Number of Vents Spewing Lava Within Halemaʻumaʻu Crater Drops to 1

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The number of vents spewing lava within the Halemaʻumaʻu crater has reduced to one.

Kīlauea volcano continues to erupt as of Friday, Oct. 8, 2021. Lava is currently erupting from a single vent in the western wall of the crater, to which all lava is confined within. Seismicity and volcanic gas emission rates remain elevated.

The previously active vent in the south part of the lake is no longer visible.

On the morning of October 8, 2021, HVO scientists completed a routine helicopter overflight of the ongoing eruption within Halema‘uma‘u at the summit of Kīlauea. This overview photo of the lava lake was captured from the northeast, with the erupting western fissure in the right of the frame, and a number of islands from the December 2020–May 2021 lava lake visible in the center. USGS image.

The volcano began erupting on Sept. 29, 2021. USGS Hawaiian Volcano Observatory (HVO) reported several vents fountaining lava into the lava lake. Over the past week, the number of vents has dwindled down to one, located on the west wall, which has been the most actively flowing lava into the lava lake since the eruption began.

Lava fountains from the vent have sustained heights of about 39 feet, according to HVO. The western end of the lake shows a maximum elevation of approximately 2,549 feet above sea level, which is an increase of about 7 feet over the past 24 hours and a total increase of about 1,12 feet since lava emerged last week.


According to HVO, the lava lake is above the base of the vent and the fountain has built a spatter rampart around with an opening to the east. The fountain is feeding lava to the lake by a flow through the rampart opening.

The central island and several of the smaller eastern islets from the 2020 lava lake are still above the lake surface along with an island of the 2020 western vent rampart in the northwest part of the lake. The lava lake is not level across its surface due to the location of the vent in the western end. Areas closer to the vent are about 3-7 feet higher in elevation compared to the north and south part of the lake and 23 feet higher than the east end of the lava lake.

Active lava and crustal foundering is now mainly focused on the western part of the lava lake.

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.


Sulfur dioxide (SO2) emission rates remain high, with a measured emission rate of approximately 4,700 tonnes per day on Oct. 7, 2021-down from 7,000 tonnes per day yesterday. Seismicity remains elevated but stable. Summit tiltmeters continue to record deflationary tilt.

In this overflight photo of the Halema‘uma‘u lava lake, captured on October 8, 2021 and looking from the northeast, two western fissures are visible: one inactive from the December 2020–May 2021 Kīlauea summit eruption (center), and another actively feeding lava into the lake at this time (upper-right). The older fissure is is being partially overlapped by short lava flows, but it has not been completely drowned because field measurements show that it is floating within the lake. The presently erupting fissure has formed a horseshoe-shaped spatter cone around its source. USGS image. 

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 early 2008.

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