Hawai'i Volcano Blog

‘Volcano Watch’: Today’s family of five USGS volcano observatories began with HVO more than 111 years ago

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

The Hawaiian Volcano Observatory (HVO) was founded in 1912. Today, more than 111 years later, it is one of five volcano observatories supported by the U.S. Geological Survey (USGS).

The Hawaiian Volcano Observatory (HVO), founded in 1912 by Thomas A. Jaggar, was the first of five volcano observatories supported by U.S. Geological Survey (USGS) today. The “Technology Station” (circled) on the eastern rim of Halema‘uma‘u crater — at the summit of Kīlauea — was the first, though temporary, of several buildings HVO has occupied since its founding. (USGS photo by Frank A. Perret)

HVO staff has grown from one geologist, Thomas A. Jaggar, in 1912 to more than 30 people today. This team includes scientists and specialists in geology, geophysics, geochemistry, field engineering and telemetry, information technology, administration, public communications and more. Hundreds of volunteers, students and visiting scientists — many from the University of Hawaiʻi — have also provided valuable assistance to HVO through the years.

HVO methods of observing and analyzing data from instruments and field studies have changed dramatically since Jaggar’s time.

Presently, our monitoring network consists of more than 200 sensors, including seismometers, global positioning systems (GPS), tiltmeters, infrasound, gas detectors and thermal/visual cameras. These sensors transmit data to HVO 24 hours a day in order to track activity and support research into how volcanoes work. Remote sensing data from instruments on aircraft, including unmanned aircraft systems piloted by HVO, as well as satellites provide additional coverage.

When HVO was founded, Hawaiʻi was not yet a state. Hawaiʻi Volcanoes National Park did not yet exist. A lake of molten lava was on the floor of Halemaʻumaʻu crater at the summit of Kīlauea volcano, similar to what we’ve seen throughout the past three years. HVO was originally operated with support from the Massachusetts Institute of Technology (MIT) and the Hawaiian Volcano Research Association. It was later managed by a series of federal agencies including the U.S. Weather Bureau, the National Park Service and now the USGS.


The USGS became the permanent administrator of HVO in 1947. Based on HVO’s success, the USGS went on to establish additional observatories to monitor and study 161 active volcanoes throughout the United States and U.S. territories.

HVO focuses on the six active volcanoes in Hawaiʻi including two “very high threat” volcanoes — Kīlauea and Mauna Loa — and one “high threat volcano,” Hualālai, all of which are on the Big Island. HVO also monitors active volcanoes in American Samoa.

Cascades Volcano Observatory (CVO) was authorized in 1980 following the eruption of Mount St. Helens and formally dedicated in 1982. CVO focuses on volcanoes in Washington, Oregon and Idaho. CVO is also home to the USGS Volcano Disaster Assistance Program which aids crisis response at volcanoes around the world.

Alaska Volcano Observatory (AVO) was founded in 1988 following the 1986 eruption of Augustine Volcano. AVO, a collaboration between the USGS, the University of Alaska Fairbanks and the state of Alaska, focuses on volcanoes in Alaska and the Commonwealth of Northern Mariana Islands.

Yellowstone Volcano Observatory (YVO) was founded in 2001. YVO, a consortium of nine state and federal agencies, focuses on volcanic activity in the Yellowstone Plateau region and intermountain western U.S. states.


California Volcano Observatory (CalVO) was formed in 2012. CalVO, with expanded scope beyond the Long Valley Observatory (LVO) established in 1982, focuses on volcanoes in California and Nevada.

The collective knowledge, skills and experience of people at these five observatories is extensive and complementary. Staff communicate and travel between observatories in true team fashion. HVO staff help install instruments on volcanoes outside Hawaiʻi and vice versa.

The lead scientist for the Kīlauea Seismic Imaging Project described in a recent “Volcano Watch” article is based at CVO, and many scientists from other observatories are traveling to Hawaiʻi to assist. Staff from all observatories assisted HVO during the 2018 Kīlauea and 2022 Mauna Loa eruptions.

HVO also has supported eruption responses at other volcanoes such as Mount St. Helens, and will help respond to future events at other volcanoes.

Fulfilling our mission involves constant evolution and holistic future planning. As an example of preparing for possible future scenarios, HVO is participating in a virtual “tabletop exercise” led by CVO to practice responding to simulated unrest at a volcano in Oregon. And on the national scale, we are collectively developing the National Volcano Warning System to ensure that volcanoes are monitored at levels commensurate to their threats.


HVO has grown and changed significantly during the past 111 years. Together with four other USGS volcano observatories established since that time, our mission continues — to assess hazards, issue warnings and advance scientific understanding to reduce the impacts of volcanic eruptions — and to communicate the results of our work to the public, emergency managers and the scientific community. Imua!

Volcano Activity Updates

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

Webcams show no signs of active lava in Halemaʻumaʻu crater, at the summit of Kīlauea in Hawai‘i Volcanoes National Park. During the past week, summit tiltmeters generally showed mild inflation and slightly elevated seismicity. The summit sulfur dioxide (SO2) emission rate was most recently measured April 26, when it totaled 75 tonnes per day.

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

Webcams show no signs of activity on Mauna Loa. Seismicity remains low. Summit ground deformation rates show inflation above background levels, but this is not uncommon following eruptions. SO2 emission rates are at background levels.

There were eight earthquakes with three or more felt reports in the Hawaiian Islands during the past week: a M3 earthquake 14 km (8 mi) S of Fern Forest at 4 km (3 mi) depth on April 26 at 10:09 p.m. HST, a M3.9 earthquake 10 km (6 mi) NNE of Honaunau-Napoopoo at 26 km (16 mi) depth on April 26 at 7:27 p.m. HST, a M4.2 earthquake 12 km (7 mi) ESE of Pāhala at 29 km (18 mi) depth on April 26 at 4:30 p.m. HST, a M2.4 earthquake 3 km (1 mi) SE of Volcano at 1 km (0 mi) depth on April 23 at 2:59 p.m. HST, a M2.5 earthquake 2 km (1 mi) SSE of Volcano at 1 km (0 mi) depth on April 22 at 2:33 p.m. HST, a M4.1 earthquake 2 km (1 mi) SSE of Volcano at 1 km (0 mi) depth on April 22 at 2:23 p.m. HST, a M3.2 earthquake 3 km (1 mi) SSW of Pāhala at 34 km (21 mi) depth on April 21 at 10:17 p.m. HST, a M2.2 earthquake 2 km (1 mi) SSE of Volcano at 1 km (0 mi) depth on April 21 at 9:59 p.m. HST.

HVO continues to closely monitor Kīlauea and Mauna Loa.

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.

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