There has been a small earthquake on the Lancashire coast, the British Geological Survey (BGS) has confirmed.
A small earth tremor was felt in the Blackpool area at about 0330 BST, it said.
Lancashire Police said calls had been received from several people who said their properties were shaking.
A BGS spokesman said the 2.2 magnitude tremor was thought to have centred on Poulton-le-Fylde. No damage or injuries have been reported.
A police spokesman said they confirmed reports from 10 callers when the force's control room on Bonny Street, Blackpool, began to shake.
Officers were sent to check reports of cracks on the road over a bridge in Lytham Road, but learnt they appeared up to two years ago.
A spokeswoman for Blackpool Council said structural engineers would assess if there was any fresh damage to the road but it remained open to traffic.
She added there were no reports of any damage elsewhere in the borough, including at the council-owned Blackpool Tower.
Dave Thornton, a gift shop owner from Thornton Cleveleys, was woken up by the quake.
"All my wardrobe doors were rattling and I couldn't work out what it was.
"I went to the window, but everything seemed normal. It was a relief to be honest to learn that it was a quake because at least I know there's nothing wrong with my house," he said.
According to Brian Baptie, a BGS seismologist, the UK experiences about 20 earthquakes a year of a similar magnitude, the majority of which occur along the west coast.
He said: "The movements are a relic of a post-glacial uplift left over from the last ice age.
"The fault line is probably about 100m long and will have moved by about 0.5cm, so it's very minor and will not have even caused superficial damage, although people will have experienced their windows rattling.
"If we compare it to the earthquake in Japan, which had a magnitude of 9, this Blackpool quake is billions of times smaller in terms of energy.
"Only when a quake reaches a magnitude of 4 do we see any superficial damage."
An earthquake measuring 2.4 was recorded near Inverness on Tuesday with several villagers in Abriachan reporting they heard "a rumble".
The largest recorded earthquake experienced in the UK occurred in 1931 and measured 6.1.
The epicentre was Dogger Bank in the North Sea, meaning it had little impact on the mainland.
Seismologists say many of the quakes in the UK are clustered around an enormous block of rock known as the Midlands Microcraton.
This is an ancient, Precambrian (older than 590 million years) feature that runs up through Birmingham towards Stoke-on-Trent.
It is composed of harder rocks than those either side of it and scientists believe it is likely that, in response to tectonic pressures originating in the Atlantic, where the surface of the earth is being pulled apart, those softer rocks on either side are disturbed.
There are a number of active faults that line the Midlands Microcraton and many of the tremors experienced on the western side of England, up to the Pennines, are a result of rocks jostling in this area.