This USGS video shows “cyclic fluctuations” in eruptive vigor that were present Jan. 22-23, 2021, at the western fissure in Halema‘uma‘u crater at the summit of Kilauea volcano. The cycles lasted 5-6 minutes.
Peaks in the cycles resulted in high flow rates in the channel and spattering at the vents. During troughs in the cycles, the fissure became nearly inactive. These variations may be due to oscillations in the height of the lava column in the vent, according to USGS. The video is shown at 90X speed.