Hawaiian Volcano Observatory geologists documented newly exposed lava flows and tephra layers in the northwest wall of Kīlauea caldera during a field visit the morning of April 21, 2023. These new exposures will help us better understand Kīlauea's long term eruptive history, which alternates between effusive periods (producing lava flows) and explosive periods (producing tephra such as ash). USGS Photo by K. Lynn.

Three orange-clad geologists from the Hawaiian Volcano Observatory can be seen in this image (in orange, near center of image). During a visit to Halema‘uma‘u crater the morning of April 21, 2023, the geologists collected tephra samples from the Uēkahuna bluff along the northern wall of Kīlauea's summit caldera. Kīlauea has a history of explosive eruptions—the evidence for these events is contained within the many layers exposed along this part of the volcano. USGS image by L. Gallant. 

A morning view of the floor of Halema‘uma‘u, captured by Hawaiian Volcano Observatory geologists during a sampling mission on April 21, 2023. Although the volcano was not erupting when this image was taken, a wispy plume can still be seen rising from the crater floor. Kīlauea summit sulfur dioxide (SO2) emission rates remain low and were most recently measured on April 14 at 110 tonnes per day. USGS image by L. Gallant.

A geologist from the Hawaiian Volcano Observatory (HVO) selects a sampling site on the floor of Halema‘uma‘u crater during the morning of April 21, 2023. The geologist is standing near the eastern rim of the lava lake that was active in the western portion of Halema‘uma‘u crater during the January–March, 2023, eruption. The mound next to the geologist is a spatter rampart; spatter ramparts form when bits of molten lava travel through the air and accumulate on the ground surface, forming a mound-like feature. Crews that visit these dynamic locations have extensive training and wear specialized personal protective equipment, such as helmets and gas masks, to keep them safe. USGS image by L. Gallant.