Hawai‘i Island Volcano Activity Updates: Aug. 18–31, 2017

Kīlauea Caldera from HVO observation tower. Aug. 31, 2017. USGS/HVO image.

Aug. 25–31, 2017

This past week, Hawa‘i Island’s Kīlauea Volcano summit lava lake level fluctuated in concert with summit inflation and deflation, ranging about 105 to 125 feet 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. The 61g flows do not pose an immediate threat to nearby communities.

Widening cracks and slumping on the Kamokuna lava delta indicate its instability and potential for collapse.

Mauna Loa is not erupting.

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.

No significant changes in volcanic gas emissions were measured.

During the last week, small-magnitude earthquakes continued to occur beneath the volcano, primarily in the south caldera and upper Southwest Rift Zone, at depths less than 3 miles. Additional deeper events (3 to 8 miles) occurred beneath the upper west and southeast flanks of the volcano.

One earthquake with three or more felt reports occurred on the Island of Hawaiʻi during the past week: on Aug. 29, 2017, at 3:52 p.m. HST, a magnitude-3.8 earthquake located 7 miles beneath Hawaiian Ocean View Estates.

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.

Aug. 18 –24, 2017

During this week, Kīlauea Volcano’s summit lava lake level fluctuated in concert with summit inflation and deflation, ranging about 115 to140 feet 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 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. USGS/HVO image.

On Aug. 19, a short-lived breakout about 400 feet 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.

During the week, small-magnitude earthquakes continued to occur beneath the volcano, primarily in the south caldera and upper Southwest Rift Zone, at depths less than 3 miles.

Additional deeper events (3 to 8 miles) occurred beneath the upper west and southeast flanks of the volcano.

One earthquake with three or more felt reports occurred in the Hawaiian Islands during the past week: on Aug.18, at 8:35 p.m. HST, a magnitude-4.1 earthquake located 66 miles northeast of Hawaiian Beaches and 19 miles deep.

The Kīlauea Volcano Activity Update is written by U.S. Geological Survey Hawaiian Volcano Observatory scientists and affiliates.

Call for summary updates at (808) 967-8862 (Kīlauea) or (808) 967-8866 (Mauna Loa); email questions to askHVO@usgs.gov.