An underwater landslide is thought to have caused a small tsunami that sent holidaymakers and anglers scattering in Cornwall. Witnesses reported the sea being sucked out, or receding, before a wave struck the coast on Monday morning.

No damage was caused by the wave, thought to have been about 40cm (16in) high and causing a surge up to 90cm (3ft) by the time the seawater pushed into the Yealm estuary, 70 miles up the coast near Plymouth, Devon, but many people, along the south coast, up to Hampshire, were left baffled by the phenomenon.

There were reports that static electricity in the air at the time made people's hair stand on end.

Simon Evans, who was digging for bait on the shore at Marazion, near Penzance, described the event as akin to a horror film. He said: "It was really eerie ... the weather was really foggy but extremely warm and close, and the sea was as calm as a millpond.

"One minute I was stood at the water's edge then when I turned around the water had retreated around 50 yards.

"It was surreal, I couldn't believe what had happened. I had no idea what caused it, but I didn't really want to hang about and find out."

He said that having heard about tsunamis, he "jumped in the car and got out of there".

Experts attributed the tsunami to a submarine landslide perhaps a couple of hundred miles out to sea.

According to the Tidal Gauge Anomaly measure, which records the difference between the forecast tide and actual tide, the wave was higher by 20cm in Newlyn, 30cm in Plymouth and 40cm in Portsmouth.

Bob Hunt, the head guide for St Michael's Mount in Cornwall, said day-trippers were caught out as they walked across the causeway to the island.

"One minute they were happily walking across the walkway, the next they were knee-deep in water. It was bizarre.

"Ordinarily, the water slowly trickles across the walkway and the tide comes in over a matter of hours but it happened in a flash."

There was also a feeling of lots of static in the air. "People's hair suddenly stood on end," Hunt said.

Further east, at the border of Cornwall and Devon, sailor Roland Stuart said his vessel was rocked by the wave.

"My boat was moving around with the speed of the water rushing in. I wondered what the hell was going on. All sorts of things crossed my mind. Within 15 minutes it was all over."

Film footage taken by one witness showed the tsunami moving up the river Yealm against the natural tidal flow.

Bob Brown was launching his dinghy at the mouth of the estuary at about 10.30am on Monday.

He said: "The tide was coming in from left to right. All of a sudden it stopped coming in from the sea and went back the other way. It came back at quite a force, all the boats were bobbing around.

"To see a tide suddenly stop and go back the other way at four times the speed was unbelievable."

Mark Davidson, associate professor in coastal processes at the University of Plymouth, said people had reported seeing the sea being "sucked out" before a series of waves charged in.

He believed it was a tsunami, probably caused not by an earthquake but by a landslide out at sea.

Such a landslide might have occurred at a place where the seabed sloped steeply down, such as at the edge of the continental shelf, about 250 miles off Land's End.

However, had it taken place there, Davidson said, the tsunami probably would have been reported elsewhere, not just along the south coast.