The Hawaiian Volcano Observatory is no rookie when it comes to using flight to assist with monitoring Hawaiian volcanoes.

Helicopters and fixed-wing aircraft have transported HVO volcanologists for decades, giving them access for visual and thermal observations, equipment maintenance and other geophysical and geochemical measurements. But the 2018 eruption of Kilauea Volcano presented an opportunity for HVO, part of the U.S. Geological Survey, to adopt a new airborne technology — unmanned aircraft systems (UAS, or drones) — to better monitor the eruption than with manned flight alone.

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Previously, the University of Hawaii at Hilo used UAS to map the 2014 Pahoa lava flow. Other external collaborators also previously flew short campaigns at Kilauea’s summit and Pu‘u ‘O‘o with permission of Hawaii Volcanoes National Park. But before the 2018 eruption, the USGS itself had not employed UAS to monitor an eruption in Hawaii.

In 2018, however, UAS teams from throughout the USGS, as well as other agencies within the U.S. Department of the Interior, were mobilized for the Kilauea eruption response. Through most of the activity, UAS crews worked 24/7, sometimes splitting into multiple teams so measurements could be made at the summit and lower East Rift Zone of Kilauea simultaneously.

The most basic capability of the UAS during the 2018 eruption was simple video imaging and streaming. This allowed for documentation of eruptive features that would not otherwise have been accessible for study because of hazardous conditions.

In a more practical sense, UAS imaging also offered enhanced situational awareness for the eruption response. UAS images helped identify where new lava breakouts were happening or were likely to occur. In one instance, a USGS UAS helped with the evacuation of a Puna resident as a lava flow quickly approached.

Some of the UAS were outfitted with thermal cameras, which provided images used to create detailed maps of the lava flows. Thermal imagery also was used to identify the hottest, most active portions of the flow field, which was particularly useful when visible images were not able to differentiate between slightly older and slightly newer flows.

More technical applications of UAS-based imaging included the creation of digital elevation models (DEMs) and measurements of lava flow speeds within channels. By using imagery to determine the height of newly emplaced lava, the new DEMs could be compared to pre-eruption DEMs to calculate the volume of lava erupted.

At Kilauea’s summit, DEMs helped HVO assess the new landscape of the collapsing caldera and determine just how much collapse was occurring. Along the rift zone, videos taken above fast-flowing lava channels helped with calculations of how much and how quickly lava was erupting from the fissures.

Beyond the UAS imaging opportunities, the 2018 eruption was the first time the USGS mounted gas sensors on UAS in Hawaii. The fissures were too dangerous to approach on foot to measure the gas chemistry, but a multi-gas sensor mounted on a UAS helped determine the chemistry of the eruptive plumes.

Likewise, at the summit, with collapse events and potential explosion hazards, ground-based gas measurements within Kilauea caldera were not possible. UAS-based measurements were the only safe method for measuring the location, chemistry and amount of volcanic gas released at the summit.

Having UAS capabilities for the 2018 eruption enabled HVO to obtain crucial data that would otherwise have been difficult or impossible to obtain. However, you might have noticed that while this article refers to UAS teams from throughout the USGS traveling to Hawaii for the eruption response, it makes no mention of in-house HVO pilots. That’s because, in 2018, HVO didn’t have any certified UAS pilots with the skills required for flying in hazardous areas. But that will change in the coming months.

Several HVO staff members will become licensed UAS operators later this year, allowing HVO to add UAS capabilities to our monitoring repertoire. We will then be able to use UAS to aid in our mission-critical monitoring work and will be poised to deploy UAS at a moment’s notice to collect important datasets the next time a Hawaiian volcano acts up.

Volcano activity updates

Kilauea Volcano is not erupting and its USGS Volcano Alert level remains at Normal. For definitions of USGS Volcano Alert Levels, see https://volcanoes.usgs.gov/vhp/about_alerts.html.

Rates of deformation, gas release and seismicity on Kilauea did not change significantly during the past week.

Since early March, GPS stations and tiltmeters at Kilauea’s summit have recorded deformation consistent with slow magma accumulation within the shallow portion of the summit magma system. However, gas measurements have not indicated shallowing of large volumes of magma.

On Kilauea’s East Rift Zone, GPS stations and tiltmeters continue to show motions consistent with refilling of the deep magmatic reservoir in the broad region between Pu‘u ‘O‘o and Highway 130. This trend has been observed since the end of the 2018 eruption, although there is an indication that this motion has been slowing down during the past couple of weeks.

Sulfur dioxide emission rates on Kilauea’s ERZ and summit remain low, but HVO continues to closely monitor gas emissions in both areas for any changes.

Two earthquakes with three or more felt reports occurred in Hawaii this past week: a magnitude-2.8 quake 4 km (2.5 mi) southwest of Volcano Village at -0.2 km (-0.1 mi) depth at 3:01 a.m. June 6 and a magnitude-2.8 quake 18 km (11.2 mi) east of Honaunau-Napo‘opo‘o at 8 km (5 mi) depth at 11:32 p.m. June 2.

Hazards remain at the lower ERZ and summit of Kilauea. Residents and visitors near the 2018 fissures, lava flows and summit collapse area should heed Hawaii County Civil Defense and Hawaii Volcanoes National Park closures and warnings. Civil Defense advises that lava flows from the 2018 eruption are primarily on private property; people are asked to be respectful and to not enter or park on private property.

The USGS Volcano Alert level for Mauna Loa remains at Normal.

HVO continues to closely monitor Kilauea and Mauna Loa for any signs of increased activity.

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Visit HVO’s website (https://volcanoes.usgs.gov/hvo) for past Volcano Watch articles, Kilauea and Mauna Loa updates, volcano photos, maps, recent earthquake info and more. Call 808-967-8862 for weekly Kilauea updates. Email questions to askHVO@usgs.gov.

Volcano Watch (https://volcanoes.usgs.gov/hvo/hvo_volcano_watch.html) is a weekly article and activity update written by U.S. Geological Survey Hawaiian Volcano Observatory scientists and affiliates.