A look at the past year of Kīlauea's summit water lake

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Water was first observed at the summit of Kīlauea Volcano, within Hawai‘i Volcanoes National Park, one year ago. Since then, the body of water has slowly deepened and grown in size. The Hawaiian Volcano Observatory continues to monitor the lake, and have summarized one year of observations. Additional resources are available on the Kīlauea summit water webpage

Kīlauea Volcano remains at alert-level NORMAL and aviation color-code GREEN. Levels of seismicity, deformation, and gas emission remain at background levels.

Animated GIF showing rise of crater lake

ANIMATED GIF: Saturday, July 25, marks the one year anniversary since water was first spotted at the bottom of Halema‘uma‘u, at the summit of Kīlauea. Over the past year, the summit water lake has grown to more than 270 m (885 ft) long and 131 m (430 ft) wide, with a surface area over 2.5 hectares (6 acres). The lake is over 40 m (130 ft) deep with a volume of approximately 480,000 cubic meters (125 million gallons)—equivalent to almost 200 olympic swimming pools. This animated image file (GIF) includes a series of telephoto images in a continuous loop showing the growth of the lake between August 2, 2019 and July 21, 2020, using approximately one image every 2 weeks. The apparent movement of the surrounding ground surface is not real—the shift is caused by slightly different camera angles on different days. (Credit: L. DeSmither, USGS. Public domain.)

Two color photograph's of lake

Comparison of images showing growth of Kīlauea's summit water lake over the past year. The left image, taken on August 2, 2019, shows a small green pond that was approximately 6 ft (2 m) deep. The right image, taken on July 21, 2020, shows a lake more than 130 ft (40 m) deep with shades of tan to brown and a sharp color boundary often cutting across the lake. Hawaiian Volcano Observatory scientists continue to monitor the lake, and Kīlauea's summit. (Credit: USGS. Public domain.)

Color inforgraphic summarizing Kīlauea summit water lake observations


Summit crater lake growth

July 25, 2019 to July 25, 2020

Background image: Panorama that shows the view of Halema‘uma‘u from the northwest caldera rim, and shows much of the caldera floor that subsided during 2018. The water lake is visible at the bottom of Halema‘uma‘u. Kīlauea Iki is in the upper left portion of the photo. USGS photo by M. Patrick on June 30, 2020.

Map of the Island of Hawai‘i showing the area that is Kīlauea Volcano, with the summit, East Rift Zone, and Southwest Rift Zone labelled.

• During the 2018 lower East Rift Zone eruption, Kīlauea Volcano’s summit collapsed, forming a pit more than 1600 ft (500 meters) deep within the caldera.

• On July 25, 2019, ponded water was first observed at the base of the collapse pit.

• U.S. Geological Survey Hawaiian Volcano Observatory (HVO) scientists are tracking and characterizing the lake, which continues to grow as hot groundwater seeps in.

• The summit of Kīlauea, located within Hawai‘i Volcanoes National Park and home to Hawaiian volcano deity Pele, is a dynamic volcanic landscape monitored by HVO.

July 2020 Lake Statistics

Volume: over 125 million gallons (480,000 cubic meters); equivalent to almost 200 olympic swimming pools

Dimensions: over 885 by 430 ft (270 by 131 meters)

Area: over 6 acres  (2.5 hectares)

Depth: over 130 ft (40 meters); ~2.5 ft  (0.75 meters) of rise each week since first seen on July 25, 2019

Monitoring the lake

Webcam imagery: Visual and thermal cameras track lake-surface color and temperature

Measuring lake level: Routine laser rangefinder measurements

Water sampling: Two dedicated water-sampling missions via unoccupied aircraft systems: October 2019 and January 2020

Image of measuring the lake level: Clear weather allowed another measurement of Kīlauea's summit water pond to be made on April 6, 2020. Results show continued slow rise of the water level in Halema‘uma‘u Crater. No major changes were observed. Note the former HVO observation tower can be seen above the geologist's helmet. USGS photo.

Image of water sample: The purpose of the UAS flights was to collect water samples and gas data to assess ongoing volcanic hazards. HVO's work in a culturally sensitive area closed to the general public was done with permission of Hawai‘i Volcanoes National Park. After a sample was collected, HVO team members transferred water from the sampling device to plastic bottles. The scientists wore protective gear, including hardhats in case of rockfall hazards near the crater rim, as well as aprons, goggles, and gloves to shield them from the hot, acidic water. USGS photo by S. Warren on January 17, 2020.

