Collapses within Halema‘uma‘u’s lava lake are common, especially when the lake level drops and the new veneer (coating of lava) peels from the walls. Recently, there were two larger collapses that removed thin slices of the older lithic wall, and slightly changed the size and geometry of the lava lake. The collapses were not large enough to produce explosive events, but did trigger seismic signals and lake surface agitation along with spattering for tens of minutes. This photo from a Halema‘uma‘u time-lapse camera was taken on December 12 and shows the approximate areas (dashed yellow lines) that collapsed on December 5 at 4:40 am (right), and December 7 at 6:56 pm (left). Photo taken Tuesday, December 12, 2017 courtesy of U.S. Geological Survey

An image from a Halema‘uma‘u time-lapse camera taken on December 5 at 4:41 am, just after the collapse. The portion of the rim that fell into the Halema‘uma‘u lava lake triggered intense spattering on the lake margin where the material impacted the lake. The collapse also agitated the entire surface of the lava lake, breaking up the crustal plates into many small ones. Photo taken Tuesday, December 5, 2017 courtesy of U.S. Geological Survey

Time-lapse thermal image movie of Halemaumau Overlook Vent. December 14-21, 2017. Images courtesy of USGS/HVO

Time-lapse movie of Halemaumau Overlook Vent. December 14-21, 2017. Images courtesy of USGS/HVO

Time-lapse movie of Halemaʻumaʻu Overlook Vent from Hawaiian Volcano Observatory. December 14-21, 2017. Images courtesy of USGS/HVO

Time-lapse movie of KÄ«lauea Caldera from Hawaiian Volcano Observatory. December 14-21, 2017. Images courtesy of USGS/HVO

Time-lapse movie of Halemaumau Crater looking Southwest. December 14-21, 2017. Images courtesy of Hawaii Volcanoes National Park

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

This past week, Kīlauea Volcano’s summit lava lake level fluctuated with summit inflation and deflation and ranged about 30-44 m (98–144 ft) below the vent rim. On the East Rift Zone, the 61g flow remained active, with scattered breakouts downslope of Pu‘u ‘Ō‘ō, but not at the ocean entry. The 61g flows do not pose an immediate threat to nearby communities.

Mauna Loa is not erupting. During the past week, small-magnitude earthquakes continued to occur beneath the volcano. Shallow seismicity was concentrated beneath the summit caldera and upper Southwest Rift Zone at depths less than 5 km (3 miles). Additional deeper seismicity (5-20 km or 3-12 miles) was scattered beneath the southeast flank of the volcano. Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) measurements continue to show 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. Overall rates of deformation and seismicity have decreased towards long-term background levels. Similar decreases have occurred in the past during the ongoing period of unrest that started in 2014; it is unknown if these low rates will persist or if they will pick up again in the near future.
No earthquakes were reported felt in the Hawaiian islands during the past week.