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Kīlauea Eruption Update, 4 Months In: April 14-20, 2021 (Week 17)

8:40 PM · Apr 20, 2021

As Kīlauea’s ongoing eruption reaches the four-month milestone, its output rate continues to gradually decline. Still, lava continues flowing into and filling a summit lava lake within Halemaʻumaʻu crater. According to the USGS Hawaiian Volcano Observatory, “the lava stream [into the lake] was covered in a thin, flexible crust and was moving at a very slow velocity.” Other than small changes in the lake entry, occasional small flows continue around the West Vent. Still no signs of any major change in the eruption apparent in monitoring signals, and the low-effusion phase continues. Latest on Kīlauea, Eruption Day 121, and statistics through 4 months: -West Vent entry points remain submerged, and their pathways crusted over, though occasional increases in flow lead to overflows from the cones -- this week towards the crater wall, last week into the lake -Lava lake crested at 745 ft / 227 m deep during the past week (USGS). The lake filled 663 ft / 202 m during the first month, 55 ft / 16 m in the second month, 14 ft / 5 m in the third month, and 9 ft / 3 m in the past month. -Small, triple Deflation-Inflation event ongoing; correspondingly, lake surface lowers slightly to 741 ft / 226 m deep, and no ooze-up flows along crater walls during past week. -GPS across summit caldera measuring continuing extension, but at a slower rate over the past month. Seismic activity below background, mostly focused below summit and South Flank. -SO2 last week measured at 950 tonnes/day (USGS), within average range of the past 2 months. Maximum reported emissions of 50,000 t/d during the first month, 2,200 t/d in the second month, 1,100 t/d in the third month, and 1,200 t/d during the past month. -Total eruption area 44 hectares / 109 acres, active lake area down to 3 hectares / 8 acres -Lake volume 39 Million cubic meters / 10 Billion gallons -Unofficial estimated output over the past month of ~20 ft3/s / ~0.5 m3/s. First month ~400 ft3/s / ~10 m3/s, second month ~80 ft3/s / ~2 m3/s, third month ~40 ft3/s / ~1 m3/s. (Peak ~3200 ft3/s / ~90 m3/s on the second day; average over the whole eruption ~140 ft3/s / ~4 m3/s from calculations based on preliminary USGS data reports.) Join our weekly live video review of Kīlauea’s eruption! Broadcast at 5pm HST Tuesdays and archived, along with short video updates, on this channel - including monitoring signals, photos & videos, time-lapses, geologic context and annotation, and discussion of live viewer questions. #Kilauea2021 Images: 1. A view of the lava lake from the east rim of Halema‘uma‘u Crater, at the summit of Kīlauea. The active portion of the lake is present at the far (western) end of the crater. USGS photo by M. Patrick on April 16, 2021. 2. A close-up view of the western fissure within Halema‘uma‘u at the summit of Kīlauea Volcano, Island of Hawai‘i. Lava continues to enter the lava lake from a wide inlet near the base of the western vent (fuming at center right). Crustal foundering is common on the active lava lake surface (center bottom), located on the western side of the crater. This photograph was taken on April 14, 2021, at 1:53 p.m. HST from the south rim of Halema‘uma‘u, an area within Hawai‘i Volcanoes National Park that remains closed to the public due to safety reasons. USGS photo by J.M. Chang. 3. A close up view of the inlet at the western margin of the lava lake in Halema‘uma‘u Crater, at the summit of Kīlauea. The lava stream was covered in a thin, flexible crust and was moving at a very slow velocity. USGS photo taken by M. Patrick on April 13, 2021. 4. A view of the south margin of the perched lava lake in Halema‘uma‘u Crater, at the summit of Kīlauea. This photo was taken from the east rim of the crater, and shows the steep levee containing the lake. USGS photo by M. Patrick. 5. This view from the south rim of Halema‘uma‘u shows the perched lava lake, supplied by lava from the western fissure (upper right portion of photo). The levee surrounding the active lava lake is up to about 5 m (16 ft) high. USGS photo by M. Patrick on April 13, 2021.

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