Images

Map of Yellowstone National Park showing the location of major travertine deposits. The green dashed line is the outline of Yellowstone Caldera and red lines are major paved roads.

Travertine sample from the Hillside Springs Group in Upper Geyser Basin, sampled under permit YELL-2020-SCI-8030. (Left) Cut and polished sample slab showing the different layers of travertine; dashed circles indicate where subsamples were taken for geochronology analysis.

On Thursday, April 22, HVO scientists observed the ongoing eruption at the Kīlauea summit from the south rim of Halema‘uma‘u. This photo shows the active western portion of the lava lake, which appears to be in the process of shrinking again, with its northeast (upper-right) and southwest (lower-left) ends crusting over substantially.

A telephoto view of the west vent and lava lake inlet within Halema‘uma‘u crater at the summit of Kīlauea. Lava erupting from the west vent (upper left) continues to feed into the active lava lake through a wide inlet near the base of the cone (center right).

Lava continues to erupt from the west vent within Halema‘uma‘u crater and feed the active lava lake at Kīlauea summit. Volcanic gas emissions from the west vent (lower left) remain elevated and were last measured on April 14 at about 950 t/d.

A telephoto view of the southern lava lake crust and Halema‘uma‘u crater wall at the summit of Kīlauea. Many rockfalls from the steep and unstable crater walls of Halema‘uma‘u have deposited large boulders onto the stagnant lava surface over the past few months. This photo was taken from the west rim of Halema‘uma‘u looking southeast. USGS photo taken by L.

A telephoto view of the northwestern point of the main island within Halema‘uma‘u crater, at Kīlauea summit. A rockfall scar (center left) remains after a small collapse of the island was observed by field geologists around 12:43 p.m. HST on April 20, 2021. A sliver of the active lava lake surface is visible at the bottom of this photo.

A view of Halema‘uma‘u crater at the summit of Kīlauea Volcano, Island of Hawai‘i, showing the active western fissure with rising fumes, the active western portion of the lava lake (lighter colored area in the middle of the photo), and the big island within the lava lake (right).

April 20 was the four-month anniversary of Kīlauea's ongoing summit eruption in Halema‘uma‘u. This animated GIF features approximately one thermal image for each day of the eruption and demonstrates eruptive activity over the past four months. At 9:30 p.m.

A helicopter overflight on April 16, 2021, at approximately 12 p.m. HST allowed for aerial visual and thermal imagery to be collected of the eruption within Halema‘uma‘u crater at the summit of Kīlauea Volcano.

An HVO geologist surveys the lava lake from the eastern rim of Halema‘uma‘u Crater, at the summit of Kīlauea. The cliff that covers most of the top half of the photo formed during the collapse events of 2018, and gives a sense of the scale of that event. USGS photo by M. Patrick on April 16, 2021.

A view of the south margin of the perched lava lake in Halema‘uma‘u Crater, at the summit of Kīlauea. This photo was taken from the east rim of the crater, and shows the steep levee containing the lake. USGS photo by M. Patrick.

A view of the lava lake from the east rim of Halema‘uma‘u Crater, at the summit of Kīlauea. The active portion of the lake is present at the far (western) end of the crater. USGS photo by M. Patrick on April 16, 2021.

During a Kīlauea summit helicopter overflight on Friday, April 16, an HVO scientist captured this photo of the erupting western fissure and surrounding lava lake within Halema‘uma‘u. The active western potion of the lava lake, as seen here, measured approximately 300 m (984 ft) from end-to-end at the time. USGS image.

A close-up view of the western fissure within Halema‘uma‘u at the summit of Kīlauea Volcano, Island of Hawai‘i. Lava continues to enter the lava lake from a wide inlet near the base of the western vent (fuming at center right). Crustal foundering is common on the active lava lake surface (center bottom), located on the western side of the crater.

This view from the south rim of Halema‘uma‘u shows the perched lava lake, supplied by lava from the western fissure (upper right portion of photo). The levee surrounding the active lava lake is up to about 5 m (16 ft) high. USGS photo by M. Patrick on April 13, 2021.

A close up view of the inlet at the western margin of the lava lake in Halema‘uma‘u Crater, at the summit of Kīlauea. The lava stream was covered in a thin, flexible crust and was moving at a very slow velocity. USGS photo taken by M. Patrick on April 13, 2021.

Lava continues to erupt from the west vent in Halema‘uma‘u crater at Kīlauea Volcano's summit. This photo of the vent and active western portion of the lava lake was taken around 3:00 p.m. HST from the south rim of Halema‘uma‘u crater. USGS photo taken by K. Lynn on April 9, 2021.

On Friday, lava erupting from the west vent in Halema‘uma‘u crater emerged from a source closer to the vents base (center), a few feet away from the submerged effusive inlet that has been feeding the lava lake for several weeks (lower right).

On Friday afternoon, April 9, lava entered the Halema‘uma‘u lava lake from two sources near the base of the west vent (degassing on left side of the image). This photo was taken around 4:00 p.m. HST from the western rim of Halema‘uma‘u crater, at Kīlauea summit. The lava source closer to the west vent emerged approximately one hour before this photo was taken.

The crusted-over southern shoreline of the lava lake in Halema‘uma‘u at Kīlauea's summit has accumulated talus (rubble) blocks on the surface since it solidified in February. On April 8, 2021, HVO field geologists noted steaming east of the talus (above the rubble in the photo) that was producing hazy viewing conditions. USGS photo by C. Parcheta.