Risk of major earthquake looms in near future

Frequent earthquakes in a short span have made residents of Narsingdi, Dhaka, and nearby areas anxious. Do these quakes signal a major one ahead, or has the risk eased? Syed Humayun Akhter, former professor of geology at Dhaka University and an earthquake researcher, discusses the recent tremors and Bangladesh’s future risks. The interview was taken by Khairul Kabir Chowdhury.

Question: Four earthquakes in a short time, all with epicentres inside the country—in Narsingdi and Dhaka. Does this indicate something new?

Answer: First, Friday morning’s 5.7-magnitude quake in Madhabdi, Narsingdi occurred at the boundary of the Indian and Burma plates. This boundary runs across Sunamganj, Kishoreganj, the Haor region, then down the Meghna River to the Bay of Bengal—a subduction zone.

In a subduction zone, one plate slides beneath another. Here, the Indian plate is going under the Burma plate. A massive amount of energy has accumulated and is waiting to be released. Our research shows this zone has stored energy equivalent to an earthquake of magnitude 8.2 to 9.

The 5.7 quake means a point in the locked zone opened slightly, releasing a small portion of energy. The two quakes on Saturday, morning and evening, happened north of Friday’s epicentre, along the same line at the plate boundary.

Question: So the stored energy is trying to come out?

Answer: Yes, a large amount of energy is trying to escape. A small portion came out through an opening. Then two more quakes struck 5–10 km north the next day. This suggests the stored energy is trying to break through its locked path. This means more quakes could occur farther north or south. It may not be today or tomorrow—there may be a 10-day gap—but once a wider path opens and the blockage weakens, a major release could happen.

Question: Some say aftershocks mean the major quake already happened and that the risk is now lower. Is that true for Narsingdi?

Answer: No. As I said, the subduction zone holds energy for a magnitude 8.2–9 earthquake. The recent quakes reflect signs of that stored energy. Only about 0.1 percent of the energy was released. So a huge amount remains. We cannot assume no major quake will occur. In fact, these quakes indicate the possibility of a larger one in the future.

Question: What if Friday’s quake had been stronger than 5.7?

Answer: If it had been 6.5 or 7, then around 50–55 percent of the stored energy might have been released. In that case, I would say the risk of a major quake would be lower, with only some aftershocks expected.

Question: Can we estimate where or when the feared major earthquake may occur, or which areas are most at risk?

Answer: Since this started in Narsingdi, the stored energy could be released within 15–30 km north or south of the epicentre.

Question: That sounds worrying for Narsingdi and nearby areas, especially Dhaka.

Answer: Certainly.

Question: Why is the likelihood higher around Narsingdi?

Answer: The entire 250-km stretch from Sylhet to Chattogram is storing energy. The energy will follow any available opening to escape. Not all areas have equal strain, and we don’t know where the exact peaks are—nature knows. It will start where it finds an opening and then may extend sideways or to nearby zones.

Question: We see frequent tremors in Dhaka and surrounding areas. Does this mean a new fault line is forming under Dhaka?

Answer: Stored energy must come out—sooner or later. It escapes through faults. If an existing fault is available, it may use that. Or it may create a new fault. It’s like the “chicken or egg first” question.

Question: What can be done to reduce damage and casualties?

Answer: Awareness and preparedness are crucial. People need regular training on what to do during an earthquake, how to stay safe, where to take shelter, and how to avoid risks from aftershocks after a major quake. Training and drills are essential. Since many people use smartphones, we could develop natural-hazard games to teach earthquake safety and preparedness in an engaging way.