A rare lake of sizzling molten lava has been discovered atop a volcano near Antarctica.
The permanent bubbling pool of molten rock was found at the centre of Mt Michael, a 700m-high peak on Saunders Island in the South Sandwich Islands group east of Argentina.
It's only the eighth such lake of its type ever discovered, volcanologists said.
It's possibly more than 200m across, and between 989C and 1279C.
"Despite lava lakes being extremely rare with only a few global examples, previous analyses of satellite imagery of Mt Michael in the 1990s showed persistent thermal anomalies not associated with magma overflowing the crater," the study, published in the Journal of Volcanology and Geothermal Research, said.
"This suggested the existence of a lava lake inside Mt Michael's crater. However, their study relied on 1 km resolution imagery, and there have been no long-term investigations to determine if this is a persistent feature."
Being so remote - in the Southern Ocean about halfway between South America and Africa, and not far from Antarctica - few scientists have ever been there.
"It is extremely difficult to access, and without high-resolution satellite imagery it would have been very challenging to learn more about this amazing geological feature," said lead author Danielle Gray from University College London.
New, higher-resolution satellite imagery revealed the lava lake.
Mt Erebus in Antarctica, the site of New Zealand aviation's worst-ever disaster in 1979, is one of the other seven peaks with a permanent lava lake. The others are Nyiragongo Volcano, DR Congo; Erta Ale Volcano, Ethiopia; Mt Yasur Vanuatu; Kilauea, Hawaii and Ambrym, Vanuatu; and Masaya, Nicaragua.
"Identifying the lava lake has improved our understanding of the volcanic activity and hazard on this remote island, and tells us more about these rare features, and finally, it has helped us develop techniques to monitor volcanoes from space," said author and geologist Dr Alex Burton-Johnson of the British Antarctic Survey.
- Aucklanders should get ready for an eruption - expert
- Newshub graphic reveals Auckland's deadly volcanic field
- Auckland volcanic eruption: Rubble, ruin and refugees