The Tamu Massif was formed about 145 million years ago during the Late
Jurassic to Early
Cretaceous period would make the Tamu Massif the largest known volcano on
Earth, dwarfing the current record-holder,
Pūhāhonu, in the
Hawaiian Islands. The main part of Tamu's rounded dome extends over an area of , totaling more than , many times larger than Mauna Loa, which has an area of , and about half the area of the
Martian volcano
Olympus Mons. The entire mass of Tamu consists of
basalt. Its
slopes are very gradual, ranging from less than half a degree to one degree near its summit. The Shatsky Rise oceanic plateau is comparable in size to
California or
Japan, or
Britain and
Ireland together. 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 study found that the
Moho line, the boundary between the Earth's crust and mantle, extends more than beneath the base of Tamu Massif, meaning that the volcano is unlikely to ever erupt again, since magma is presumably unable to penetrate a barrier that thick. ==See also==