Halemaʻumaʻu eruption · episode 40 of 55
Kīlauea episode 40
Episode 40 of Kīlauea's Halemaʻumaʻu eruption began at 8:22 a.m. HST on January 12, 2026 and ended at 6:04 p.m. HST the same day. USGS gives the duration as 10 hours. HVO's Uēkahuna tiltmeter (UWD) recorded about 17 microradians of deflation during the episode. HVO notes: North and south vents active; north vent dominant.
Episode 40 at a glance
- Start (HST)
- January 12, 2026, 8:22 a.m.USGS timeline
- End (HST)
- January 12, 2026, 6:04 p.m.USGS timeline
- Duration
- 10 hoursUSGS timeline
- UWD tilt (deflation)
- about 17 microradiansHVO notice
- Max fountain height
- about 250 mUSGS timeline
- Lava erupted
- about 5.5 million m³USGS timeline
- Pause that followed
- 12 daysUSGS timeline
End: the USGS timeline gives “January 12, 2026 - 6:04 p.m.”, but an HVO notice at the time said: “Episode 40 lava fountaining from the north vent stopped at approximately 7:04 p.m. HST on January 12 after 9.7 hours of sustained fountaining.”
In HVO's words
The sentences these figures come from, quoted from USGS Hawaiian Volcano Observatory notices.
“The Uēkahuna tiltmeter (UWD) recorded about 17 microradians of deflationary tilt during episode 40.”
Other HVO notices about episode 40 gave: 17.5 microradians.
HVO notices about episode 40
- Volcano Activity Notice · Jan 12, 2026, 8:34 a.m. HST
- Volcano Activity Notice · Jan 12, 2026, 6:13 p.m. HST
- Daily Update · Jan 13, 2026, 9:14 a.m. HST
- Information Statement · Jan 14, 2026, 10:05 p.m. HST
Daily updates: USGS Kīlauea volcano updates. Full table: USGS Timeline of Eruptive Episodes.
Times are Hawaiʻi-Aleutian Standard Time (HST). Start and pause times, durations, fountain heights and lava volumes come from the USGS Hawaiian Volcano Observatory's Timeline of Eruptive Episodes; tilt figures and episodes not yet in that table are quoted from HVO notices. USGS describes these as unreviewed, preliminary estimates that are subject to revision. Durations for episodes 17 and earlier may include precursory activity, and HVO rounds durations to the nearest hour, half-hour or day. A blank cell means HVO hasn't published that figure in a form we could read; we don't estimate it.
Credit: U.S. Geological Survey. This archive is generated automatically and is not an official USGS product.