A 4.2 magnitude earthquake has been recorded in Kent, the British Geological Survey (BGS) has said.
The tremor originated near Sandwich at a depth of 13km (8 miles) at 02:52 BST, it reported.
Residents in areas including Margate, Canterbury and Southend-on-Sea in Essex felt the tremor, with some saying they thought it was a plane crash or a bomb.
Kent Police said a number of calls had been received but no injuries or structural damage had been reported.
But Herbert Smith tweeted that he and his wife Doreen were taking refuge in their caravan after being evacuated from their damaged home in Flete.
The European-Mediterranean Seismological Centre (EMSC), which monitors seismic activity across the continent, also recorded the earthquake.
Theresa Foord, from Eastry near Sandwich, said: "I heard this massive crash and then the whole house started to shake.
"Plates came off the wall, doors came open - it was all very frightening.
"It seemed to go on for ages but it was about three to five seconds."
Kent earthquake 260,000 times smaller than Nepal
About 200 earthquakes take place in the UK every year but not all are as large as this tremor, according to BGS seismologist David Galloway.
"We probably get one of this size once every three or four years so it is quite significant for people if their houses are shaking or they are woken from sleep," he said.
"But in world terms, it was about 260,000 times smaller than the earthquake in Nepal.
"In the UK the biggest earthquake happened in 1931 off East Anglia at Dogger Bank. That had the magnitude 6.1."
BBC South East reporter Simon Jones, who lives in Canterbury, said he was woken up when his house started shaking.
"The initial thought was perhaps something had gone into the house, like a lorry but then I turned to social media and people right across east Kent were reporting an earthquake," he said.
Vikki Petts tweeted: "So we just had a 4.3 magnitude earthquake in Kent and my housemates slept through the entire thing. certainly woke me up!"
Caroline Knott, from Ramsgate, said the earthquake woke her up, adding "I thought maybe a bomb's gone off".
Jonathan Tapp said: "Earthquake in East Kent and now can't get back to sleep. Despite months spent in [New Zealand] this is my first one that I've felt."
Iain Buchanan, from Ramsgate, said: "So I'm not going mental, my house shook due to an earthquake in Kent of all places."
Police said they began receiving reports of the tremor in east Kent at about 02:57 BST.
Neither the force nor Kent Fire and Rescue Services had received any reports of structural damage or injuries, they said.
Hundreds of homes in Folkestone were damaged by a 4.3 magnitude tremor which struck parts of Kent in 2007.
More than 70 buildings were so dangerous residents could not return to them because of loose chimney stacks, tiles and masonry.