(BIVN) – The ongoing eruption at the summit of Kīlauea remains paused. Geologists say periods of weak deflation or no inflation, uncommon for the early stages of repose between lava fountaining events, are interrupting the build to episode 43. 

On Monday, the USGS Hawaiian Volcano Observatory pushed back the forecast window for the onset of episode 43 to March 6th through March 16th. 

“Another period of weak deflation began yesterday afternoon and continues this morning,” wrote the Observatory in a morning update. “The UWD tiltmeter has recorded a total recovery of nearly 13.4 microradians of inflationary tilt since the end of episode 42, with a loss of about 0.6 microradians over the past 24 hours.” 

USGS: “The different colored lines show tilt in a specific direction at a specific station (see the legend in upper left corner of each plot). Station UWD is located near Uēkahuna, on the western rim of Kīlauea’s summit caldera. Station POC is located on the north rim of Pu‘u‘ō‘ō cone on the middle East Rift Zone of Kīlauea. These data are recorded by continuously operating electronic tiltmeters. Positive changes often indicate inflation of the magma storage areas beneath the caldera or on the middle East Rift Zone of Kīlauea, but may also result from heavy rainfall or, occasionally, instrumental malfunctions.”

From the USGS HVO summit observations published on Monday morning:

Weak intermittent glow from both vents was visible through the night, although glow was stronger and more frequent from the south vent. At the time of this report, both vents are quiet and emitting robust degassing plumes. Seismic tremor continues during the current pause and is punctuated by bursts every 5-10 minutes. At least some of the bursts were correlated with brighter periods of glow from the south vent and flames from the north vent. There were 3 shallow earthquakes located across the summit region during the past day.

USGS webcam view of the Kīlauea caldera down-dropped block and Halemaʻumaʻu crater from the east rim of the caldera, late Monday morning.

Analysis:

The initial rapid rebound of tilt and glow from both vents indicate that another fountaining episode is likely. The inflationary trend over the past several days has been interrupted by significant periods of no inflation or slight deflation recorded across all four summit tiltmeters that may impact the onset of episode 43 fountaining. Periods of weak deflation or no inflation have not been common in the early stages of repose between fountaining episodes. These changes in tilt rate are not predictable and create uncertainty in modeling the onset of episode 43 fountaining. Another deflationary event took place in the past 24 hours moving the forecast window back by a day. Preliminary models suggest the forecast window for the start of episode 43 fountaining is likely between March 6 and March 16. Additional data are needed to more accurately determine the forecast window.

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.