(BIVN) – Precursory lava activity is underway at the Kīlauea summit vents, as the Hawaiʻi island volcano builds to episode 42 in the ongoing eruption within Hawaiʻi Volcanoes National Park. 

High lava fountains are expected to occur today (Sunday, February 15) or tomorrow (Monday, February 16), the USGS Hawaiian Volcano Observatory says. 

Precursory dome fountaining occurred Saturday night at the north vent in Halemaʻumaʻu, sending lava onto the crater floor. Lava spattering was also observed at the south vent. 

The Observatory noted one of its webcams, V3, is experiencing data issues and will be replaced following episode 42. 

USGS webcam view shows lava at the summit of Kīlauea on Sunday morning

From the USGS HVO update issued Sunday morning:

Summit Observations:

Both the north and south vents were active in the past 24 hours. Small precursory overflows from the north vent occurred at 1:05-1:06 pm, 4:41-4:50 pm, and 5:56-6:05 pm HST yesterday. The south vent produced two small overflows at 3:51-3:52 am and 4:06-4:08 am HST this morning. Spattering was visible from both vents all night and continues this morning, which indicates that lava is at the surface just below the edges of the vents.

Seismic tremor continued over the past 24 hours and has been relatively steady over the past day. The overflows from the north vent yesterday created slight tremor lulls followed by peaks during drainback. There were 10 small earthquakes located across the summit region during the past day with only one greater than magnitude one.

The Uēkahuna tiltmeter (UWD) recorded steady inflation from 9:30 am HST yesterday until about 4:15 am HST today, and peaked at 31 microradians of inflation. This is equal to the episode 41 deflation. Since 4:15 am HST today, shortly after the south vent overflows, the summit deflated about 0.2 microradians, though that has been mostly recovered at this time. Shorter periods of no inflation also correlated with the north vent overflows yesterday.

In recent days, the sulfur dioxide (SO2) emission rate from the summit has varied within the typical range of 1,000 to 5,000 tonnes of SO2 per day, as has been observed during previous eruptive pauses. This is considerably lower than rates observed during lava fountaining episodes. This morning, webcams show that the plume from the summit vents is being carried to the southwest. The National Weather Service forecast for the Kīlauea summit region for today indicates winds from the northeast at 13 to 17 mph, with gusts as high as 24 mph, and increasing tonight to 18 to 22 mph and gusts to 31 mph.

Rift Zone Observations:

Rates of seismicity and ground deformation remain very low in the East Rift Zone and Southwest Rift Zone. SO2 emissions from the East Rift Zone remain below the detection limit.

Analysis:

The rapid rebound of inflationary tilt, glow from the vents, and presence of low-level volcanic tremor after episode 41 indicate that another lava fountaining episode is likely. Spattering and overflows from both vents overnight indicates that magma remains high in the column. Summit inflation as recorded by the Uēkahuna tiltmeter equaled the tilt loss during episode 41. There was a slight deflation beginning at 4:15 am HST, indicating that the summit continues to alternate between inflation and deflation. Models indicate the current forecast window for the start of episode 42 fountaining is today or tomorrow February 15 to 16, but the start is more likely to happen during a period of inflation. The combination of the alternating inflation and deflation over the past few days and the increase in summit earthquakes may indicate that it is getting progressively more difficult to generate the pressure needed to trigger fountain episodes.

Kīlauea has been erupting episodically since December 23, 2024, primarily from two vents (north and south) in Halema‘uma‘u. Eruptive episodes, which generally last for less than 12 hours, are separated by pauses that can be as long as over two weeks.

HVO continues to closely monitor Kīlauea and is in contact with Hawai‘i Volcanoes National Park and the Hawai‘i County Civil Defense Agency about eruptive hazards.