(BIVN) – The forecasted window for the start of the next episode of high lava fountains at Kīlauea volcano has arrived, although a recent switch to deflation could delay the eruption.
The eruption remains paused, for now. Small bursts of precursory spatter were recently observed overnight at the north vents within Halemaʻumaʻu crater.
“The summit recorded inflationary tilt over the past day but flattened around 4:00 a.m. HST this morning and then shifted to deflation in the past few hours,” the USGS Hawaiian Volcano Observatory reported on Saturday morning. “Current forecast models suggest that lava fountaining episode 51 is likely to start between now and July 13, but most likely today or tomorrow. However, if the current deflation is sustained, then Monday, July 13 is more likely.”
From the USGS HVO update on Saturday:
Summit Observations:
Strong glow was visible from the north vent overnight, with nearly continuous spatter starting around midnight. The north vent spattering has become less vigorous this morning following the start of slow summit deflation. The accumulation of spatter landing around the north vent rim has built up a small cone around the vent. Glow from the south vent was dim most of the night but was punctuated by periods of bright glow after 3:00 a.m. HST. The bright glow correlated with spikes in tremor and appears to mark the onset of gas piston activity in the south vent. One of these periods produced visible spatter early this morning.
Continuous, low-level seismic tremor transitioned to cyclic tremor bursts every 5-10 minutes around 3:00 a.m. HST. These spikes appear to mark drainback events associated with gas piston cycles in the south vent. Earthquake activity beneath Kaluapele (Kīlauea caldera) remains low.
Kīlauea summit has recorded inflationary tilt over much of the past few days, however, starting around 4:00 a.m. HST this morning the tilt flattened followed by slight deflation over the past few hours. Several deflationary trends have interrupted the overall inflationary pattern following episode 50, and the current deflation may push back the eruption forecast window if it continues. Tilt recovery since the end of episode 50 presently stands at about 15.3 microradians on the Uēkahuna (UWD) tiltmeter, an increase of 1.2 microradians since yesterday morning. Summit deflation totaled 15.3 microradians on UWD during episode 50.
The sulfur dioxide (SO2) emission rate from the summit is likely now varying within a typical range of 1,000 to 5,000 tonnes per day.
Rift Zone Observations:
Rates of seismicity and ground deformation remain low in the East Rift Zone and Southwest Rift Zone. SO2 emissions from the East Rift Zone remain below the detection limit.
Analysis:
Summit reinflation continued over most of the past few days but has flattened early this morning and is now slightly deflating, which may push back the forecast window for episode 51. Vent glow has been continuous since the end of episode 50. Strong glow and nearly continuous spatter from the north vent along with variable glow from the south vent overnight, indicates that magma is very near the surface. The current forecast suggests that episode 51 will occur sometime between now and July 13, most likely today or tomorrow if the current deflationary tilt is short lived.
Kīlauea has been erupting episodically since December 23, 2024, from two vents (north and south) in Halema‘uma‘u. Lava fountaining episodes, which generally last for less than 12 hours, are separated by pauses that can be longer than three weeks.
