Lava Lake Rises 3 Feet Over 24 Hours, HVO Reports

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Over the past 24 hours, the lava lake level within Halemaʻumaʻu crater has risen approximately 3 feet, according to a daily report from the US Geological Survey (USGS) Hawaiian Volcano Observatory (HVO) on Tuesday, Oct. 5, 2021.

Kīlauea volcano began erupting on Sept. 29, 2021. Lava continues to erupt from multiple vents along the floor and western wall of the Halemaʻumaʻu crater. The lava lake has risen to the base of the west vent, around which a spatter rampart is being built.

A brief gap in the fume provides a clear view of the fountaining at the western vent in Halema‘uma‘u crater, at the summit of Kīlauea. Sulfur dioxide (SO2) emission rates remain elevated and were measured at approximately 7,000 tonnes per day on October 4. USGS photo taken by M. Patrick from the southern crater rim on October 4, 2021.

According to the daily report, the west vent continues to be the most vigorous source, with sustained lava fountain heights of 43 to 52 feet, and bursts up to 66 feet observed.

Other vents continue to be active in the southern part of the lake, with sustained lava fountain heights of about 3 to 16 feet. Due to the location of vents, the lava lake is not level across its surface; areas closer to vents are higher in elevation.


On Monday evening, Oct. 4, 2021, the west and south ends of the lake were about 3 to 7 feet higher than the east and north ends.

The north and east boundaries of the lava lake are separated from Halemaʻumaʻu crater wall by narrow ledges, approximately 66 feet, that are lower in elevation than the active portion of the lava lake surface; the north, east, and south sides of the lava lake are perched several yards above this surrounding ledge.

Localized and discontinuous crustal foundering continues, which is a process by which cool lava crust on the surface of the lava lake is overridden by less-dense liquid from below causing the crust to sink into the underlying lake lava.


Sulfur dioxide (SO2) emission rates remain high, with preliminary measurements of approximately 7,000 – 9,000 tonnes per day on Oct. 4, 2021. Seismicity remains elevated but stable. Summit tiltmeters continue to record deflationary tilt.

No unusual activity has been noted in the Kīlauea East Rift Zone. Ground deformation motion suggests that the upper East Rift Zone—between the summit and Puʻuʻōʻo—has been steadily refilling with magma over the past year. SO2 and hydrogen sulfide (H2S) emissions from Puʻuʻōʻō were below instrumental detection levels when last measured on Jan. 7, 2021.

This new eruption at Kīlauea’s summit is occurring within a closed area of Hawai’i Volcanoes National Park. Therefore, 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. For more information on gas hazards at the summit of Kīlauea, click here. Vog information can be found here

Additional hazards include Pele’s hair and other lightweight volcanic glass fragments from the lava fountains that will fall downwind of the fissure vents and dust the ground within a few hundred yards of the vent(s). Strong winds may waft lighter particles to greater distances. Residents should minimize exposure to these volcanic particles, which can cause skin and eye irritation.

Other significant hazards also remain around Kīlauea caldera from Halemaʻumaʻu crater wall instability, ground cracking, and rockfalls that can be enhanced by earthquakes within the area closed to the public. This underscores the extremely hazardous nature of Kīlauea caldera rim surrounding Halemaʻumaʻu crater, an area that has been closed to the public since late 2007.

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