lava flows from mauna kea overlapped in complex layers with those of its neighbors during its growth. most prominently, mauna kea is built upon older flows from kohala to the northwest, and intersects the base of mauna loa to the south. the original eruptive fissures (rift zones) in the flanks of mauna kea were buried by its post-shield volcanism. hilo ridge, a prominent underwater rift zone structure east of mauna kea, was once believed to be a part of the volcano; however, it is now understood to be a rift zone of kohala that has been affected by younger mauna kea flows.