Using magnetic lineations, researchers discovered that there are three bathymetric highs and a low ridge, a topography that would imply three separate volcanoes; but the plume-head model indicates a single massive volcano. Based on multichannel seismic profiles and rock samples from Integrated Ocean Drilling Program (IODP) core sites, Tamu Massif appears to be a single massive volcano made of lava flows that emanated from the volcano centre and formed its shield shape; however, the profiles have large gaps in them, leaving open the possibility that it may represent the activity of more than one volcano. A subsequent study in 2016 found that the massif was likely generated by a single volcano. In 2015, researchers found that the volcano's structure bore patterns of magnetic striping on either side, indicating that the volcano is likely a hybrid of a mid-ocean ridge and a shield volcano. Geologic data also indicated that Tamu Massif formed at the junction of three mid-ocean ridges, which was a highly unusual occurrence.