Video courtesy of Tropical Visions Video with air transportation by Paradise Helicopters.

On Saturday, August 19 at 04:10 HST a breakout that started 120 m (394 ft) up-slope of the ocean entry, began to spill over the sea cliff and onto the delta. The lava fall was located to the west of the ramp (tubed-over firehose), and produced a small ‘a‘ā flow on the western portion of the delta. This breakout was short-lived and appeared to have died by 1:30 pm HST, lasting about 9.5 hours. The photo pictured above was taken at 6:40 am HST, showing the lava fall and some faint activity of the ‘a‘ā flows on the far side of the delta. Many cracks remain and continue to widen on the delta, although they are more difficult to see in the early morning light. Photo taken Saturday, August 19, 2017 courtesy of USGS/HVO

At 9:35 pm HST on August 19, there was a large littoral explosion near the front of the delta (left). Another smaller explosion was seen 5 minutes later. These explosions are typically caused by mixing of cool sea water and hot lava. The August 19 explosions were not followed by obvious delta subsidence or collapse, something we have seen in the past. Photo taken Saturday, August 19, 2017 courtesy of USGS/HVO

A telephoto image of the spatter deposit produced by the August 19 littoral explosions at the lava delta. When ejected, the spatter was thrown much higher than the height of the sea cliff which is approximately 28 m (92 ft). The flying debris is just one of the many hazards at an ocean entry. Photo taken Monday, August 21, 2017 courtesy of USGS/HVO

Time-lapse thermal image movie of Halemaumau Overlook Vent. August 17-24, 2017. Images courtesy of USGS/HVO

Time-lapse movie of Halemaumau Overlook Vent. August 17-24, 2017. Images courtesy of USGS/HVO

Time-lapse movie of Halemaʻumaʻu Overlook Vent from Hawaiian Volcano Observatory. August 17-24, 2017. Images courtesy of USGS/HVO

Time-lapse movie of KÄ«lauea Caldera from Hawaiian Volcano Observatory. August 17-24, 2017. Images courtesy of USGS/HVO

Time-lapse movie of Halemaumau Crater looking Southwest. August 17-24, 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 in concert with summit inflation and deflation, ranging about 35–43 m (115–140 ft) below the vent rim. On the East Rift Zone, the 61g flow remained active, with lava entering the ocean near Kamokuna and surface breakouts downslope of Pu‘u ‘Ō‘ō. Widening cracks and slumping on the Kamokuna lava delta indicate its instability and potential for collapse. On August 19, a short-lived breakout about 120 m (400 ft) inland of the delta formed a cascade of lava over the sea cliff and onto the western delta surface; this activity lasted less than 10 hours. 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, primarily in the south caldera and upper Southwest Rift Zone, at depths less than 5 km (3 mi). Additional deeper events (5–13 km, or 3–8 mi) occurred beneath the upper west and southeast flanks of the volcano. GPS 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.

One earthquake with three or more felt reports occurred in the Hawaiian Islands during the past week: On August 18, 2017, at 8:35 p.m. HST, a magnitude-4.1 earthquake located 107 km (66 mi) northeast of Hawaiian Beaches and 30 km (19 mi) deep.

Time-lapse movie of Pu’u ‘O’o Crater. August 17-24, 2017. Images courtesy of USGS/HVO

Time-lapse image movie from a research camera positioned on Holei Pali, looking east towards Lava Flow 61G and Kalapana. August 17-24, 2017. Images courtesy of USGS/HVO

This map shows recent changes to KÄ«lauea’s East Rift Zone lava flow field. The area of the active flow field as of August 9 is shown in pink, while widening and advancement of the active flow as of August 20 is shown in red. Older PuÊ»u ʻŌʻō lava flows (1983–2016) are shown in gray. The yellow line is the trace of the active lava tube.
The blue lines over the PuÊ»u ʻŌʻō flow field are steepest-descent paths calculated from a 2013 digital elevation model (DEM), while the blue lines on the rest of the map are steepest-descent paths calculated from a 1983 DEM (for calculation details, see http://pubs.usgs.gov/of/2007/1264/). Steepest-descent path analysis is based on the assumption that the DEM perfectly represents the earth’s surface. DEMs, however, are not perfect, so the blue lines on this map can be used to infer only approximate flow paths. The base map is a partly transparent 1:24,000-scale USGS digital topographic map draped over the 1983 10-m digital elevation model (DEM).