Volcano Watch — The pressure is on, within Kīlauea and for volcanologists to foretell what’s next

Episodic eruptions have occurred before on Kīlauea at the start of the 1983 Puʻuʻōʻō and the 1969 Maunaulu eruptions (44 and 12 episodes each) on the middle East Rift Zone, and during the 1959 Kīlauea Iki summit eruption (17 episodes). While the recent Kīlauea summit eruption is currently paused, persistent night glow from the vent and continued strong degassing indicate molten magma is probably within 150–300 feet (50–100 meters) of the surface within the vent.

Sufficient pressure could push magma up to the surface to start another eruptive episode. Fountaining is driven by rapid volume expansion of gas in fresh lava but is commonly preceded by periods of eruption of sluggish degassed flows. Dense degassed material is pushed out of the vent like a cork from a champagne bottle, allowing gas-rich magma to rise rapidly and fountain.

Episodes are marked by the onset of lava fountains and rapid deflation of the source magma chamber. Pauses between fountain episodes are usually accompanied by reinflation of the summit. A new episode begins when the system builds up enough pressure to force magma to the surface again.

The main feature of episodic eruptions is their repeatability, which allows patterns to be identified. Inflation following episodes 1 and 2 of the recent eruption at the summit of Kīlauea resulted in 6 microradians of ground tilt a tiltmeter north of the caldera, near Uēkahuna bluff, indicating the pressure increase required at that time for the eruption to resume.   

Following episode 3, Kīlauea has inflated and the 6 microradian level was reached about 4:30 p.m. HST Wednesday, January 8 afternoon (5 days after episode 3 paused on Friday, January 3 at 8:40 p.m. HST). That amount of inflation had been the minimum amount of pressure required previously for this eruption to restart. However, the large deflation that accompanied the prolonged fountaining of episode 3 suggests the system might need more inflation to reach the pressure necessary for eruptive activity to resume.

The longer the vent sits without eruption, the more time magma within the vent has to cool and it could reach a point that the eruption can’t restart. Assuming the vent remains open, indicated by continued glow and degassing, and inflation rate remains constant, a new episode could potentially begin sometime between January 8 and January 13, when ground tilt at Uēkahuna is expected to reach 12 microradians, about double prior post-fountain tilt increases.

HVO scientists have been developing tools estimate times of high probabilities of eruptions occurring on Kīlauea for the past several years. Complex models using GPS monitoring data have been created to track when the summit approached pressurization levels similar to previous eruptions.

Models run in October of 2024 indicated that Kīlauea was likely to reach pressurization levels where an eruption could happen between mid-December 2024 and mid-January 2025. This model also relies on the eruption being preceded by increasing numbers of earthquakes in the region where the eruption is most probable.

“Windows” of high probability for new eruptions or new fountaining episodes aren’t true forecasts. A forecast requires knowing what will happen, where it will happen, and most importantly, an accurate estimate of when it will happen. Forecasting when an eruption will happen is the most difficult part but is very important so communities have more time to prepare if needed. 

Whenever HVO raises alert levels to ORANGE/WATCH, we are issuing a more precise forecast for a pending eruption or intrusion within minutes to hours near the summit or hours to days further along Kīlauea’s rift zones.

HVO scientists are constantly improving models of volcanic behavior—past, present and future—which allows us to forecast eruption time windows with greater accuracy and longer advance warning. This is an essential part of HVO’s mission to reduce the impacts of volcanic eruptions and communicate the results of our work to emergency managers and the public. 

Volcano Activity Updates

Kīlauea is erupting. Its USGS Volcano Alert level is ADVISORY.

Eruptive activity at vents in the southwest portion of Kīlauea caldera paused the evening of January 3, 2025. Low inflationary tilt at the summit since then suggests that the eruption could resume in the coming days to weeks, and lava was observed within the inactive vents during a monitoring overflight the morning of January 10. Recent eruptive activity has been confined to Halemaʻumaʻu and the down-dropped block within the caldera. No unusual activity has been noted along Kīlauea’s East Rift Zone or Southwest Rift Zone. Sulfur dioxide emission rates are elevated in the summit region during eruptive activity. Earthquake rates in the Southwest Rift Zone and upper to middle East Rift Zone remained comparable to the previous week. Ground deformation rates outside of the summit region remained steady. 

Mauna Loa is not erupting. Its USGS Volcano Alert Level is at NORMAL.

Three earthquakes were reported felt in the Hawaiian Islands during the past week: a M3.0 earthquake 10 km (6 mi) S of Waikoloa at 23 km (14 mi) depth on Jan. 7 at 9:44 a.m. HST, a M2.7 earthquake 11 km (6 mi) SSW of Leilani Estates at 6 km (4 mi) depth on Jan. 4 at 3:14 a.m. HST, and a M3.0 earthquake 39 km (24 mi) SE of Nāʻālehu at 30 km (19 mi) depth on Jan. 2 at 4:18 p.m. HST.

HVO continues to closely monitor Kīlauea and Mauna Loa.

Please visit HVO’s website for past Volcano Watch articles, Kīlauea and Mauna Loa updates, volcano photos, maps, recent earthquake information, and more. Email questions to askHVO@usgs.gov.