In an extremely rare scientific collaboration between North Korea, U.S. and U.K., researchers discovered that Mt. Paektu, one of the three "spirited" mountains of Koreans, has a soft spot in its core.

According to their press release, researchers found significant amounts of melted materials in the crust beneath the volcano, which extends laterally to at least 20 kilometers, making up a complex magma reservoir. Researchers suggest that the soft crust was the result of the modification made by magmatism associated to with volcanism.

For the study, published in the journal Science Advances, researchers used the data from six broadband seismic stations that was provided by the National Environment Research Council (NERC) UK instrument pool SEIS-UK in 2013.

Seismic waves from distant earthquakes rippling through the crust beneath the volcano were recorded by the researchers over the course of two years. Researchers found alterations in the wave energy and form, which suggest a softer, presumably molten rock. These findings, according to the team, explain the swarm of earthquakes recorded at the volcano between 2002 and 2005.

Mt. Paektu, or Changbai Mountain for the Chinese, is a volcano that can be found in the border between North Korea and China. Its crater houses a lake called Chon, which is considered to be the deepest crater lakes in the world and is also in the list of the coldest crate lake, according to Korea Konsult.

The volcano was also celebrated by Koreans as a sacred mountain. It's the place of their ancestral origin and the heart of Korean revolution. Mt. Paektu is also believed to be the birthplace of North Korean's "Dear Leader," Kim Jong II.

The last recorded eruption of Mt. Paektu was in 1903, but in 946 C.E., the volcano unleashed one of the biggest eruption in human history that covered the whole of East Asia with volcanic ash.