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Kīlauea Report: New Outlets From West Vent

4:16 AM · Nov 17, 2021

Since Kīlauea’s most recent eruption began on September 29th, 2021, lava has filled the then-112 acre or 45 hectare Halemaʻumaʻu crater by 197 feet or 60 meters, bringing the lava lake and West Vent into direct public view within Hawaiʻi Volcanoes National Park. Most recently, the roughly 80-foot or 25-meter high cone, floating above the single vent on the rising lava lake, has sprung two new lava outlets from its base near the western crater wall. These feed new smaller streams of lava around the cone and down into the lake, one on each side of the still-active original entry point that has been fluctuating in vigor. Just last week, its output slowed enough that the active lava lake surface almost entirely crusted over, before returning to its previous stronger levels after less than a day. The area of visible active lava has decreased in the past few weeks to 17 acres or 7 hectares, now covering only 11% of the innermost crater floor, and yet the eruption continues to add to the mass of lava beneath the hardened crust making up the other 89% of its area, lifting it up and oozing out beyond its farthest edges. Some of these peripheral ooze-up flows are now slowly covering a growing area on the lowest down-dropped block to the north. While time-lapses show the dramatic filling of the crater over the past month and a half, the combined output of this eruption and the previous 5-month eruption only adds up to about 8.5% of the volume lost during the 2018 summit collapse. Unlike 2018, there are no signs of further magma movement from the summit into either rift zone. Instead, the September 2021 eruption seems to be following the pattern of the last summit eruption beginning in December 2020, especially in its output rates, active lava area, and total volume erupted, though it has currently produced 15% less lava over the same duration -- in other words, smaller than the last eruption. Gas emissions remain in the ~2000-5000 tonnes per day range, creating persistent vog for downwind communities as the eruption’s main hazard. The new outlets from the base of the West Vent cone mark the latest evolution of its eruptive style, from low fountaining with episodic bursts during its first few weeks to low roiling and spatter bursts during the last two weeks, perhaps owing to its submergence under the filling lake since October 3rd. The spatter cone surrounding the vent has not remained fixed to the crater wall like the two vents during the previous eruption, but rather has also been rising, carried upwards by the filling lava lake. The original spillway from the horseshoe-shaped cone gradually crusted over and constricted during low-effusion periods, eventually restricting the output and apparently leading to the appearance of the new outlets, in the latest small changes within the overall progression of the eruption. -- Join our special live video review of Kīlauea’s ongoing eruption at 5pm Hawaiʻi time weekly on Thursdays! To support our productions please like, share and subscribe! Mahalo! #Kilauea2021 #KilaueaErupts USGS Images: 1. A view of the active west vent within Halema‘uma‘u crater, at the summit of Kīlauea, on November 15, 2021. A new flow has developed on the south side of the west vent cone (right side of photo), with lava moving from a source near the base of the cone toward the lava lake. Photo taken at 12:55 p.m. HST from the western rim of the crater. USGS photo by J.M. Chang. 2. Screenshot of USGS-HVO's F1 thermal webcam on November 14, 2021 at 4:14am HST, showing the two new outlets as bright yellow and orange flows near the bottom of the image on either side of the darker purple cone with the bright center. 3. A telephoto view of the flow on the south side of the west vent cone within Halema‘uma‘u crater, at the summit of Kīlauea. The direction of flow is from the west (bottom) to the east (top). Entrained pieces of solidified crust (black) can be seen in the flow and can be used to determine the direction of flow. Photo taken from the western rim on November 15, 2021, at 12:52 p.m. HST. USGS photo by J.M. Chang.


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