

Once a main shock occurs, a series of aftershocks usually follow — sometimes within minutes, sometimes over days or even months. These aftershocks may range from light vibrations to strong shakes capable of bringing down already weakened structures.

For a densely packed city like Dhaka, aftershocks can cause additional casualties by toppling damaged buildings, creating panic-driven stampedes, and disrupting rescue operations. Many communities may be left without access to electricity, water and medical services for hours or even days.

Friday’s tremor did not result in widespread structural damage, but residents feared the possibility of subsequent jolts. Officials from the Met Office urged vigilance but reassured the public that there was no immediate sign of a larger quake.

What If an 8.0-Magnitude Earthquake Hits Dhaka?

An 8.0-magnitude earthquake would be one of the most powerful seismic events possible in this region — and Bangladesh’s existing infrastructure would struggle to withstand it.

If such a quake strikes:

1. Buildings would collapse within seconds, especially older concrete structures, unreinforced masonry buildings, and poorly constructed high-rises.

2. Gas lines, water lines and electricity connections would likely rupture, causing fires, explosions and flooding.

3. Roads would become impassable, blocking ambulances and rescue teams.

4. Communication networks may collapse, leaving millions unable to call for help.

5. Hospitals would fill instantly, stretching emergency capacity far beyond its limits.

However, immediate actions can save lives:

Drop, Cover and Hold during the quake: Take refuge under a table or sturdy furniture; protect your head and neck. Do not run outside during the shaking.

Stay in an open area if outdoors; move away from buildings, electric poles, flyovers and trees.

Turn off gas and electricity after the shaking stops to prevent fires.

Use stairs, not elevators, when evacuating buildings.

Keep emergency kits with water, dry food, medication, a flashlight and a whistle.

A Wake-Up Call for Dhaka

Friday’s earthquake may not have caused major damage, but it has exposed the capital’s deep vulnerability. Experts say preparedness, public awareness, strict enforcement of building codes and coordinated emergency planning are crucial to reducing the future death toll.

As Dhaka residents recover from the morning’s scare, the tremor stands as a reminder that the city must urgently prepare for a disaster that scientists believe is inevitable.