A moderate earthquake of 5.3 magnitude struck near the India-Bangladesh border on February 27, sending powerful tremors across Kolkata and several districts of South West Bengal.
The jolts began at 1:22 pm IST and lasted for several seconds, triggering widespread panic. Residents and office workers in high-rise buildings rushed onto the streets as ceiling fans and furniture began to sway.
While no immediate casualties or major structural damage have been reported, the event has reignited fears about the seismic safety of the Bengal Basin.
WHERE IS THE EPICENTRE?
To understand the shake, we first need to know where it starts. An epicentre is the specific spot on the Earth’s surface directly above the region where the rocks break deep underground during an earthquake.
Today’s 5.3 magnitude quake was centred near Satkhira in Bangladesh, just 26 kilometres southeast of Taki in West Bengal. This area sits within the Bengal Basin, a giant bowl filled with kilometres of soft soil.
The science behind this is a massive slow-motion collision. The Indian Plate is constantly pushing north into the Eurasian Plate at about five centimetres per year.
This movement creates immense pressure along fault lines. Think of fault lines as giant cracks in the Earth’s crust. When the pressure gets too high, the land on either side of the crack slips suddenly, causing the ground to shake.
HOW DOES SOIL ACT LIKE A SEISMIC MEGAPHONE?
Geologists are currently monitoring the Sylhet Fault and the Eocene Hinge Zone, the main cracks running through the Bengal Basin.
When these faults slip, they release energy called seismic waves. Kolkata has a unique problem because it is built on soft, water-logged soil rather than solid rock.
This leads to a phenomenon called amplification. In simple terms, the soft soil acts like a megaphone for the earthquake. Just as a megaphone makes a voice much louder, this loose soil catches the seismic waves and makes them much stronger. This is why the shaking feels 50 per cent more intense in the city compared to areas sitting on hard rock.
CAN SATELLITES PREDICT FUTURE RISKS?
While predicting the exact minute of a strike is impossible, Nasa uses satellite technology like the Nisar radar to track how the Earth’s skin is stretching.
These satellites can measure ground movement with millimetre precision from space.
This data helps scientists see which fault lines are under the most stress. For a crowded city like Kolkata, this is vital because of a risk called liquefaction.
This happens when intense shaking causes wet soil to lose its strength and behave like a liquid.
If the ground turns into a jelly-like state, buildings can tilt or sink. Nasa data helps the city plan better for these invisible threats.
