(BIVN) – Scientists have revised the forecasted start of the next episode of lava fountaining at Kīlauea volcano, as the ongoing summit eruption remains paused. 

The USGS Hawaiian Volcano Observatory says significant deflation was recorded across summit tiltmeters overnight. Models now show that the start of Episode 31 lava fountaining has likely been delayed to sometime between August 20th and August 23rd. 

The USGS HVO noted that moderate glow and sustained tremor “indicate that magma remains at relatively shallow depths beneath the active vents.” This was confirmed from imagery gathered on August 18th during an unmanned aerial systems flight. 

USGS: “This close-up view of the Kīlauea summit eruption’s north vent was captured during an uncrewed aircraft system (UAS) overflight conducted by Hawaiian Volcano Observatory scientists on August 18. Looking down to the southwest, the Halema‘uma‘u crater wall is out of view to the top of the frame. Lava was visible within the vent, with its height fluctuating in gas piston cycles every 10 minutes. During high stands, lava was flowing into a void in the eastern (lower-left) part of the vent. The scientists estimated that the lava pond measured approximately 15 meters (50 feet) across.” (USGS photo by M. Zoeller)

From the USGS update published on Tuesday:

Tilt was down by about 1.2 microradians overnight at UWD and 0.6 microradians at SDH, similar to decreases recorded several days prior to episode 30 fountaining episode. The past day also saw a small increase in seismicity located around the south caldera area yesterday well south and east of the cluster related to dike emplacement during the start of episode 30. Moderate to strong persistent glow was visible at both the north vent and the cracks above it overnight. The low-frequency tremor bursts characteristic of gas-pistoning of magma stopped around midnight and were replaced by more continuous tremor punctuated by bursts. Variations in gas-piston events are consistent with long term variability of shallow seismicity between episodes. The onset and persistence of glow suggest that magma is close to the surface. Images from an overflight on August 6th showed that episode 30 flows had covered nearly 80% the Halemaʻumaʻu crater floor, which now includes the old down dropped block.

The Uēkahuna tiltmeter (UWD) recorded about 22.5 microradians of deflationary tilt during episode 30. The end of the eruption was coincident with a rapid change from deflation to inflation at the summit and a decrease in seismic tremor intensity. The Uēkahuna tiltmeter (UWD) has recorded over 20 microradians of inflationary tilt since episode 30 ended but is now less than 18 microradians.

“Currently, there are no indications that any eruptive activity would occur outside of the summit region,” the USGS HVO added. The Volcano Alert Level for Kilauea remains at WATCH.