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 HVO geologist Natalia Deligne. 

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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 have developed it when our volcanoes have been relatively quiet—away from the stress of a crisis response—to make deliberate choices and decisions on 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 Hawai’i consists of five 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 Hawaii 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 over the course of three months during the same eruption. In 2022, Mauna Loa erupted for the first time in 38 years; fortunately, the impacts were minimal. HVO monitored these volcanic events, working closely with landholding agencies such as the Hawaiʻi Volcanoes National Park, and emergency managers, led by the Hawaiʻi County Civil Defense Agency.

The Interagency Volcano Plan draws on the formal and informal USGS 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 two and a half years—interrupted by Covid-19 outbreaks, 6 eruptions, and other emergency responses—building on regular discussions between the three agencies on how to best work together during volcanic crises. It draws from elements of other USGS volcano observatories’ 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 may 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 may include all the unrest hazard and also active vents (including fissures), lava flows, lava bombs, tephra fall (including ash), laze, and (rare in Hawaii) 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 three agencies work together during volcanic crises, with the understanding that circumstances may 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 three agencies that are part of this first version of the Interagency Volcano Plan are based on the Island of Hawaiʻi and were identified as having the most significant opportunities to improve interagency coordination in the USGS 2018 Kīlauea eruption after-action review. Additional agencies will be incorporated in future versions of the Interagency Volcano 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 continues at Kīlauea's summit and upper-to-middle East Rift Zone. Over 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. Over the past week, Kīlauea's summit showed overall slow inflation with relatively little ground deformation recorded in the upper-to-middle East Rift Zone regions. Unrest may 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 M3.0 earthquake 7 km (4 mi) NE of Honoka‘a at -1 km (0 mi) depth on August 28 at 8:22 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.