USGS Kilauea Update, January 11, 2021

Activity Summary: Lava activity is confined to Halemaʻumaʻu with lava erupting from vents on the northwest side of the crater. This morning (Jan. 10), the lava lake is about 196 m (643 ft) deep below the west vents while remaining stagnant over its eastern half. SO2 emission rates were still elevated. Summit Observations: The most recent sulfur dioxide emission rate measurements were 2,300 t/d on Sunday (Jan. 10) and 2,700 t/d on Thursday (Jan 7)-- with uncertainties of about 700 t/d, these values are on the low end of the range 3,000-6,500 t/d since Dec. 27 (the same range of emission rates from the pre-2018 lava lake). Summit tiltmeters recorded continuing inflationary tilt. Seismicity remained elevated but stable, with steady elevated tremor and a few minor earthquakes. East Rift Zone Observations: Geodetic monitors indicate that the upper portion of the East Rift Zone (between the summit and Puʻu ʻŌʻō) contracted while the summit deflated at the onset of this eruption. There is no seismic or deformation data to indicate that additional magma is currently moving into either of Kīlauea’s rift zones. SO2 and H2S emissions from Puʻu ʻŌʻō were below instrumental detection levels when measured on Jan. 7. Halemaʻumaʻu lava lake Observations: The west vents exhibited stronger flow starting yesterday afternoon with spattering and spatter-fed lava flows from the top of small cones plastered on the northwest wall of Halemaʻumaʻu crater. Lava also flowed from the west vents through a crusted channel into the lake. The lava lake was about 196 m (643 ft or 214 yds) deep below the west vents this morning (Jan. 11) while the stagnant eastern half of the lake was about 3-4 m (3-4 yds) shallower. Last night (Jan. 10) the eastern part of the lake appeared to have subsided below its perched rims. Overall, the dimension of the lake remained the same. The lake was still perched at least 1-2 m (1-2 yds) above its narrow edges even though the eastern half of the lake appeared stagnant this morning. All islands were stationary over the past day as if frozen in the eastern stagnant portions of the lava lake. The dimensions of the main island remained unchanged with its edges several meters (yards) above the lake surface. Friday afternoon, (Jan. 8), the west end of the island was measured as 9 m (10 yds) with the high point 23 m (25 yds) above the lake surface. Near-real time webcam views of the lava lake can be found here: https://volcanoes.usgs.gov/volcanoes/kilauea/multimedia_webcams.html. --- Images and captions from USGS. Image 1: Around sunset on Saturday (January 9, 2021), a break in the rain allowed HVO scientists to visit and monitor the ongoing eruption in Halema‘uma‘u. The west vent is still actively effusing lava, but outflow into the lava lake is increasingly sluggish, as evidenced by slow-moving crustal plates near the once-vigorous vent outlet. Also, much of the crust in the eastern half of the lake has stagnated completely, likely because the lake level has not changed significantly in the past three days. USGS photo by H. Dietterich. Image 2: The arrival of nightfall at Halema‘uma‘u on January 9, 2021, provided a clearer view of ongoing eruptive activity for USGS scientists monitoring the eruption this Saturday evening. This photo is focused on areas of active crustal motion in the western half of the lava lake; the eastern half (off to the right) is mostly stagnated and displays significantly less incandescence. The west vent, still actively effusing lava but at a diminishing rate, is visible to the upper left of the lake. USGS photo by H. Dietterich. Image 3: Graph showing the depth of the Halema‘uma‘u crater lava lake at Kīlauea Volcano's summit. HVO scientists measure the Kīlauea summit lava level using a small laser rangefinder mounted on a tripod. Measurements began one day after the start of the eruption on December 20, 2020 and are updated by geologists making observations from the field. HVO field crews use a laser range finder to measure the vertical distance between points of known elevation and the lava lake surface. Multiple measurements are taken and the average solution is plotted. Variations in plotted depth can occur due to alternating field crews, the uneven surface of the lava lake, or laser rangefinder returns on gas rather than the lake surface.