Hyderabad: A sudden, deafening explosion-like sound followed by localised ground vibrations triggered widespread panic across several residential colonies in the south-western fringes of the city on Tuesday morning, October 27.
The incident, which occurred at approximately 10:25 am, was reported from a wide cluster of areas, including Rajendranagar, Upparpally, Attapur, Erraboda, Keshavswamy Nagar and Langar Houz.
Terrified residents abandoned their houses and rushed into the open streets as the ground shook for nearly five to 10 seconds, rattling windows and shifting household utensils.
Scientists at the city-based National Geophysical Research Institute (NGRI) quickly moved to dispel rumours of a major tectonic earthquake, attributing the occurrence to a localised geological phenomenon called “hydro seismicity.”
Experts explained that Hyderabad sits safely atop a stable crystalline granite shield, making a destructive earthquake highly unlikely.
However, a micro-seismic process occurs when intense seasonal or persistent rainwater percolates deep into the earth. The water saturates the subsurface, forcing its way into the microscopic pores and tiny fractures of the underground granite shelf.
As gravity drives the water deeper into compressed rocky gaps, it creates massive hydrostatic pressure and kinetic stress.
When these trapped pockets of compressed air and water rapidly shift, or cause millimetre-scale ruptures along miniature subsurface faults, the accumulated energy is released instantaneously.
Seismologists noted that because dense granite is an exceptional conductor of kinetic and acoustic energy, even a minor, structurally harmless fracture deep beneath the surface creates a deceptively massive booming sound and immediate ground vibration directly above the site.
Municipal and disaster management officials have urged the public to remain calm. Preliminary assessments indicate no loss of life or significant structural damage to buildings.
The region has a documented history of such swarm-type micro-tremors. Similar subsurface noises and minor shocks caused brief panic in the nearby Sulemannagar and Chintalmet sectors in October 2020 and February 2026, while a shallow micro-earthquake measuring 1.8 on the Richter scale was recorded near Budvel in January 2015.
