It sounded like a large lorry rumbling by – but it was the second earthquake in a fornight in the north of England.
But these things don't usually come in threes, the British Geological Survey in Edinburgh, has assured the nation.
"They are random events," said seismologist Brian Baptie, "and a quake of this magnitude (3.5 on the Richter scale) usually happens once a year.
"This was only a small tremor and shouldn't have caused any structural damage. We might expect windows to rattle or small objects to fall over but it shouldn't damage house foundations.
"Fortunately, we live in a pretty benign part of the planet and should never get the quakes seen in places like Indonesia, Japan or California.
"These places lie at the boundaries of tectonic plates which move about
and give off a lot of energy. But Britain lies in the middle of a plate."
The latest quake had its epicentre around the village of Kirkby Malzeard, about five miles north-west of Ripon. The British Geological Survey estimated its effects might be felt within a 60-mile radius, as far away as Barrow-in-Furness or Newcastle-on-Tyne.
Certainly, it registered in parts of Leeds and North Yorkshire, according to our readers.
At Princes Villa Road, Harrogate, Gilly Delon and her husband Dion, who run Frog Water Services, were sitting on separate sofas when the quake struck.
"My settee shook and the curtain behind me moved," said Gilly. "I
jumped up thinking it was a poltergeist! But my husband thought immediately it was a earthquake. He said it was like a train going through a tunnel beneath the house.
"A friend of mine at Starbeck said her dogs were growling and acting strangely."
Philip Baldwin and his wife Vivienne were watching TV in the village of Burton Leonard near Ripon when they heard a terrific thud – "like a large piece of furniture falling over upstairs."
"The house actually shook for a few seconds," said Mr Baldwin. "We
wondered if our boiler had exploded. I went outside to check if the chimney had collapsed through the roof and other neighbours had also gone outside.
"I thought the noise might have been an aircraft because we get military aircraft flying over here. Then I heard on the news it had been an earthquake.
"I experienced one in Bradford about 20 years ago but it wasn't as noisy as this one."
Ruth Simpson, of Glebe Court, Rothwell, was in her kitchen when she felt the room shudder. "It was a bit unnerving because it's the unknown," she said. "But my husband Steve didn't feel a thing."
Libby Whitehead, 23, of Bramley, thought her daughter Eloise had jumped out of bed and had run across the bedroom floor. "We didn't think anything about it," she said, "and then I went onto Facebook and saw friends talking about an earthquake."
Vicky Carr, 27, of Oakwood, Leeds, thought a bus had gone past her house making a lot of noise; and Amy Craven, 33, of Greenfield Road, Harrogate, said she thought a lorry had rumbled down her street.
"There was a strong vibration and a few things shook," she said.
There are said to be 200-300 quakes in Britain every year but most are so small that no one notices them. The first in recorded history happened way back in 974AD and there were four in the 11th century.
The biggest ever recorded, measuring 6.1, occurred in 1941 in the North Sea off Great Yarmouth.
A tremor measuring 4.8 was registered at Skipton in 1944 and a 5.1 quake in the North Sea in 1958 was felt throughout eastern England.
In February 2008, a large tremor (5.2) at Market Rasen, Lincs, was felt across Yorkshire and as far away as Brighton and Wales.