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Kīlauea Eruption Update, Dec 30 - Cyclic Activity

2:27 AM · Dec 31, 2020

Written with Philip Ong: While for the most part the eruption remains stable, there have been some fluctuations in volcanic activity at the summit of Kīlauea today. Around 6:00am this morning the seismic tremor associated with the eruption at the summit increased, and remained elevated until roughly 10:00 am. It also appears there was a small deflationary signal recorded by summit tiltmeters that corresponds to the increased tremor and activity. The increase in activity was relatively small, and not clearly identifiable on the USGS thermal cam overlooking the lava lake. The depth of the lava lake is now at 596 feet, rising a few feet from yesterday’s measurement of 591 feet deep. The western eruptive vent has remained active since the December 26th vent transition, when the previously active northern vent was submerged beneath the surface of the lake, ceased erupting, and instead drained the lava lake back into the shallow summit system of the volcano. The rafted island of hardened lava seen at the surface of the lava lake continues to drift slowly around the lake. Measurements taken by USGS give the dimensions of the rafted island at 820 feet by 440 feet wide, and raised above the surface of the lava lake by 20 feet. The dimensions of the lava lake itself are now 2,520 feet by 1,605 feet, making the widest part of the lava lake almost exactly 7 football fields long when including both end-zones. The lava erupting at the active western vent has been flowing down the steep 130+ foot crusted-over lava channel into the surface of the lava lake, while the upper part of the fissure that vents gas has apparently cycled between weak lava fountains and periods of gas driven Strombolian activity. The term “Strombolian” comes from the kind of eruptions typified at the Italian volcano Stromboli, where eruptions with frequent, but discrete explosions eject lava into the air. The 2018 eruption also had some Strombolian activity early on at Fissure 17 and later at Fissure 22, which built a large symmetrical spatter cone over the course of July. East Rift Zone - There have been no changes at the summit to indicate magma is moving into the rift. According to USGS, magma stored in the upper East Rift Zone could have been moving from the rift back towards the summit in response to the ongoing eruption, the opposite pattern than that seen in 2018. Images and captions from USGS (captions in the order images appear) - Image 1: Overnight, HVO field crews observed sporadic Strombolian type activity from the Kilauea 2020 western vent (minor explosive bursts of lava). The area remains closed to the public for safety reasons & HVO field crews are equipped with a range of specialized safety gear and PPE - Image 2: lava lake has changed little in past few days. West vents spatter while erupting lava flows into Halemaʻumaʻu crater via crusted-over channels. Depth ~ 181 m (593 ft) Volume ~23 million cubic meters (30 million cubic yards or 5.2 billion gallons). - Image 3: HVO field crews observed activity within Halema‘uma‘u, at Kīlauea Volcano's summit, overnight from within a closed area of Hawai‘i Volcanoes National Park. The area remains closed to the public for safety reasons and HVO field crews are equipped with a range of specialized safety gear and personal protective equipment. In the early hours of December 30, the western vent in the wall of Halema‘uma‘u continued to erupt primarily effusively (flowing lava), but sporadic strombolian activity (minor explosions ejecting lava into the air) was also observed at the top of the west vent. USGS photo by H. Dietterich. - Image 4: Animated GIF of lava erupting from a fissure at Kīlauea Volcano at night time on December 27, 2020.

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