(BIVN) – Lava fountains burst from the vents atop Kīlauea volcano on Mothers Day, marking the 21st episode in the ongoing summit eruption on the Hawaiʻi island.

In the early afternoon, fountains over 500 feet high – or 150 meters – shot into the sky in a fan-like pattern, feeding large lava-flows that travelled across the crater floor.

Scientists had anticipated Episode 21 would begin at around this time, based on the rates of inflation at the summit.

The first signs of renewed lava activity flickered into view overnight, when prominent flames and intermittent spatter could be seen at the north vent after 7 p.m. The USGS Hawaiian Volcano Observatory says these yellowish flames are due to the burning of hydrogen gas.

Gas-pistoning and occasional low-level dome fountaining could be seen early Sunday, until fountains increased at 12:45 p.m.

USGS webcam view of the sustained lava fountains on Sunday during Episode 21

Scientists report this phase of activity was accompanied by a rapid change in summit tilt from inflation to deflation, along with a rapid increase in volcanic tremor.  

Strong degassing is also occurring with the vigorous lava fountaining, releasing an estimated 50,000 tonnes of Sulphur Dioxide per day. The observatory noted winds are from the northeast, blowing the plume to the southwest, and away from the main viewing areas and communities. 

This phase of the episode is not expected to last long, and the next pause in the summit eruption is expected to begin in short order. 

The USGS Volcano Alert level for Kilauea remains at WATCH.