The loud noises reported in various locations across the island, including Orchard Road and Bukit Timah, at about 11.30am yesterday were possibly caused by planned detonation activities carried out by the Singapore Armed Forces at the Southern Islands.
The police said in a Facebook post that they have verified with the Ministry of Defence on the detonation activities, which started at 11.45am and ended at 1.30pm.
They advised the public not to be alarmed.
Reader Jessica Choo-Tan, 40, told The Sunday Times that she heard two "explosion-like" sounds and felt some vibrations just before 11.30am in Owen Road in the Novena area.
She said a friend who lives next to Novena MRT station also heard the sounds and felt the vibrations.
"But other than the sounds, I didn't spot anything unusual," she said, adding that she heard another loud noise about 30 minutes later.
My sliding windows were rattling in their frame and, at first, I thought there was some construction work going on.
A LAWYER, who gave her name as Nicole, who lives in the Newton area.
I thought it was thunder and felt the ground shake a little.
MS TRINA LIU
A lawyer who gave her name as Nicole, who lives in the Newton area, said she "felt the house shake" at around noon.
"My sliding windows were rattling in their frame and, at first, I thought there was some construction work going on," she said.
She felt a second round of vibrations about half an hour later but it was "less violent than the first".
Several Facebook users said in response to the police post that they heard the sounds in areas such as Hougang, Lim Chu Kang, Aljunied, Queenstown, Bugis and Woodlands, with some suggesting that it was weather-related.
Ms Trina Liu wrote: "I thought it was thunder and felt the ground shake a little."
On April 12, several people living in the eastern suburbs reported on social media that they heard a loud noise and some tremors in the wee hours of the morning.
These were later attributed to effects from a fire and explosion at a Petronas oil and gas facility in Johor at 1.25am that injured two men.
• Additional reporting by Rahimah Rashith