USGS webcam view of the west vent in Halemaʻumaʻu and the lava lake, from the northwest rim of the caldera, looking south

UPDATE – (11:30 a.m. HST on Wednesday, September 21)

• Following Tuesday’s sudden, short-lived increase in activity, the summit eruption of Kīlauea Volcano continued on Wednesday. All activity remains confined to the crater floor of Halemaʻumaʻu inside Hawaiʻi Volcanoes National Park, with no significant changes in areas outside of the summit.
• After a large increase in inflationary tilt and a seismic swarm of more than 80 earthquakes on Tuesday afternoon, extensive lava breakouts began occurring along the western and northern parts of the crater floor. At the same time, a drop in the crater floor and the active part of the lava lake was observed.
• The active part of the lava lake dropped by 10 meters (33 feet) and other parts of the crater floor dropped by several meters.
• No unusual activity has been noted along the East Rift Zone or Southwest Rift Zone.

From the USGS Hawaiian Volcano Observatory on Wednesday morning:

Activity Summary: The summit eruption of Kīlauea Volcano, within Halemaʻumaʻu crater, continued over the past 24 hours. Extensive breakouts have occurred along the western and northern parts of the crater floor within this time. These breakouts coincided with a drop in the crater floor and the active part of the lava lake. All activity remains confined to the crater floor of Halemaʻumaʻu with no significant changes in areas outside of the summit.

Halemaʻumaʻu Lava Lake Observations: Eruption of lava from the western vent into the active lava lake and onto the crater floor continued over the past 24 hours with extensive breakouts in the western and northern parts of the crater floor starting at 4:00 PM HST on September 20, 2022. The active part of the lava lake dropped by 10 meters (33 feet) and other parts of the crater floor dropped by several meters (several yards). Overflight measurements from September 12, 2022, indicated that the crater floor had seen a total rise of about 143 meters (469 feet), and that 111 million cubic meters (29.2 billion gallons) of lava had been effused since the beginning of this eruption on September 29, 2021.

Summit Observations: Summit tiltmeters recorded a large increase in inflationary tilt of approximately 12 microrads (at UWE) and 1.5 microrads (at SDH) from 3:00 to 4:00 PM, which has remained flat since. This was in association with a summit seismic swarm of more than 80 earthquakes from 3:00 PM to 6:00 PM. Most earthquakes in this swarm occurred approximately 1 mile (1.5 kilometers) beneath Halemaʻumaʻu. The largest recorded earthquake was a magnitude 2.9, with the majority of the earthquakes being less than magnitude 2. Volcanic tremor remains above background levels. A sulfur dioxide (SO2) emission rate of approximately 1055 tonnes per day (t/d) was measured on September 20, 2022.

Rift Zone Observations: No unusual activity has been noted along the East Rift Zone or Southwest Rift Zone; low rates of ground deformation and seismicity continue along both. Measurements from continuous gas monitoring stations downwind of Puʻuʻōʻō in the middle East Rift Zone remain below detection limits for SO2, indicating that SO2 emissions from Puʻuʻōʻō are negligible.

Hazard Analysis: This eruption at Kīlauea’s summit is occurring within a closed area of Hawaiʻi Volcanoes National Park. High levels of volcanic gas are the primary hazard of concern, as this hazard can have far-reaching effects downwind. Large amounts of volcanic gas—primarily water vapor (H2O), carbon dioxide (CO2), and sulfur dioxide (SO2)—are continuously released during eruptions of Kīlauea Volcano. As SO2 is released from the summit, it reacts in the atmosphere to create the visible haze known as vog (volcanic smog) that has been observed downwind of Kīlauea. Vog creates the potential for airborne health hazards to residents and visitors, damages agricultural crops and other plants, and affects livestock.