magma in a shallow reservoir beneath the summit drains into the East R
magma in a shallow reservoir beneath the summit drains into the East RAs magma in a shallow reservoir beneath the summit drains into the East Rift Zone, the ground above it sags, cracks and subsides. The Halema‘uma‘u crater has dropped about 400 m (1300 ft) between early May and late June. Inward slumping of the surrounding Kīlauea Crater floor has doubled the diameter of Halema‘uma‘u.