UPDATE – (9 a.m.) – The USGS Hawaiian Volcano Observatory reports there has been a “return to slow summit inflation”, which started last night and has “currently reached above the level that episode 54 started at, suggests that fountaining episode 55 could begin later today, September 11.”
“However, any changes in ground deformation patterns, such as deflation, or no inflation, may cause the onset to be delayed,” the USGS HVO stated.
The full HVO summit observations can be found below.
(BIVN) – Brief, precursory lava flows continue to erupt from the north vent in Halemaʻumaʻu, as the summit of Kīlauea is in an extended build to the next episode of lava fountaining.
Ground tilt remains flat. This pattern is unusual for this eruption, which began in December 2024, and has seen sharp inflation and deflation between 54 episodes of lava fountaining.
There were also several earthquakes recorded on the north end of the caldera over the last 24 hours. The quakes were all at a magnitude-2 or lower, and occurred at a depth of less than 1 km.
The USGS Volcano Alert Level for Kīlauea remains at WATCH, and the Aviation Color Code remains at ORANGE.
From the Friday morning update by the Observatory:
Summit Observations:
Weak spattering from the north vent was first reported at 6:54 p.m. HST on September 6, with the first sluggish precursory overflow from the north vent starting at around 12:45 p.m. HST on September 7. Overflows from the north vent have continued intermittently since then, with a total of 69 so far lasting from a few minutes to about 2 hours long and separated by interludes of about 15 minutes to 8 hours. Overflows between September 7-9 became progressively more vigorous and were fed by a dome fountain that reached 15-30 ft (5-10 m) tall. Two main lava flows have formed during these overflows with one making it about a half mile (1 kilometer) to the southwest of the north vent, and the other making it less than half a mile (1 kilometer) to the northeast of the north vent. On September 10, overflows were generally sluggish, less frequent, shorter in duration (less than ten minutes), not fed by a dome fountain, and did not travel as far from the north vent. Overflows this morning, September 11, have been showing more vigor and lasting longer than ten minutes. Several of the overflows this morning were fed by dome fountains15-30 ft (5-10 m) tall and generated lava flows that traveled farther from the north vent than yesterday. The most recent north vent overflow began at 7:32 a.m. HST this morning and was ongoing when this notice was published.
Webcam views at Kīlauea summit over the past day have been intermittently clear, with overnight views often obscured by weather. No overflows occurred from the south or west vents, but glow and flames were observed occasionally in all three of the eruptive vents in Halemaʻumaʻu in overnight webcam imagery.
Tremor continues across the summit with regular intervals (about 5 minutes) of gas piston activity. When webcam views have been obscured by weather, changes in tremor were used to time the duration of recent overflows from the north vent. Over the past 24 hours, 21 small earthquakes were recorded beneath the summit region. Events occurred in two general locations: 1 mile (1.5 km) below Halemaʻumaʻu or about 2 miles (3 km) deep just south of Halemaʻumaʻu. While the largest earthquake was a magnitude-2.2, most have been smaller than magnitude-2.
Summit reinflation has been very unsteady since lava fountaining episode 54 on August 25. On September 7 around 3:00 p.m. HST, inflation at UWD reached a maximum that was higher than when episode 54 began, approximately 13.2 microradians. Following this inflationary high, UWD recorded around 1 microradian of deflation with the onset of precursory lava flows from the north vent. From then on, there was little net change until around 9 p.m. HST last night, September 10, when slow inflation returned. As of this morning, UWD is slightly above the 12.7 microradians lost during episode 54.
During inter-episode pauses, the sulfur dioxide (SO2) emission rate from the summit typically varies between 1,000 and 5,000 tonnes per day. Trade winds are pushing the degassing plume to the southwest of Kīlauea’s summit caldera this morning and northerly winds later today could blow volcanic gases as well as fine ash and Pele’s hair to the south of Kaluapele if episode 55 begins.
