A deafening boom, trembling floors and terrified residents rushing out of their homes turned an otherwise ordinary Tuesday morning into a scene of panic across Hyderabad's south-western outskirts, after an unexplained burst of sound and ground vibrations rattled several residential neighbourhoods.

Residents across Rajendranagar, Upparpally, Attapur, Erraboda, Keshavswamy Nagar and Langar Houz reported the incident at around 10.25 am on October 27.

The vibrations reportedly lasted five to 10 seconds, rattling windows and shifting household utensils, leaving many people wondering whether an earthquake had struck the city.

As alarm spread across the affected localities, residents stepped out of their homes and gathered in open spaces, fearing that the tremors could signal a larger seismic event.

The sudden, explosion-like noise added to the confusion, prompting speculation about its origin.

However, scientists at the Hyderabad-based National Geophysical Research Institute (NGRI) moved to dispel reports of a major tectonic earthquake, pointing instead to a localised geological process known as hydro seismicity as a possible explanation for the phenomenon.

What caused the mysterious boom?

Experts say that Hyderabad's geological setting offers important clues to understanding the incident. The city lies on a stable crystalline granite shield, making a destructive earthquake highly unlikely.

Nevertheless, localised micro-seismic activity can occur beneath the surface. Water penetrating deep into the ground, particularly amid intense seasonal or persistent rainfall, can enter tiny pores and fractures in underground rock formations.

As water moves through these confined spaces, it can generate hydrostatic pressure and mechanical stress.

When pressure changes or small fractures move suddenly, the accumulated energy may release in a brief burst, producing vibrations and a booming sound.

Granite, being a dense rock capable of transmitting vibrations and acoustic energy, may carry such disturbances to the surface.

Consequently, even a minor subsurface fracture could produce a sound that seems far more powerful to nearby people than the underlying geological event would suggest.

This explanation, however, should not be mistaken for a definitive confirmation of the cause of Tuesday's incident. Scientific verification is needed to determine the precise source of the reported sound and tremors.

No major damage reported

Preliminary assessments indicated no loss of life or significant structural damage to buildings in the affected areas. Municipal and disaster management officials urged residents to remain calm amid the uncertainty.

The episode also brought attention to Hyderabad's history of similar reports. Comparable underground noises and minor tremors reportedly triggered brief panic in the Sulemannagar and Chintalmet sectors in October 2020 and February 2026.

Earlier, in January 2015, a shallow micro-earthquake measuring 1.8 on the Richter scale was recorded near Budvel.

While Tuesday's incident revived fears of seismic activity, the initial scientific assessment pointed away from a major tectonic earthquake.

The episode underscored how sudden underground sounds and vibrations can unsettle entire neighbourhoods, even when initial assessments reveal no significant damage.

For residents who felt their homes shake, however, the brief disturbance was enough to turn a routine morning into an unnerving experience.