Fourth phase of Kīlauea middle East Rift Zone eruption no longer active

The latest and largest phase so far of the middle East Rift Zone eruption of Kīlauea volcano on the Big Island seems to be finished as its large channels of lava extending from a fissure system just west of Nāpau Crater and lava falls cascading onto the crater’s floor had crusted over completely by between 9 and 10 p.m. Thursday.

Strong glow from the vent also decreased significantly by about 2:30 a.m. today and continued is dimming trend until daylight.

The eruption appeared to be waning as of 6 a.m.

Hawaiian Volcano Observatory field crews reported minor spattering, lava flows and small fountains erupting from one of the earlier western fissures as of 8:50 a.m. today, but it ended by 10 a.m. Tremor also remains low, indicating eruptive activity is minimal.

Before its pause Friday moring, the eruption had covered a total of more than 156 acres of Nāpau Crater and areas to the west since it started between 9 and 10 p.m. Sunday.

Sulfur dioxide emission rates measured Thursday were 30,000 tonnes per day for the new vent that opened that afternoon. Comparatively, the most recent SO2 rate measured at the summit was 60 tonnes per day on Tuesday.  

High levels of volcanic gas — primarily water vapor and SO2 — continue to be one of the largest hazards of the eruption and can have far-reaching effects downwind.

As sulfur dioxide is released from lava, it reacts in the atmosphere to create visible haze known as vog, or volcanic smog. Vog creates the potential for airborne health hazards to people, animals and plants.

“Still rather steamy on camera,” pointed out Shawn Noe on an 8:38 a.m. update from the Hawaiian Volcano Observatory on Facebook that inclulded a webcam GIF of the eruption location that indeed showed plumes of gas still eminating from the area of the vents despite there being no active lava flowing at the time.

Communities such as Ocean View, Hoʻōpūloa, Kēōkea and others along the west and southwest coasts of the island were the worst affected as of Friday by the volcanic gasses from the eruption.

PurpleAir sensors in several of those locations showed levels of particulates in the air to be in the upper 80s to lower 90s, which could make members of sensitive groups experience adverse health effects if exposed for 24 hours or longer.

“The air quality down in [Hawaiian Ocean View] Ranchos is over 60 and we are feeling it [tonight],” said Karen Pucci replying to a Facebook post Wednesday by Tudie Stewart-Ryley sharing about the air quality in nearby Ocean View measured by another app.

“Especially anyone with asthma or any kind of respiratory issues at all are definitely going to feel it,” answered back Stewart-Ryley.

Vog information can be found here. For more information about other gas hazards, click here.

Shallow earthquake counts remain low in the middle East Rift Zone, with about 10 recorded during the past day. Tremor close to the eruption site also decreased significantly late yesterday and early this morning as eruptive activity died down by early this morning.

Tiltmeters in the middle East Rift still show no significant shallow deformation, but GPS instruments show continued inflation at deeper levels beneath the area between Maunaulu and Nāpau Crater.

The eruption is confined within a remote and closed wilderness area of Hawai’i Volcanoes National Park between Makaopuhi Crater and Puʻuʻōʻō.

There are no indications of any changes in the Southwest Rift Zone or farther downrift in the lower East Rift Zone.

Renewed unrest or eruptions are possible in the area of the paused eruption site and could occur with little to no warning.

The Volcano Alert Level for Kīlauea remains at Watch and its Aviation Color Code at Orange.

Each phase of the current eruption has increased in volume compared to the prior one so far; therefore, new phases, if there are any, might continue this trend.

Multi-day fissure eruptions are not unusual, and this activity appears to be linked to the continuing supply of magma from the summit. 

Six small, shallow earthquakes were detected beneath the Kīlauea summit region during past 24 hours.

The tiltmeter at Uēkahuna transitioned sharply from deflation to minor inflation at about 4:15 p.m. Thursday; however, the summit tiltmeter at Sandhill continues to record strong deflation.

This pattern suggests only the deeper, southern summit magma body is continuing to supply magma to the middle East Rift Zone. 

Shallow magma movement and eruptions can produce minor to severe ground fractures and subsidence features that can affect the landscape, human activity and infrastructure.

These ground cracks can continue to widen and offset as magma migration continues, have unstable overhanging edges and should be avoided. 

Existing fissures also can reactivate at any time.

For discussions about all possible Kīlauea hazards, click here.

The Hawaiian Volcano Observatory is closely monitoring the middle East Rift Zone and is in contact with Hawai‘i Volcanoes National Park and Hawai‘i County Civil Defense.

Visit the Hawaiʻi Volcanoes National Park website for visitor information.

Big Island Now news reporter Nathan Christophel contributed to this story.