The Benham Rise is an oceanic large igneous province at the western margin of the Philippine Sea. It has an ocean island basalt geochemistry, a surface area of 0.11 Mkm2 and a volume of ~0.13 Mkm3. A crustal thickness of ~15 km is estimated from gravity anomalies. Volcanism was most active in the early stages of its formation, during the Lutetian from ~47.9 Ma to 41.3 Ma, although volcanic activity extended to ~26 Ma.

Multibeam bathymetry with almost 100% coverage has revealed the morphology of Benham Rise for the first time. It consists of a main body (~310 km by 330 km) with the Narra, Loro and Molave Spurs extending 100–200 km from its eastern side. The main body is built on a shield platform from ~5200 m to ~3800 m sub-sea. The platform flanks consist of ~3–15 km wide terraces with scarps as high as 100 m to 300 m. The platform is surmounted by a crest exhibiting caldera morphology at an average depth of ~2500 m. The crest is named Apolaki Caldera and may be the world's largest known caldera with a diameter of ~150 km. Features like a breached rim, intra-caldera benches, and a resurgent dome indicate a multi-phase volcanic history consisting of both quiet and explosive eruptions.

The bathymetry and publicly available geological and geophysical data record three main stages in the tectonic history of Benham Rise – shield-building, caldera formation, and post-caldera/late stage volcanism. The platform base is interpreted to have formed over a hotspot beneath the Central Basin Spreading Center during the shield-building phase between ~47.9 Ma to ~42.5 Ma. The arrowhead shaped Molave Spur is interpreted to have formed late in this stage along a ridge that propagated away from the hotspot. The caldera formation followed and is interpreted to have occurred before ~41.3–41.5 Ma when Benham Rise was still joined with Urdaneta Plateau. The Narra Spur was formed by late-stage hotspot related volcanism, as Benham Rise and Urdaneta Plateau separated, and ended with the eruptions of the Vinogradov Seamount at ~26 Ma.