A mini earthquake was felt by communities across Snowdonia which caused a "big rumble sound".
British Geological Survey (BGS) confirmed the Conwy Valley and beyond had suffered an earthquake measuring 1.0 on the Richter scale.
The quake was recorded at a depth of 6km with the epicentre given as "3km north-north-east of the village of Dolgarrog, Conwy".
It occurred at 8:10pm on Sunday 17 October with some believing it to be thunder or a sonic boom.
No local residents had reported the event but one woman said her husband shouted, "what was that?". Another posted on Facebook, "I just muted TV in Trefriw wondering what I heard".
Some people also said that their dogs started barking and growling at the "strange" noise.
One person suggested it was a sonic boom. “Phew, glad it wasn’t just me that heard it!” she added.
Earthquakes recorded at 1.0 are considered to be "micro" and are relatively common in the UK.
However it is the largest in North Wales since September 2019 when a 1.5 quake rattled the village of Beddgelert, Gwynedd.
The most recent one was a 0.9 tremor in the Dolbenmaen area of Gwynedd in January 2020.
A spokespoerson for the BGS confirmed no direct reports had been made of the recent earthquake, "Most small quakes go unnoticed and unreported".