Kīlauea Weekly Report, June 22, 2021

One month has passed since the last visible lava on Kīlauea, while subsurface magma movement continues. With no notable changes in this week’s USGS Hawaiian Volcano Observatory update, the only unusual monitoring signal over the past week is an apparent contraction across the summit caldera suggested by the GPS distance measurement. The magnitude of the summit-wide GPS signal is small and its significance is still unclear, as similar ranges of change during the eruption in January and February 2021 were concurrent with large Deflation-Inflation cycles (DI). Those ground-tilt cycles have persisted beyond the eruption, recently occurring at a rate of one large event per week, and have been considered a background process independent of other changes on the volcano. The baseline tilt over the past week is somewhat obscured by the DI, but appears to have at a minimum slowed its inflationary trend of the past month, if not ceased. The progression of the monitoring signals over the next few weeks will offer further clues to the adjustments within the volcano, as larger deflationary signals at its summit could signify a shifting balance of magma towards its upper east rift zone, which continues to refill, as stated for some time in USGS updates. Meanwhile, seismicity on Kīlauea continues similar to recent weeks, with slightly elevated activity near the volcano’s summit, upper east rift connector, upper east rift, and nearby south flank. Also reflected in the weekly USGS counts are the nearby deep Pāhala earthquakes, where a magnitude 4.5, on June 17th, was the largest event in the ongoing seismic swarm since August 2019, and was followed by about 40 aftershocks larger than magnitude 1.7 in the ensuing days. Gas emissions remain low within the new background range, with the most recent measurement registering 50 tonnes per day of SO2 on June 16th. No glow remains visible from the recent eruption, though small spots of remnant heat remain evident on the crusted lava lake surface and the West Vent. Taken altogether, are these signs of significant change, or of a new normal? Perhaps a little of both, as Kīlauea’s most recent surface activity was much shorter-lived than its previous, 35-year Puʻuʻōʻō eruption, and is the first to follow the 2018 summit collapse. The new normal may be more frequent changes near the surface driven by a long-term background trend of elevated magma supply at depth, with the 2020-2021 eruption as one of the first steps of that process. The volcano appears to already be slowly building pressure as we continue to await its next move. #Kilauea2021 Join our weekly live video review of Kīlauea and Maunaloa volcanoes, at 5pm Hawaiʻi time Thursdays as of June 2021! To support our productions please like, share and subscribe! Mahalo! Image 1: USGS-HVO map of Kīlauea showing earthquakes over the past week, colored by depth. Image 2: USGS-HVO graph of Kīlauea summit cross-caldera distance measured by GPS over the past year, showing a small change in the past week.