The Monsters from Beyond Reality — V. Bertolaccini

Leading global scientists, military, archeologists, hunters, and treasure explorers uncover a fifteen-mile alien artifact, from beyond reality, after it has been buried away for millions of years on a lost desolate Pacific island, in an immense crater. A new military detection system is being tested for the first time in a plane, and the uncharted desolate Pacific island appears, and it detects something of unknown origins there, just before the equipment and plane's electronics stop working, and it crashes. They find thousands of unknown species of strange life forms, believed to be mutants, in an immense crater, at the center of the island, and enter a mind-bending lost world. They soon return to the island with hunters and start capturing them, and they explore the cavity, trying to determine what it is, and start to uncover the immense fifteen-mile alien artifact buried there - with a hideous monstrous devil-like alien entity inside - waiting to be found, and revived - with powers capable of destroying the galaxy.