Godzilla seafloor formation gains global geological heritage status
The underwater formation near Okinotorishima is believed to be the largest megamullion discovered, measuring about 125 kilometers long.
An underwater formation discovered in 2001 during a Japan Coast Guard continental shelf survey has gained international geological recognition, the agency said. The Godzilla Megamullion was selected for the International Union of Geological Sciences’ list of 100 Geological Heritage Sites.
The formation lies on the Philippine Sea plate, southeast of Okinotorishima, a remote Pacific island administered by Tokyo. It measures about 125 kilometers long and 55 kilometers wide—roughly 10 times the size of a typical megamullion—and is believed to be the largest ever discovered.
Megamullions are dome-shaped structures created when faulting linked to the spreading of the seafloor exposes mantle rocks. An international research team led by Japanese scientists has studied the Godzilla formation, producing findings about mantle structure and how plates form. The Coast Guard said the designation recognizes its global importance as a reference site for geological research.
Its size inspired the name Godzilla, which received international registration in 2021. The selection came in the IUGS list’s third round. Earlier Japanese entries include Hyogo Prefecture’s Nojima Fault, which triggered the 1995 Great Hanshin Earthquake.
