Volcano Watch: Introducing the Island of Hawaiʻi Interagency Operations Plan for Volcanic Eruptions

“Volcano Watch” is a weekly article and activity update written by U.S. Geological Survey Hawaiian Volcano Observatory scientists and affiliates. This week’s article was written by geologist Natalia Deligne. It was delivered a day late because of Hawaiian Volcano Observatory website maintenance. Posting of this article on the observatory’s website will be delayed.

Last month, the Hawaiʻi County Civil Defense Agency, Hawaiʻi Volcanoes National Park and the U.S. Geological Survey Hawaiian Volcano Observatory adopted the Island of Hawaiʻi Interagency Operations Plan for Volcanic Eruptions (hereafter referred to as the Interagency Volcano Plan).

While our three agencies have worked well responding to volcanic unrest and eruptions together for decades, the Interagency Volcano Plan puts our practices down on paper.

We developed the plan while our volcanoes have been relatively quiet — away from the stress of a crisis response — to make deliberate choices and decisions about how we can best serve our community and visitors to the Island of Hawaiʻi going forward, strengthening the partnership between the three agencies in the process.

Why is the Interagency Volcano Plan needed?

The Island of Hawaiʻi consists of 5 volcanoes. Four volcanoes — Kīlauea, Mauna Loa, Hualālai and Mauna Kea — are considered active and three of them have erupted since the year 1800.

Based on 24 factors, including eruptive history, eruptive style and associated hazards and population exposure, the 2018 update to the U.S. Geological Survey National Volcanic Threat Assessment identified Kīlauea and Mauna Loa as very high threat volcanoes, Hualālai as a high threat volcano and Mauna Kea as a moderate threat volcano.

For context, there are only 18 very high threat volcanoes in the United States.

Volcanic eruptions in Hawaiʻi can profoundly impact local communities, infrastructure, human health, agriculture, businesses and tourism. A well-coordinated volcanic incident response can minimize loss of life, injury, social and economic disruption and long-term consequences.

This requires timely, accurate, relevant and trusted information to threatened and impacted communities, and to the general population for situational awareness.

In 2018, lava flows from the lower East Rift Zone of Kīlauea destroyed 612 residences. At Kīlaueaʻs summit, Hawaiʻi Volcanoes National Park and neighboring communities were affected by thousands of earthquakes as the summit incrementally collapsed throughout the course of 3 months during the same eruption.

In 2022, Mauna Loa erupted for the first time in 38 years; fortunately, the impacts were minimal.

The Hawaiian Volcano Observatory monitored these volcanic events, working closely with landholding agencies such as Hawaiʻi Volcanoes National Park and emergency managers, led by the Hawaiʻi County Civil Defense.

The Interagency Volcano Plan draws on the formal and informal U.S. Geological Survey after-action reviews for the 2018 Kīlauea and 2022 Mauna Loa eruptions, respectively, to improve planning and response protocols.

The development of the Interagency Volcano Plan spanned nearly 2.5 years — interrupted by COVID-19 outbreaks, 6 eruptions and other emergency responses — building on regular discussions between the 3 agencies about how to best work together during volcanic crises.

It draws from elements of other U.S. Geological Survey volcano observatory interagency coordination plans but is uniquely developed for the Island of Hawaiʻi.

The Interagency Volcano Plan addresses volcanic unrest and eruption response coordination on the Island of Hawaiʻi.

Unrest hazards can include seismicity, ground deformation (including ground cracks and subsidence), volcanic gases and air pollution (vog) and associated hazards.

Not all unrest leads to an eruption.

Eruptive hazards can include all the unrest hazards and also active vents (such as fissures), lava flows, lava bombs, tephra fall (including ash), laze and (rare in Hawaiʻi) pyroclastic density currents.

The Interagency Volcano Plan is intended to be a guide, as each volcanic incident is unique.

It is supported by detailed standing operating guidelines and/or standing operating procedures maintained by each participating agency.

The Interagency Volcano Plan documents how the 3 agencies work together during volcanic crises, with the understanding that circumstances might require situation-specific changes and adaptations.

It covers the roles and responsibilities of each agency, how notification of a volcanic situation is completed, jurisdictional areas of responsibility, incident command, information flow and aviation coordination.

The 3 agencies that are part of this first version of the plan were identified as having the most significant opportunities to improve interagency coordination in the U.S. Geological Survey 2018 Kīlauea eruption after-action review.

Additional agencies will be incorporated in future versions of the plan, and work on version 2 is slated to start in October 2025.

Volcano Activity Updates

Kīlauea is not erupting. Its USGS Volcano Alert level is Advisory.

Seismic activity and ground deformation continue at Kīlauea’s summit and upper-to-middle East Rift Zone.

During the past week, about 400 earthquakes were detected beneath Kīlauea’s upper East Rift Zone and about 100 events were detected between Maunaulu and Puʻuʻōʻō in the middle portion of the East Rift Zone within Hawaiʻi Volcanoes National Park.

Kīlauea’s summit showed overall slow inflation with relatively little ground deformation recorded in the upper-to-middle East Rift Zone regions throughout the same time frame.

Unrest can continue to wax and wane with changes to the input of magma in these areas. Changes can occur quickly, as can the potential for eruption.

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

One earthquake was reported felt in the Hawaiian Islands during the past week: A magnitude-3 earthquake 4 miles northeast of Honoka‘a at a depth of 0 miles at 8:22 p.m. Aug. 28.

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

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.