Volcano Watch: A new eruption and new era at Kilauea Volcano

  • USGS plot by H. DIETTERICH Plot showing rise of KIlauea’s summit lava lake since the eruption in Halema‘uma‘u began Dec. 20. Since then, laser rangefinder measurements of the lava lake surface are made 2–3 times per day. Photos compare the lava lake on the morning of Dec. 21, when it was about 289 ft (87 m) deep, to the evening of Dec. 23, when it was about 511 ft (155 m) deep. For comparison, the water lake that was present in Halema‘uma‘u until the evening of Dec. 20 was 167 ft (51 m) at its deepest, prior to vaporizing.

‘Twas the Sunday before Christmas, the eve of the winter solstice, and festive holiday lights blinked of bright red and green. And then, shortly after 9:30 p.m. on Dec. 20, so did the Hawaiian Volcano Observatory’s volcano alert level/aviation color codes for Kilauea!

In the near blink of an eye, Kilauea Volcano’s Normal/Green status was quickly increased to Warning/Red as lava returned to Halema‘uma‘u.


There was concern that magma- or lava-water interactions might result in explosive activity at Kilauea’s summit because of the intriguing water lake that formed within Halema‘uma‘u during the past 17 months. However, the water lake quickly boiled away in large billows of steam that reached more than 10 km (30,000 ft) into the sky, as streams of lava fed by fountaining vents in the crater walls filled the space where the water once pooled.

The water lake was replaced by a lava lake.

As described in recent “Volcano Watch” articles and information statements, HVO observed increasing levels of seismicity and ground deformation at Kilauea summit for several weeks prior to this eruption. Precursory signals were not continuous, however, as seismic swarms and deformation transients would diminish and return to background levels before ramping up again, such as they did before and after the small intrusion on Dec. 2. No changes in gas emissions or the state of the water lake were observed.

Nevertheless, based on patterns of earthquakes and deformation, HVO was planning to increase Kilauea’s alert level/aviation color code to Advisory/Yellow on Monday, Dec. 21, but the eruption started the night before instead!

The eruption was preceded by an earthquake swarm beneath the summit at about 8:30 p.m. Ground deformation transients detected by summit tiltmeters immediately before the eruption were surprisingly small, and there were no changes in gas emissions or other data. A bright glow and vigorous steam plume, generated by the boiling water lake in Halema‘uma‘u, was subsequently observed on HVO webcams beginning at approximately 9:30 p.m.

HVO elevated Kilauea’s volcano alert level to Warning and its aviation color code to Red on Dec. 20 as the progression of events was uncertain and there was concern for potential steam-driven explosions and related hazards.

HVO scientists responded immediately and visually confirmed from the field that lava was visible within Halema‘uma‘u. The steam plume dissipated shortly thereafter.

The eruption began as three fissures opened in the north and northwest walls of Halema‘uma‘u, behavior that is not uncommon for Kilauea. When magma migrates upward to the surface as a dike, it does so along the path of least resistance, which is on crater walls versus the crater floor.

On Dec. 21, HVO lowered Kilauea’s volcano alert level to Watch, meaning “eruption is underway but poses limited hazards.” The aviation color code was lowered to Orange, meaning “eruption is underway with no or minor volcanic-ash emissions.”

At present, the primary hazard of concern regarding this new activity at Kilauea’s summit is the high level of volcanic gas, which is generating volcanic air pollution (vog) downwind.

As of Dec. 24, two vents continued to feed the rapidly enlarging lava lake filling Halema‘uma‘u crater. If the eruption continues at that rate, these two remaining vents will soon be inundated, possibly by the time this article is published. As of 7 a.m. Thursday, the lake was 169 m (554 ft) deep. The surface area was 25 ha (69 acres) and lake shape was still roughly oval, with an east-west length of 715 m (780 yds) and a north-south width of 460 m (500 yds).

The eruption is currently confined to Halema‘uma‘u within Hawaii Volcanoes National Park and monitoring data show no changes to the lower East Rift Zone or other parts of the volcano. Seismicity and ground deformation have been concentrated at the summit and the eruption is stable, with no indications of imminent summit collapse like in 2018.

This eruption has already provided new and exciting scientific observations, which we’ll be sharing in future “Volcano Watch” articles. For now, check the Kilauea “Current Eruption” web page for information and field updates about the ongoing activity.

A short period of quiescence — about 28 months following the 2018 eruption — has ended for Kilauea Volcano. The summit water lake era has come and gone and a new era of eruption activity is upon us.

Lava has returned to Halema‘uma‘u.

Volcano activity updates

Kilauea Volcano is erupting. Its USGS Volcano Alert level is at Watch (www.usgs.gov/natural-hazards/volcano-hazards/about-alert-levels). Kilauea updates are issued daily.

The eruption at Kilauea Volcano’s summit continues. Lava activity is confined to Halema‘uma‘u from two vents on the north and northwest sides of the crater. As of 7 a.m. Thursday morning, the growing lava lake was 169 m (554 ft) deep. Summit tiltmeters continue to record steady deflationary tilt. Sulfur dioxide emission rates remain high, estimated at about 35,000-40,000 tonnes per day as of Dec. 23. Seismicity remains elevated but stable, with a few minor earthquakes and tremor fluctuations related to the vigor of the fissure fountaining.

For the most current information about the eruption, visit www.usgs.gov/volcanoes/kilauea/current-eruption.

Mauna Loa is not erupting and remains at Volcano Alert Level Advisory. This alert level does not mean an eruption is imminent or that progression to eruption from current level of unrest is certain. Mauna Loa updates are issued weekly.

This past week, about 60 small-magnitude earthquakes were recorded beneath the upper elevations of Mauna Loa; most of these occurred at depths of less than 8 kilometers (about 5 miles). The largest recorded earthquake was a M2.5 beneath the volcano’s northwest flank at 9:21 p.m. Dec. 23. The earthquake activity on Mauna Loa’s northwest flank, which began Dec. 4, has subsided to average long-term trends.

GPS measurements continue to show slow, long-term summit inflation, consistent with magma supply to the volcano’s shallow storage system. Gas concentrations and fumarole temperatures at the summit and Sulphur Cone on the Southwest Rift Zone remain stable. Webcam views have revealed no changes to the landscape during the past week.

For more information about current monitoring of Mauna Loa Volcano, visit https://volcanoes.usgs.gov/volcanoes/mauna_loa/monitoring_summary.html

There were five events with three or more felt reports in the Hawaiian Islands during the past week: a M2.0 earthquake 2 km (1 mi) WNW of Pahala at 27 km (17 mi) depth at 10:43 p.m. Dec. 20, a M4.4 earthquake 14 km (9 mi) S of Fern Forest at 6 km (4 mi) depth at 10:36 p.m. Dec. 20, a M2.9 earthquake 11 km (7 mi) SSE of Fern Forest at 6 km (4 mi) depth at 6:09 p.m. Dec 18, a M3.1 earthquake 5 km (3 mi) SWS of Volcano at 2 km (1 mi) depth at 5:24 p.m. Dec.18 and a M3.3 earthquake 6 km (4 mi) SW of Pahala at 31.4 km (19 mi) depth at 3:04 p.m. Dec. 19.

HVO continues to closely monitor Kilauea’s ongoing eruption and Mauna Loa for any signs of increased activity.


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

Volcano Watch is a weekly article and activity update written by U.S. Geological Survey Hawaiian Volcano Observatory scientists and affiliates.

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