Lake image taken on September 27, 2019: Telephoto view of the water pond within Halema‘uma‘u at Kīlauea's summit. Little steam was emanating from the hot crater lake, likely as a result of the warm air temperature on this sunny day. USGS photo by K. Mulliken, 09-27-2019.

Lake image taken on June 30, 2020: No significant changes were observed during today's visit to monitor Kīlauea's summit water lake. The lake surface exhibited some interesting color variations today, but within the range of those previously observed. The sharp color boundary between tan and brown zones has been common. Today, a wedge-shaped, slightly greenish zone was present in the west portion of the lake (towards bottom of image). Laser rangefinder measurements indicate that the lake level continues to slowly rise. USGS photo by M. Patrick.

Lake image taken on May 29, 2020: During today's overflight of Kīlauea summit, both thermal and visual cameras were used to characterize activity. Comparing thermal (left) to visual (right) images of nearly the same view, you can see that the growing crater lake at Kīlauea's summit remains hot. Steam emanates from the lake surface in the visual image on the right, and the yellow and red colors in the thermal image indicate that the lake has a hotter surface temperature relative to the rocks and rubble around it. The lake isn't the only hot feature within Halema‘uma‘u. Fumaroles on the crater wall, which stand out as white areas indicating alteration in the visual image, have small zones of elevated temperature in the thermal image. USGS images by M. Patrick (left) and K. Mulliken (right).

Lake color, chemistry, and temperature:

Color: Color is variable, ranging from green to yellow to orange to dark brown; likely influenced by water influx

Chemistry: Water is moderately acidic, with a pH of ~4 (similar to fruit juice); chemistry indicates ongoing reactions between lake water, volcanic gases, and surrounding basaltic rocks

Temperature: Thermal cameras and water sampling indicate that the lake surface is consistently around 158–185 degrees Fahrenheit (70–85 degrees Celsius)

Tracking lake rise

Chart showing the lake-level data from August 2019, when the lake was 2 yards (2 meters) deep, to July 2020, when the lake was 40 yards (40 meters) deep.

Lake image taken on July 7, 2020: No significant changes were observed during today's visit to monitor Kīlauea's summit water lake. USGS photo by M. Patrick.

Lake image taken on August 27, 2019: Clear weather today provided ideal conditions for HVO's observations of the water pond at the bottom of Halema‘uma‘u. Routine laser rangefinder measurements indicate that the pond continues to rise. The rate at which the water is rising is estimated to be less than one meter (yard) per week, so day to day changes in the pond dimensions are subtle. USGS photo by M. Patrick.

Caldera cross-section (west to east) showing the pre- and post-2018 caldera floor, with the presumed local water table.

Kīlauea summit aerial map made on May 29, 2020: The May 29 overflight provided updated aerial photographs of Kīlauea summit, covering the caldera floor and showing the current size of the water lake in Halema‘uma‘u crater. The water lake has a surface area of approximately 25,000 square meters (6.2 acres), which is more than double the area measured in late December, when it was 11,000 square meters (2.7 acres). The water lake is still smaller in area than the former Halema‘uma‘u lava lake, which was approximately 48,000 square meters (11.9 acres) just before it drained in May 2018. The label "downdropped block" shows the large portion of the caldera floor that subsided, along with the Halema‘uma‘u region, during the 2018 eruption. The surrounding area is shown by a 2018 satellite image.


Kīlauea is currently at volcano alert-level NORMAL and aviation color code GREEN. Levels of seismicity, deformation, and gas emission remain at background levels following the 2018 activity. At this time, there is no indication of an impending eruption at Kīlauea’s summit.

Magma and water interactions can be explosive so HVO closely monitors multiple data streams on Kīlauea Volcano including ground deformation, seismicity, volcanic gases, and imagery.

Subscribe to the Volcano Notification Service to receive volcano activity notifications: volcanoes.usgs.gov/vns2/

Visit https://volcanoes.usgs.gov/volcanoes/kilauea/summit_water_resources to learn more about Kīlauea’s summit crater lake. 

Visit volcanoes.usgs.gov/hvo to learn more about Kīlauea and other active volcanoes in Hawaii monitored by the USGS Hawaiian Volcano Observatory.

U.S. Department of the Interior

U.S. Geological Survey

Hawaiian Volcano Observatory

Volcano Hazards Program

July 25, 2020; K. Mulliken

(Credit: USGS. Public domain.)