Bangalore: The city was abuzz with rumours on Friday morning about a low intensity earthquake in parts of the city after residents experienced a mysterious sound and rattling.

Speculations were rather specific and even strangely consistent: that a quake measuring 1.5 on the Richter scale hit Kengeri, HSR Layout and Yelahanka at about 8.30 a.m. These were, however, quickly put to rest by the meteorological centre here, which said it was more likely a quarry blast.

The centre received several calls, a majority from media organisations, according to its director A. Muthuchami.

"We have checked with authorities in Chennai and New Delhi and both have said there was no seismic activity," he said. Moreover, earthquakes never occurred in isolated places across the city, he added. "The only possible explanation can be that they were quarry blasts."

There was also speculation that it could be a sonic boom, a loud noise that is created by shock wave produced by an aircraft travelling at supersonic speed.

Tejaswini R., resident of Yelahanka, said she heard window panes rattle loudly, while Arun Kumar, who lived in Kengeri, said he heard an inexplicable thud on the front door around the same time.

"I heard a loud noise around 9.15 a.m. It thundered in my ears for three to four seconds. I thought that it was an effect of earthquake. I still don't know what it was," said P. Ranjini, a resident of an apartment in Raju Layout, near Kengeri Satellite Town. Vasudeva Sharma, president of Child Welfare Committee, too heard the sound around 8.45 a.m. at S.D Layout near Konanakunte.

Meanwhile, the city police were flooded by calls from public asking whether it was an earthquake.

It was a busy morning for policemen attached to J.P. Nagar, Kengeri, Basavanagudi, Chandra Layout, HSR Layout, Bidadi and other stations.

"It was really a tough time for us. We deployed almost all our staff to check the origin of the sound, but no information was available," said an officer attached to J.P. Nagar police station.

On the other hand, the staff at the HAL police station said the sound could be from fighter aircraft. "Usually, two or three fighter aircraft fly over the city for training every day. On Friday too, we saw aircraft on the western parts of the city."

However, this speculation too was put to rest as officials of the Hindustan Aeronautics Limited and the Indian Air Force stated that there was no flight which experimented supersonic speed.

"Tremors were recorded at the broadband station of the Indian Institute of Science at about 10 a.m.," T.G. Sitharam, Professor, Civil Engineering Department, told The Hindu. "But it is too early to know the magnitude and whether they were created by an earthquake or a quarry blast."