Kīlauea Eruption Update, Day 135: May 4, 2021

Kīlauea’s lava lake has crusted over nearly half of its active lava surface in the past two weeks while gas emissions remain low, yet the volcano continues to erupt at a low level. Based on USGS imagery and map area calculations, our updated estimates suggest close to a 50% reduction in the open lava lake surface over the past two weeks. Gas emissions over the past week ranged from 250-475 tonnes/day, similar to the previous week and less than half of the prior "rates that averaged over 800 t/day from mid-February to mid-April" according to USGS-HVO. Deflation-inflation cycles continue frequently (2 in the past week, and 7 in the past month), and as a result the lava level within the lake has only varied slightly from its average level of 745 ft (227 m), but in the past three days has twice crested close to 748 ft (228 m) in concert with inflationary phases. No new ooze-up flows have been observed along the lake’s perimeter, next to the crater walls, during the past 3 weeks now. An added note on the possibility of a pause in the eruption is included in recent USGS-HVO daily updates: "Recent SO2 emission rate measurements suggest that the effusion (eruption) rate has decreased significantly since mid-April. Other decreases in emissions during this eruption have occurred while summit tilt was decreasing, whereas the recent lows in emissions are independent of summit tilt. Drops in SO2 emissions are commonly related to decreases in lava supply, but other possibilities also exist. It is common for eruptions to wax and wane or pause completely. It is unclear if the current decrease in activity will continue and conditions around Halema‘uma‘u crater remain hazardous. HVO continues to monitor Kīlauea volcano closely for additional signs of changes in activity." Latest on Kīlauea, Eruption Day 135, Week 19: -Active lake surface further reduced by crusting, with the 2-week total in the range of 45-50% by our unofficial estimates. -GPS shows continued caldera spreading, with extension rate reverting back to recent average as a possible result of DI cycles. Seismic activity also has kept within background levels, focused mainly around the summit this past week. -- We review the details of the ongoing changes to the open lake surface using original time-lapse productions, live monitoring data and published photos and reports available courtesy of the USGS Hawaiian Volcano Observatory. As usual, we discuss live viewer questions! https://youtu.be/fUYZrigfDuo