Satellite images confirm that there is a persistent lava lake in the crater of a remote volcano in the British Overseas Territory (BOT).
Only a few permanent lava lakes are known worldwide. The Mount Michael on Saunders Island in the South Atlantic is perhaps only the eighth example of this kind.
The 990 m high position of the Stratovolcan makes climbing extremely difficult.
Space images are therefore actually the only way to look into the opening of the summit.
Circulating sensors have already discovered thermal anomalies in the crater in the 1990s.
In order to dissolve the crater floor and check the presence, most modern satellites were required of the lake.
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Scientists from University College London (UCL) and the British Antarctic Survey (BAS) evaluated data from 2003 to 2018.  This information indicates a continuous lava melt, which is between 90 m and 215 m wide and has a temperature of about 1000 ° C.
There are about 1,500 active volcanoes on the earth's surface, but it is extremely rare for them to hold a seething mass of liquid in their craters.
Saunders Island is part of the British Overseas Territory of South Georgia and South Sandwich Islands.
"The island has been visited many times, but nobody has ever climbed the mountain," commented Dr. Peter Fretwell of BAS.
"If you look at the pictures, you can see why: The summit is surrounded by a huge snow mushroom, extremely soft snow with a sugar-like texture, probably caused by the constant release of steam through the volcano. " Man can not get over it, you'd have to dig it, but it would be dangerous to spend your time on such an active volcano, "he told BBC News.
" Without high-resolution satellite images, it would be dangerous. "It would be extremely difficult have been to learn more about this amazing geological feature, "added Danielle Gray of UCL.
One key question is how Mount Michael can entertain the lake. Why does not it solidify from time to time?
BAS colleague dr. Alex Burton-Johnson said it had been a mystery for a long time.
"We understand that volcanoes emit two kinds of material: rocks (in the form of lava, pumice and volcanic ash) and what we call volatile substances (hot gases, including water, carbon dioxide and sulfur dioxide), hence the white ones Clouds (the water) and smell (the sulfur), "he told BBC News.
" Both are incredibly hot and transmit heat from the depths of the mantle. For most volcanoes, the rock outcrops lead to lava flows, but for a lava lake to remain molten, but not overflow, the lava flow from the depth must be low, and instead, most of the ejected matter and the source of heat must be from the gases.
"This implies that the lava under the volcano is very rich in gas."
This demand for a constant flow of heat only from the expelled gases could explain why there is always a cloud of vapor emissions to be seen in the volcano. Burton Johnson. This was already established in 1820 by the Russian explorer Fabian Gottlieb von Bellingshausen.
"By contrast, observations of eruption activity are rare," added the geologist.
The UCL / BAS team reports on its assessment of Mount Michael lava lake in the Volcanology and Geothermal Research journal.
Lava lakes are also known at the Nyiragongo volcano in the DR Congo. Erta Ale volcano, Ethiopia; Mount Erebus, Antarctica; Mount Yasur, Vanuatu; Ambrym volcanic island, Vanuatu; Kilauea, Hawaii; and volcano Masaya, Nicaragua.