“Dimples” in the Pele’s hair that has accumulated on the rim of Halema‘uma‘u are evidence of ballistic impacts during today’s rockfall-triggered explosion in KÄ«lauea Volcano’s summit lava lake. Spatter (fragments of molten lava) blasted from the lava lake landed all around HVO’s thermal camera (HTcam) that monitors lake activity. Fortunately, the camera escaped damage, so thermal images of the lava lake can still be viewed on HVO’s webcam page (https://volcanoes.usgs.gov/hvo/webcam.html?webcam=HTcam). Photo taken Friday, January 19, 2018 courtesy of U.S. Geological Survey

Spatter up to about 30 cm (11.8 in) in size was hurled onto the rim of Halema‘uma‘u during today’s explosive events. Some fragments were thrown or blown farther downwind, reaching as far as the closed section of Crater Rim Drive in Hawai‘i Volcanoes National Park. The boot of an HVO scientist, who entered the area to check on HVO’s webcameras, is shown here for scale. Photo taken Friday, January 19, 2018 courtesy of U.S. Geological Survey

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This video shows a rockfall and subsequent explosion that occurred at 7:03 a.m. HST Friday (Jan 19) within the “Overlook crater” at the summit of KÄ«lauea. This collapse was followed by a smaller rockfall at 7:07 a.m. (not shown in video). Rocks falling into the lava lake agitated the lake surface and caused the lake to “slosh” back-and-forth for at least 15 minutes following the collapse. Explosive events triggered by rockfalls, like those this morning, occur with no warning and are one of the reasons why the Halema‘uma‘u crater rim area remains closed to the public. Fallout from today’s explosion would have resulted in serious injury to anyone on the impacted crater rim.

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Time-lapse thermal image movie of Halemaumau Overlook Vent. January 18-25, 2018. Images courtesy of USGS/HVO

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Time-lapse movie of Halemaumau Overlook Vent. January 18-25, 2018. Images courtesy of USGS/HVO

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Time-lapse movie of Halemaʻumaʻu Overlook Vent from Hawaii-an Volcano Observatory. January 18-25, 2018. Images courtesy of USGS/HVO

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Time-lapse movie of KÄ«lauea Caldera from Hawaiian Volcano Observatory. January 18-25, 2018. Images courtesy of USGS/HVO

(Activity updates are written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.)

This past week, KÄ«lauea Volcano’s summit lava lake level fluctuated with summit inflation and deflation, ranging about 30.5–39 m (100–128 ft) below the vent rim. On the East Rift Zone, the 61g lava flow remained active downslope of Pu‘u ‘Ō‘ō, with scattered breakouts on the pali and coastal plain, but no ocean entry. The 61g flows do not pose an immediate threat to nearby communities.

Mauna Loa Volcano is not erupting. Rates of deformation and seismicity remain above long-term background levels, but rates in the past few months have decreased compared to rates of the past year. Similar decreases have occurred during the ongoing period of unrest; it is uncertain if these lower rates will persist or pick up again in the near future. Small-magnitude earthquakes occurred beneath the summit caldera and upper Southwest Rift Zone at depths less than 5 km (3 mi). A few deeper earthquakes were scattered beneath the volcano’s southeast flank at depths less than 13 km (8 mi). GPS and InSAR measurements continue to show slow deformation related to inflation of a magma reservoir beneath the summit and upper Southwest Rift Zone. No significant changes in volcanic gas emissions were measured.

Two earthquakes with three or more felt reports occurred in Hawaii this past week: A magnitude-3.6 earthquake 42 km (26 mi) northeast of Kapaʻau at 42 km (29 mi) depth on January 24 at 3:41 a.m. HST, and a magnitude-2.5 earthquake 2 km (1 mi) east of Leilani Estates at 2 km (1 mi) depth on January 19 at 7:26 a.m. HST.

Please visit the HVO website (https://volcanoes.usgs.gov/hvo) for past Volcano Watch articles, KÄ«lauea daily eruption updates, Mauna Loa weekly updates, volcano photos, maps, recent earthquakes info, and more. Call for summary updates at 808-967-8862 (KÄ«lauea) or 808-967-8866 (Mauna Loa). Email questions to askHVO@usgs.gov.

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Time-lapse movie of Pu’u ‘O’o Crater. January 18-25, 2018. Images courtesy of USGS/HVO

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Time-lapse movie from a camera positioned on the southeast flank of Puʻu ʻŌʻō, looking toward the active flow advancing to the southeast. The breakout point is at the left edge of the image, and the mid-field skyline at the right is roughly coincident with the top of the pali. January 18-25, 2018. Images courtesy of USGS/HVO

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Time-lapse image movie from a research camera positioned on Holei Pali, looking east towards Lava Flow 61G and Kalapana. January 18-25, 2018. Images courtesy of USGS/HVO