Natural Disaster. An undersea mountain range extending through the North and South Atlantic Oceans, the Indian Ocean, and the South Pacific Ocean, and consists of many small and slightly offset segments. Each segment is characterized by a central rift where two tectonic plates are being pulled apart and new oceanic lithosphere is being created. See Uyeda (2002), Cox (1973), Uyeda (1978), Duff (1993), and Hancock and Skinner (2000)