(BIVN) – The ongoing eruption at the summit of Kīlauea remains paused, and the projected start of the next episode of lava fountaining at Hawaiʻi Volcanoes National Park has been delayed. 

“Overnight significant deflation was recorded across the summit of Kīlauea and models now show that episode 31 fountains are likely to start between August 22 and August 25,” the USGS Hawaiian Volcano Observatory wrote on Wednesday. “Moderate glow and sustained tremor indicate that magma remains at relatively shallow depths beneath the active vents.” 

“Tilt was down by about 1 microradian overnight at UWD and 0.4 microradians at SDH, similar to decreases recorded several days prior to episode 30 fountaining episode,” the Observatory reported. “Overnight there was continuous tremor punctuated by bursts.” 

USGS: “On August 18, two USGS scientists and two researchers from the University of Colorado hiked to an overview of the north vent in Halemaʻumaʻu crater at Kīlauea volcano. The goal of the observation was to confirm if lava was moving up inside the vent. While perched lava was not observed, lava spatter was visible intermittently during gas pistoning events.”

From the USGS HVO analysis provided on Wednesday:

Beginning in the afternoon on August 18, deflation was recorded on both the UWD and SDH tiltmeters indicating summit wide deflation that has continued over the past 24 hours. Prior inflation rates were about 1 microradian a day which is normal for this part of the repose period. Similar deflation preceded episode 30 and appear to be related to variation in supply rate as there is no indication of any significant movement of magma from the summit region. Models now show the possible onset of episode 31 fountains to likely be between August 22 and August 25 if inflation resumes today and continues. If increasing vent elevation (see below) is factored into the model the likely window for the onset of fountaining is August 23 to August 26. Any changes in inflation rate will affect the models. Periods of no inflation or deflation, as seen prior to episode 30, cannot be forecast and will delay the onset of the next episode.

NOTE: The V3 camera is currently in Black and White Infrared Mode at night and is much more sensitive to heat and light than the V1 camera at this time.

The injection of a shallow dike resulted in the new southern fissure vent at the onset of episode 30. Dike emplacement in the south caldera suggested that eruptive pressure continued to increase as the vent elevation got higher and magma was injected into weak areas of the surrounding summit. It is possible this could result in permanent change in the vent locations and eruptive behavior. Currently, there are no indications that any eruptive activity would occur outside of the summit region. Kīlaueaʻs East Rift Zone continues to contract, indicating no magma is entering that part of the system.

The current eruption has been characterized by episodic lava fountaining not seen in any eruptions since the 1983–86 episodic fountains at the beginning of the Puʻuʻōʻō eruption. Lava fountains and flows have erupted from two vents within Halemaʻumaʻu crater that we refer to as the north vent and south vent. Each of the previous fountaining episodes lasted from a few hours to over a week and was accompanied by strong deflation of the summit region. Pauses between the fountaining episodes have been marked by an immediate switch from deflation to inflation as the magma chamber recharges and repressurizes. Fountaining episodes have occurred approximately once per week since the start of the current eruption on December 23, 2024.

The USGS Volcano Alert level for Kīlauea remains at WATCH.