What makes the lava lake within Halema‘uma‘u rise and fall?

On January 8, 2018, Kīlauea Volcano's summit lava lake level was 38 m (125 ft) below the rim of "Overlook crater," the small crater that formed above the active vent in Halema‘uma‘u. The lava lake continuously emits elevated levels of sulfur dioxide gas and erupts small, but measurable, amounts of Pele's hair and other ash-sized tephra (airborne lava fragments) that accumulate on the rim of Halema‘uma‘u (lower right) and areas downwind of the lake. USGS photo by J. Sutton.