An area near the Podkamennaya Tunguska River in the Easter Siberian Taiga which experienced a massive explosion on June 30, 1908, that flattened an estimated 80 million trees over an area of 830 square miles of forest; its cause is still under debate to this day.

From the Ra Contact: The site of where, in 1908, the Confederation detonated a malfunctioning drone designed to assess humanity’s progress in the technical sphere. The region was chosen because of its remoteness and the unlikelihood of harming any third-density entities.

Reference

17.3–7