(BIVN) – In the final moments of Episode 40 in the ongoing summit eruption at Kīlauea volcano, high lava fountains were reduced to spatter and flame in a matter of seconds. A video recorded by Janice Wei from a public viewing area near the Volcano House inside Hawaiʻi Volcanoes National Park captured the moment. A  crowd of onlookers cheered the finish of the event.

The nearly 10-hour event produced the kind of dramatic visuals that volcano enthusiasts have come to expect in this year-long eruption. But the events that followed that have caught the eye of scientists.

Swarms of small earthquakes are now occurring beneath the caldera. This is the first time such swarms have been detected since the eruption began in December 2024.

The latest episode was much like the previous 39 episodes. This time, only one vent was producing high fountains. Also, due to wind conditions at the summit, ash and tephra was reported to be raining down in the Uekahuna public viewing area. No injuries were reported.

The USGS Hawaiian Volcano Observatory says the episode produced 7.1 million cubic yards of lava, equal to 5.5 million cubic meters. The average effusion rate was approximately 250 cubic yards per second, the same as 190 cubic meters.

The abrupt end of Episode 40 came at just after 6 p.m. on Monday evening. After midnight, the first earthquake swarm began. It lasted for half an hour.

The second swarm occurred on Wednesday morning, with a third swarm later that evening.

All three swarms lasted about the same amount of time and have been spread out beneath east side of the crater and the south caldera. The earthquakes have been less than magnitude-2, with most being magnitude-1 or smaller. The swarms are occurring at a depth of 1 to 3 miles, or 1.5 to 5 kilometers, and are said to be volcano-tectonic earthquakes that accompany crack opening due to magmatic pressure.

Observatory scientists say it is yet to be determined if these swarms will have an impact on future lava-fountaining activity at the surface.

In an information statement, the geologists wrote:

Volcanic systems remain a complex balance of magmatic pressure and strength of the surrounding rocks. If the rocks weaken, one possible outcome is injection of a magma into a fracture creating a dike.  If the magma breaches the surface, a new vent might be created, shifting the focus of the eruption. Historically, episodic fountain eruptions can cease when the magma supply is diverted in this manner.

There is currently no observable evidence that magma is migrating away from this area. The USGS Volcano Alert Level remains at WATCH, and the next episode of high lava fountains could occur later this month, if there are no dramatic changes at the Hawaiʻi island volcano.