Mauna Loa, Hawaii's most massive volcano, may be splitting open the Earth's crust. A team of French geologists reached that conclusion after pinpointing the locations of more than 1,000 miniature earthquakes that happened beneath Mauna Loa and its little sister volcano, Kilauea, between 1988 and 1999. Some of the earthquakes under Kilauea occurred at depths well below the ocean crust, suggesting a fault there. A computer model indicates that Mauna Loa's heft was enough to bust open the crust and create that fault, says geophysicist Jean-Luc Got, of the University of Savoy in France, who led the study.
Including Mauna Loa's underwater portion and a depression it made in the seafloor, the volcano is more than 17,000 meters tall, nearly double the height of Mount Everest.