Researchers say the cavity would once have been large enough to hold some 14 billion tonnes of ice. It is now responsible for approximately 4 percent of global sea level rise and holds enough ice to raise the world ocean a little over 2 feet.
The International Thwaites Glacier Collaboration will begin its field experiments in the Southern Hemisphere summer of 2019-20. The size and the extremely fast growth of the cavity is surprised but then they.
"We have for years suspected that Thwaites is not firmly connected to the substrate", says Co-author Eric Rignot.
Scientists spotted the concealed void thanks to a new generation of satellites, Rignot noted.
The researchers also used data from a constellation of Italian and German space-borne synthetic aperture radars. All the data was then processed using a technique called radar interferometry to show how the ground below the surface is moving between images.
Thwaites Glacier alone holds enough ice above sea level to raise sea levels by more than 65cm if it was to melt. It is thought that the water that comes from Thwaites represents up to 5% of the seal level rise that is now taking place around the earth.
This huge opening at the bottom of the Thwaites Glacier - a mass infamously dubbed the "most unsafe glacier in the world" - is so big it represents an overt chunk of the estimated 252 billion tonnes of ice Antarctica loses every year.
The Thwaites glacier is slightly smaller than the total size of the United Kingdom, approximately the same size as the state of Washington, and is located in the Amundsen Sea.
Thwaites Glacier is about the size of Florida and now responsible for roughly 4 percent of global sea rise.
NASA said the cavity is "one of several disturbing discoveries" made about the Thwaites Glacier-a 100 mile wide river of ice that is disintegrating and will one day collapse.
A study led by the agency revealed a cavity about two-thirds the area of Manhattan and roughly 304 metres tall is growing under Thwaites Glacier in West Antarctica. The glacier has been coming unstuck from a ridge in the bedrock at a steady rate of about 0.4 to 0.5 miles (0.6 to 0.8 kilometers) a year since 1992.
It's feared the melting of "the world's most unsafe glacier" could cause catastrophic flooding across the planet. In turn, this makes the glacier even more susceptible to melting. Further research revealed that the newly-discovered gap is a part of a series of patterns depict de accelerated rhythm at which ice melts in the area. The scientists have calculated that the melting glacier has already contributed to about 4 percent of the total global sea level rise.