A loud rumbling noise was followed by houses "shaking" in parts of the Camborne and Redruth area earlier this afternoon.

People throughout the Lanner, Caharrack and Gwennap have reported feeling it, with one person saying it even reached Longdowns.

Keira Barrett contacted the Packet to say: "We just heard the weirdest noises and then our houses shook.

"It was a deep loud noise, too much for just weather - like a rumble."

She added that it had "upset and shaken up hundreds of locals."

Geothermal Engineering Limited, which is based at United Downs, subsequently put out a brief statement on its company Facebook page to say: "As part of the UDDGP testing we did cause some micro-seismicity.

"Although this was within our regulatory limits we are stopping operations until we understand the cause.

"We apologise if this has caused alarm."

Geothermal Engineering Limited (GEL) has secured funding of £10.6 million from the European Regional Development Fund to explore the geothermal resources deep beneath Cornwall.

Cornwall Council gave the company, which has offices in Falmouth, the green light back in 2010 to drill a 4.5km well at the United Downs Industrial Estate in a bid to provide renewable heat and renewable electricity.

Read next: Geothermal plant at United Downs gets green light

Drilling back in 2018 on two wells, 2.8 miles (4.5km) and 1.5 miles (2.5km) into granite, where the temperature is up to 200C (390F).

Cold water is being pumped down to the hot rocks and then brought as heated water to the surface.

The idea is that steam from the heated water will drive turbines producing electricity.

Ryan Law, managing director of GEL, said it was this process today that caused the movement.

He told the Packet: "We're just flowing water through the rock at the moment, just to understand how much power we can effectively produce.

"We always monitor this very closely in terms of what happens and we have pulled back on operations just until we fully understand what it was.

"We never want to cause alarm to people, so we try to keep people as best informed as we can.

"It is as expected and if anything it's a relatively good sign the system will perform quite well, but it is early days to indicate full results."

The so-called 'hot rocks' project is entirely separate to one being carried out by Cornish Lithium Ltd, also at United Downs, which is conducting preliminary sampling of lithium – used in batteries from electric cars to household appliances – in deep geothermal waters at the Deep Geothermal Power Project, Gwennap.

Read next: Company exploring lithium at Gwennap makes 'globally significant' breakthrough