Hawaiian Volcano Update: Kīlauea Summit Eruption’s Episodes 19 & 20 - May 8, 2025

The 19th episode of Kīlauea’s ongoing summit eruption began its fountaining phase one week ago at 9:28 pm on Thursday, May 1, reaching peak heights of 330 feet or 100 meters over its nearly 8-hour duration. Episode 19 “produced just under 4 million cubic yards (3 million cubic meters) of lava and the flows covered about half of the Halemaʻumaʻu crater floor” according to the USGS-HVO. Dominant trade winds over the past week limited the impact of increased volcanic gas and tephra output during both episodes 19 and 20, although some residents farther downwind in Ocean View noted Pele’s hairs on parked vehicles. After a shorter than usual pause of 3 days, episode 20 began with intermittent lava overflows on Monday, May 5 at 10:48 am, and was followed by its sustained fountaining phase 31 hours later on Tuesday, May 6 at 5:28 pm. Episode 20’s highest fountains reached over 500 feet or 150 meters, feeding flows that once again covered about half of the crater floor with roughly 3 million cubic yards (2.5 million cubic meters) of new lava, over an also shorter than usual 4.5 hours. “The effusion rate during the first 30 minutes of sustained fountaining was on the order of 262 cubic yards (200 cubic meters) per second,” and averaged about 153 cubic yards (140 cubic meters) per second. The north vent produced most of the lava overflows and fountains in both episodes 19 and 20, with the south vent also weakly active. As with previous episodes, the volcano has resumed inflating due to new magma gathering beneath the summit, such that “data indicate that episode 21 is likely to start in the next 3-6 days. The window may be adjusted as more data become available.” Gas emissions and tephra fallout remain the primary hazards for people in nearby communities, although trade winds are forecast to continue for many days, likely limiting the impact similar to this past week. Sulfur dioxide emission rates of about 1,750 tonnes per day (t/d) were measured “on May 2 during the pause between episodes 19 and 20. SO2 emission rates of 4,000 to 6,000 t/d were measured during gas-pistoning events during episode 20 precursory low-level activity on May 5-6. SO2 emission rates during episode 20 sustained fountaining were likely up to 50,000 t/d based on measurements recorded during previous episodes.” Vog hazards and by now tephra fallout are not new to island residents, and the usual precautions and preparations apply, especially for those with respiratory sensitivities – more information at https://vog.ivhhn.org/. Maunaloa continues to inflate quietly its established post-2022 eruption pattern, with only small-magnitude earthquakes and minor adjustments evident on monitoring instruments. And yet the mountain continues to slowly rise, as shown by its summit GPS station gaining nearly 3 inches (7 centimeters) in height over the past year. As usual, we summarize the monitoring signals, imagery, and reports for both volcanoes available courtesy of the USGS Hawaiian Volcano Observatory, annotating the presentation on screen as we go, and discussing live viewer questions.