Volcano Watch: Happy New Year, Hawaiian volcano style

“Volcano Watch” is a weekly article and activity update written by U.S. Geological Survey Hawaiian Volcano Observatory scientists and affiliates. Note: The summit eruption of Kīlauea volcano paused for a third time shortly before 9 a.m. Friday, after this week’s “Volcano Watch” was written and submitted for publication.

People around the world greet the New Year with fireworks and other celebrations.

Hawaiʻi Volcanoes National Park visitors got to greet 2025 with displays of lava fountaining from the southwest part of Kaluapele, the summit caldera of Kīlauea volcano.

The eruption is in its third episode, with pauses and resumptions of eruptive activity correlating with the level of pressurization within the magma chambers beneath the summit region of the volcano.

Two important instruments for monitoring the level of pressurization are the UWD and SDH tiltmeters, which measure how the ground is tilting as magma chambers beneath the summit inflate or deflate.

Magma chambers beneath Kīlauea summit region showed increasing pressurization in the months leading up to the eruption.

Fountains of lava burst from the floor of Halemaʻumaʻu at 2:20 a.m. Dec. 23, 2024, rapidly reaching heights up to nearly 300 feet.

These vigorous lava fountains fed lava flows that covered most of the floor of Halemaʻumaʻu Crater within Kaluapele that dropped during the 2018 caldera collapse, referred to informally as the “downdropped block.”

Lava being erupted on the surface rapidly relieved some of the pressure that had built up in the magma storage areas. The summit tiltmeters showed strong deflationary tilt immediately after the eruption began, until about 4 p.m. Dec. 23, when the lava fountains ceased.

At this point, lava began flowing back into the vent, in a phenomenon called “drainback,” and tilting direction at UWE and SDH switched to inflationary.

This indicated that pressure was again building in the magma chambers.

Inflationary tilt continued overnight, and lava began slowly erupting again at about 8 a.m. Christmas Eve, Dec. 24, 2024.

At about 11 a.m., lava fountaining resumed and tiltmeters once again began measuring rapid deflationary tilt during this second episode of the eruption, which continued for the next 24 hours.

Lava flows again covered most of the lower elevation southwest portion of Kaluapele and the eruption abruptly stopped again by about 11 a.m. Christmas Day, Dec. 25, 2024.

Just as they did during the earlier pause, summit tiltmeters began measuring inflationary tilt, indicating pressure was again accumulating in the magma chambers. Inflation continued through the following night until the eruption resumed at 8 a.m. Dec. 26, 2024.

Slow lava flows remained close to the vent until the evening of Dec. 27, 2024, when low-level lava fountaining resumed.

Lava fountaining gradually increased in vigor as slow inflation continued until the afternoon of Dec. 29, 2024.

Since then, Kīlauea summit tiltmeters have continued to measure deflationary tilt, with lava fountaining feeding lava flows in the southwest portion of Halemaʻumaʻu.

This interplay of eruption episodes and variations in magma chamber pressure leads to lots of questions. Most of all: “Why has the eruption been stopping and starting so dramatically?”

The association of drainback with magma chamber inflation is puzzling; one would expect increased eruption rate if pressure is increasing.

The answer could lie in the gas content of lava and extent to which gas bubbles also drive eruption.

Like releasing the cap off a soda, opening a eruptive vent can result in a combination of pressure and bubble driven flow.

Erupted lava that “drains back” into the vent is much denser than fresh gas-rich lava. The drainback lava forms a plug, like putting a cork back into a champagne bottle, that allows the magma chamber to repressurize.

The dense lava is slowly pushed out at the beginning of the next episode until new, gas-rich lava gets close enough to the surface to vesiculate and restart fountaining.

The third episode of the eruption is ongoing as of this writing.

Hawaiian Volcano Observatory continues to closely monitor the activity, and views of the activity are available on observatory webcams, including a livestream.

The recent eruption is a reminder that in Hawai‘i, we live on the flanks of volcanoes, some of which are active.

Volcano Awareness Month is a great opportunity for you to increase your knowledge about volcanic activity in the Aloha State. Join us at one of the many events throughout January on Hawaiʻi Island, and don’t forget to submit your art or poetry to our contest!

You can learn more online.

Volcano Activity Updates

Kīlauea is erupting. Its USGS Volcano Alert level is at Watch.

During the past week, vents in the southwest portion of Kaluapele, the summit caldera, have continued producing lava flows covering the western portion of the crater floor during sustained lava fountaining.

Eruptive activity has been confined to Halemaʻumaʻu Crater and the downdropped 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.

Five earthquakes were reported felt in the Hawaiian Islands during the past week:

• A magnitude-3.1 located 6 miles east of Pāhala at a depth of 18 miles at 10:51 a.m. Jan. 1.
• A magnitude-2.6 located 1 mile west-southwest of Pāhala at a depth of 19 miles at 1:06 a.m. Dec. 30, 2024.
• A magnitude-2.7 located 1 mile west-southwest of Pāhala at a depth of 20 miles at 11:35 p.m. Dec. 29, 2024.
• A magnitude-3.7 located 1 mile southwest of Pāhala at a depth of 18 miles at 11:19 p.m. Dec. 29, 2024.
• A magnitude-4.3 located less than a mile west-southwest of Pāhala at a depth of 19 mi at 11:04 p.m. Dec. 29.

Hawaiian Volcano Observatory continues to closely monitor Kīlauea and Mauna Loa.

Vsit the volcano observatory’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.