Volcano Watch: Adapting to an evolving eruption; revising Kīlauea’s alert level, aviation color code notifications

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

U.S. Geological Survey volcano alert level — an indication of ground-based status of volcanic activity — and aviation color code — indicating the severity of airborne volcanic hazards — can communicate relatively quickly what is happening at Kīlauea volcano on the Big Island.

Hawaiian Volcano Observatory — after the next projected lava fountaining episode of the ongoing episodic eruption at the summit, which will be Episode 44, sometime from April 6-14 — will change how it applies alert level and aviation color code to better convey hazards between and during eruptive episodes at Kīlauea summit.

As this historic episodic Kīlauea summit lava fountaining eruption continues, and its associated hazards changed with time, Hawaiian Volcano Observatory also adjusted its messaging to better inform the aviation sector and communities on the island affected by the related volcanic activity.

Now, more than a year into the eruption, pauses between eruptive episodes lengthened. Initial episodes were as short as several days apart, while recent episodes were separated by pauses of 3 weeks or longer.

With 43 episodes of observation, Hawaiian Volcano Observatory can characterize hazards associated with lava fountaining, and areas affected by fallout vary depending on wind conditions at the time.

Eruption-related hazards are greatly reduced during pauses in activity compared with while lava is fountaining.

The forecastable nature of these fountaining episodes allows Hawaiian Volcano Observatory to move between alert levels/aviation color codes with greater confidence than usually precedes the onset of a new eruption.

For most of the ongoing episodic eruption at the summit, Kīlauea alert level and aviation color code have been at Watch and Orange, respectively, during lava fountaining episodes and pauses.

Watch indicates a volcano is exhibiting escalating unrest or an eruption is underway but poses limited hazards, while Orange indicates an eruption is underway with no or minimal ash emissions — or there is heightened or escalating unrest with increased potential for an eruption.

Kīlauea alert level and aviation color code were elevated to Warning and Red, respectively, March 10 during Episode 43 lava fountaining, indicating a volcanic eruption was underway creating hazardous conditions on the ground and with significant emission of volcanic ash into the atmosphere.

National Oceanic and Atmospheric Administration Washington Volcanic Ash Advisory Center, which monitors and characterizes movement of airborne volcanic ash clouds in the region, reported the volcanic cloud produced by lava fountaining during Episode 43 reached higher than 22,000 feet above sea level.

The plume traveled to the northeast, with fallout causing closures in Hawaiʻi Volcanoes National Park and along Highway 11.

Ash fell over much of Puna and parts of North and South Hilo. National Weather Service issued an ashfall advisory which was subsequently elevated to a warning, and flights were canceled at Hilo International Airport.

Alert level and color code were lowered back to Watch and Orange, respectively, following the end of Episode 43.

After Episode 44 ends, assuming activity is similar to the first 43 episodes, Hawaiian Volcano Observatory will lower alert level and aviation color code for Kīlauea one level lower, to Advisory and Yellow, respectively.

Advisory and Yellow indicate that volcanic activity decreased significantly but continues to be closely monitored for possible renewed increase, which more appropriately convey the level of activity and associated ground and airborne hazards at Kīlauea during eruptive pauses.

Assigning Kīlauea the lower activity notifications during pauses also means when a new episode approaches or begins, Hawaiian Volcano Observatory can then raise them again to better reflect that the volcano is showing escalating unrest or that an eruption is underway with limited hazards and only minor ash emissions.

If a significant plume is generated and there are hazardous conditions on the ground, such as what occurred during Episode 43, Hawaiian Volcano Observatory will raise Kīlauea’s alert level and aviation color code to Warning and Red.

We appreciate the patience shown by residents and partners as we continue to adjust messaging to best communicate activity and hazards during Kīlauea’s lava fountaining eruption.

You can subscribe to receive volcano alert level and aviation color code notifications using the Volcano Notification Service.

VOLCANO ACTIVITY UPDATES

KĪLAUEA volcano

VOLCANO ALERT LEVEL: Watch

Kīlauea has been erupting episodically within the summit caldera since December 23, 2024. Episode 43 of lava fountaining happened for 9 hours on March 10. No unusual activity has been noted along Kīlauea’s East Rift Zone or Southwest Rift Zone.

WHAT’S NEXT? Summit region inflation since the end of Episode 43 indicates another fountaining episode is possible; models suggest Episode 44 could begin from April 6-14.

MAUNA LOA volcano

VOLCANO ALERT LEVEL: Normal

Mauna Loa is not erupting. Hawaiian Volcano Observatory reports in the most recent monthly volcano activity update for Mauna Loa that seismic activity decreased under the volcano compared with the previous month, with clustering of events under Mokuʻāweoweo and the upper Southwest Rift Zone still present.

A total of 86 earthquakes were detected during the February reporting period beneath Mauna Loa’s summit region, while 116 earthquakes were detected during the prior month.

Data from global positioning system instruments show variable rates of inflation at the summit throughout the past 6 months. This is associated with refilling of the summit reservoir system following the 2022 eruption.

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

EARTHQUAKES

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

• MAGNITUDE-2.5 earthquake at 9:58 a.m. March 28 located 2 miles southwest of Honoka‘a at a depth of 4 miles.
• MAGNITUDE-3 earthquake at 9:16 p.m. March 26 located 6 miles south of Pa‘auilo at a depth of 6 miles.
• MAGNITUDE-3.1 earthquake at 4:22 p.m. March 26 located 3 miles south-southeast of Pa‘auilo at a depth of 5 miles.

Visit the Hawaiian Volcano Observatory 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.