Aftershocks Explained In Simple Words

Spread caution and comfort without spreading panic. After surviving every second since November 21, I felt it necessary to take a breath and inform others after the following reasoning. And of course, keep praying to God. There is no other way to save without Him.

How likely is a major earthquake in Dhaka?

On November 21, 2025,- 5.7 magnitude earthquake was the main shock, and today's small tremors (3.3 and 3.7 magnitude) are aftershocks, which were expected.

⭐ This is a normal process - after a major earthquake, the cracks or 'fault lines' underground take some time to stabilize, which results in these small tremors.⭐ However, the signs are good: the magnitude and intensity of the tremors are gradually decreasing (5.7 ➡️ 3.3 ➡️ 3.7). This indicates that the energy underground is being used up and the situation is returning to normal. The risk of an immediate larger earthquake is low.

🔥 Statistical Probability of an immediate large earthquake: Analyzing scientific formulas (Båth's Law and Omori Decay), it is shown that the probability of an earthquake of magnitude 6 or more occurring on the same fault line is less than 1%. Although minor aftershocks or tremors may continue for a few days, their magnitude is unlikely to exceed 4.5.

🔥 Why are these not Foreshocks but Aftershocks?

Analyzing the formulas of modern seismology, it can be said with certainty that the current tremors are basically aftershocks of a magnitude 5.7 earthquake. The main 5 scientific arguments behind this are:

1. Omori’s & Båth’s Law: According to these two laws of science, aftershocks decrease in number and magnitude over time. This is exactly what is happening here—the 3.3 and 3.7 magnitude tremors after the 5.7 are much weaker. If these were foreshocks of a major disaster, the magnitude of the tremors would have been very close to the main earthquake, not so low.

2. Spatial Footprint: All three earthquakes occurred within the same 10-kilometer area (Rupture Patch) of the Madhupur Fault. This proves that no new rupture is being created, but rather the rupture that moved in the 5.7 magnitude tremor is now stabilizing or 'adjusting' (Afterslip). Dhaka is located on soft alluvial soil, which multiplies the shaking of the earthquake (Basin Effect).

3. Base-rate Probability: USGS statistics say that in only 5% of the world, a larger earthquake is followed by another earthquake. In areas between 'intraplates' like Bangladesh, this probability is even lower (2-3%). In other words, there is a 97-98% chance that the worst is over.

4. B-value Analysis: Before a major earthquake, the ratio of small tremors underground, or 'b-value', usually decreases, which indicates an increase in pressure. But in this Dhaka incident, the 'b-value' did not decrease, but increased. This means that the pressure underground is not accumulating, but rather energy is being released and the pressure is decreasing.

5. No Precursors: Before a major earthquake, the rate of tremors usually increases suddenly, or the hypocenter begins to move. No such unusual signs (GPS Anomaly or increase in tremors) were seen in this incident.

🔥 Is there a risk of a major earthquake? (Possibility & Risk)

⭐ Short-term (next few days): The risk of a larger earthquake (such as magnitude 7.0 or 8.0) occurring now or in the next few days is very low (less than 1%). Small aftershocks may occur for a few more days, so there is nothing to worry about.

⭐ Long-term (in the coming years): Bangladesh is located in a highly earthquake-prone area. There is a lot of energy stored in the 'Dawki Fault' (on the border of Sylhet and Meghalaya) and the 'plate boundary'. There is definitely a risk of a large (7.5+) earthquake or the 'Big One' in the future, but it is impossible to say for sure when it will happen.

✅ Advice:

1. Don't be afraid: The current aftershocks are normal. They are not an indication of a major danger, but rather the process of cracks healing underground.

2. Be prepared: Since Dhaka is a risk zone, keep heavy furniture (cupboards, shelves) against the walls in the house against the walls. During the tremors -

⭐ Don't run: Do not try to go down the stairs in a multi-storey building like Dhaka during the tremors. Statistics show that more people are injured while rushing down the stairs than when a building collapses.

⭐ Safe location: When the tremors start, follow the "Drop, Cover, Hold on" method - get down on the ground, take shelter under a solid table or bed, and hold on tightly. The use of elevators is completely prohibited.

🔥 Structural Check:

Check if any cracks have formed in the house due to the tremors in the last two days. It is said that hairline cracks in the corners of doors or plaster are nothing to be afraid of. But if you see any cracks in pillars or beams, especially 'X' shaped cracks, then consult a structural engineer without delay.

The current situation is largely under control; there is no reason to panic. Remember, it is not possible to prevent an earthquake, but proper preparation can save your and your family's lives.