The lava supply onto the Halemaʻumaʻu lava lake has ceased.
The growing lava lake stopped being fed by lava around 11:15 local time in the morning of 16 September. The HVO volcanologists reported that the active lava flow is restricted only to a ponded area north of vents on the downdropped block.
Webcam views showed the ponded lava to be inactive by around noon. Overnight views depicted incandescence across the eruptive fissure, hinting cooling, i.e. crystallization of lava.
The volcanic tremor (an indicator of moving magma towards the surface) decreased to pre-eruption levels at 17:00 local time on 16 September.
Sulfur dioxide (SO2) emissions declined to pre-eruptive levels as well, with only 800 tonnes on 16 September.
Thus, the Hawaiian Volcano Observatory lowered the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory.
Source: Hawaiian Volcano Observatory volcano activity update 18 September 2023