Erangel is a fictional island in the black sea abandoned near Russia where a military occupation was controlling it. The military occupation tested chemical/biological experiments on the local populace. After a resistance attack on a biological facility, the island had to be abandoned.
Erangel was originally occupied by Soviet forces from the 1950s onwards and was used as a military testing facility, which explains the military base as well as the hospital and storage facilities. A local resistance movement fought to reclaim the island which eventually lead to the island becoming abandoned. The electrical field seen wreaking havoc on the island is powered by electrical emitters which were used to contain towns that were showing signs of revolting against the Soviet forces.