An earthquake measuring 3.6 on the Richter scale has been felt in parts of Herefordshire and Worcestershire.
The British Geological Survey (BGS) described the quake at 1806 GMT as weak, with its epicentre 6km (3.7 miles) from Bromyard.
Sandra Green, in Tenbury Wells, Worcestershire, told the BBC she felt a "thud through the whole house".
People further away in the West Midlands also reported a tremor. The BGS is monitoring for aftershocks.
Seismologist David Galloway said: "It's really a case of wait and see."
"People have described it as a lorry crashing in to the side of their house and on analysis of our instruments there has been an earthquake of 3.6 on the Richter Scale," he said.
"We record about 200 earthquakes a year but most go unnoticed by the general public. One or two a month are felt and this was quite widely felt."
Heather Blevins, 43, of Belmont, Herefordshire, said "the whole house shook" but nothing was damaged.
Cerianne Thorneycroft, of Lower Bullingham, also in Herefordshire, said she thought the rumble was a heavy train on the railway track, before realising the whole house had been shaken.
A resident in Great Witley, Worcestershire, said she heard a "low booming noise and the whole house shook".
Others living near the epicentre contacted the BBC to report walls creaking, furniture shifting and houses shuddering, but so far there have been no reports of damage or injuries.
Police said they received reports of it affecting an area between Malvern and Worcester but a report also came in from Dudley, 74km (46 miles) away from Bromyard.
Mr Galloway said: "The cause of the earthquake is that we live on a dynamic planet and these plates are moving all over the world and this creates stress in the rocks.
"We are in the middle of one of these plates so we don't get the earthquakes like they do in Japan or Turkey."