https://www.vice.com/en_us/article/m7jng4/a-mysterious-crater-suddenly-opened-up-in-the-arctic-tundra

Siberian media reported the discovery of a 50-meter deep crater in the Arctic tundra that suddenly opened up. Craters like these have been found since 2014, and scientists believe they may be a result of cryogenic eruptions—in other words, ice volcanoes. 

According to the Siberian Times, a TV crew from station Vesti Yamal observed the massive crater by chance while traveling from an assignment. The crater is one of several on the Yamal and Taymyr peninsulas in Siberia, and these geological phenomena have been subjects of research for years.