Inaya Alexander

The platform's 150-200m-thick structure had started to split, with one particular crack - dubbed Chasm One - propagating at a steady pace after decades of dormancy.

This fissure eventually cut through the entire shelf. It was the movement on a spring tide that appeared to provide the final impetus.

Although Halley is sited a good 20km (12 miles) back from the line of rupture, sensors on the ice immediately reported a sudden shift in position.

Subsequent satellite imagery has revealed A81 is about 1,550 sq km - nearly as big as of Greater London and marginally bigger than A74, which calved to the east of Halley in February 2021.

You definitely shouldn't panic but there is a biggish asteroid about to pass by Earth in the coming hours.

About the size of a bus, the space rock, known as 2023 BU, will whip over the southern tip of South America just after midnight GMT.

With a closest expected approach of 3,600km (2,200 miles), it counts as a close shave.

Ms Stevenson, who co-founded Beach Guardian, was in Sennen, hosting a group clearing plastic from the dunes when she found the remains of a skull.

She said: "There have been times before, when I'm exploring hidden coves, or deep, dark caves filled with plastic, that I have worried about finding human remains. But it really wasn't expected on a popular beach like this."

Nothing on that scale looks like it is about to happen under the area studied by Upflow, fortunately. But it's thought still to be an excellent laboratory.

Its siting was close to the Mid-Atlantic Ridge where some of Earth's tectonic plates meet. The nearby continent of Africa would also influence how plumes would flow. The Upflow team hopes to publish its imagery in the next couple of years.

The project is funded by the European Research Council. Co-principal investigator is Prof Miguel Miranda from the Portuguese Institute for Sea and Atmosphere (IPMA).