Kilauea’s summit is quiet again, but the pause is already on a clock. Episode 46 of the volcano’s ongoing fountaining eruption ran for roughly nine hours on May 5, 2026, pouring an estimated 6 million cubic yards of lava across about 60% of the Halema’uma’u crater floor, according to the U.S. Geological Survey’s Hawaiian Volcano Observatory. Now, based on the same summit tiltmeter pattern that has preceded every burst since the eruption cycle began on December 23, 2024, HVO has placed a preliminary forecast window for episode 47 between May 12 and May 17.
For the thousands of visitors who pass through Hawaiʻi Volcanoes National Park each week, for pilots routing flights over the Big Island, and for Kaʻū and Kona residents who track vog forecasts the way mainlanders check pollen counts, the countdown is already underway.
What episode 46 looked like
Fountaining began at 8:17 a.m. HST and continued until 5:22 p.m., giving HVO field crews an unusually long observation window. Lava fountains reached 500 feet (150 meters), and approximately 45 precursory overflows spread across the caldera floor before the main phase took hold, per HVO’s contemporaneous status report. The eruption plume climbed high enough to be visible from the Mauna Loa summit caldera, miles to the northwest.
Tephra fell at the Uēkahuna overlook and near a Highway 11 mile marker during the event, according to the same HVO report. The Washington Volcanic Ash Advisory Center, operated by NOAA, issued aviation advisories tracking the ash cloud in near real time, and HVO incorporated those plume-height measurements into its own updates. For airline dispatchers, the advisories flagged a localized but real hazard; for scientists, they provided an independent check on the eruption’s atmospheric reach.
The single-episode output of roughly 4.6 million cubic meters is a significant pour in a sequence that has been steadily rebuilding the crater’s lava lake over 46 bursts spanning more than 17 months. That volume estimate is preliminary, drawn from HVO’s initial field mapping and aerial imagery rather than a finalized post-event analysis, and it could be revised as better data arrive.
How episode 46 compares to the eruption cycle’s largest bursts
Readers tracking this eruption will naturally ask whether the episodes are getting bigger. The available HVO record shows that past bursts have varied widely in duration, fountain height, and lava volume, and the pattern has not followed a simple upward or downward trend across the 46 episodes logged since December 2024. Some earlier episodes delivered intense but brief fountaining, while episode 46’s roughly nine-hour run and 60% crater-floor coverage rank it among the longer and more voluminous events in the sequence. However, HVO has not published a formal ranking of episodes by output, and the volume figures for many earlier bursts remain preliminary estimates subject to revision. Without a finalized, side-by-side comparison from the observatory, any definitive claim that the eruption is escalating would outrun the data. What the record does show is that the cycle has sustained itself for more than 17 months without a clear trend toward exhaustion, and that individual episodes can still surprise in scale.
Why HVO expects episode 47 between May 12 and May 17
The forecast rests on a pattern that has held, with some variation, across every episode in this eruption cycle. After each fountaining burst drains magma from the shallow summit reservoir, the crater floor deflates. Then, as fresh magma rises from depth, summit tiltmeters record a steady inflation trend. When tilt reaches a threshold consistent with prior episodes, fountaining resumes.
HVO’s latest volcano update shows that familiar inflation is already underway, placing the preliminary window at May 12 to May 17. The word “preliminary” matters: if the inflation rate speeds up, stalls, or reverses, the window will shift. Volcanic systems can also break from established rhythms without warning, particularly when subsurface plumbing pathways evolve or magma supply fluctuates. Forty-six successful pattern matches do not guarantee a forty-seventh.
What the data does not yet show
Several questions remain open heading into the next episode. HVO has not published specific tilt values or seismic counts for the current pause, so outside analysts cannot independently verify the timing estimate. The observatory also has not released detailed elevation surveys of the current lava lake surface, which means any claim about how close the lake is to overtopping the crater rim would be speculation, not reporting.
Operational impacts from episode 46 are also incompletely documented. The National Park Service published closure notices and shelter-in-place guidance during episode 43 weeks earlier, and similar hazards were plausible during episode 46 given the tephra reports at Uēkahuna and Highway 11. But no episode-46-specific closure summary has appeared in the public record as of mid-May 2026. Wind direction, eruption intensity, and duration all influence whether tephra triggers road restrictions or visitor evacuations, and those variables change from one episode to the next.
Even the character of episode 47 is an open question. Past bursts have varied widely: some delivered intense but brief fountaining, while others, like episode 46, sustained activity for hours. HVO has not offered a specific forecast for fountain height, lava spread, or tephra reach for the next event.
What to watch as the forecast window opens
The most reliable real-time picture will come from three official channels. HVO’s volcano updates page carries status changes, tilt readings, and eruption notices as they are issued. The Washington VAAC’s advisories, archived and updated continuously, provide the aviation-grade plume tracking that airlines and pilots depend on. And the National Park Service posts trail and road closures, air-quality warnings, and visitor guidance tied to each episode’s specific conditions.
For Big Island residents, sulfur dioxide emissions remain a practical concern during active episodes. Elevated SO₂ from the summit vent feeds the vog that settles over leeward communities, and HVO routinely reports emission rates as part of its eruption monitoring. Checking those updates alongside state health advisories is the most direct way to gauge air-quality risk before and during the next burst.
Kilauea’s eruption cycle has now sustained itself for more than 17 months and 46 episodes with no sign of winding down. Each pause has ended the same way: with tilt climbing, pressure building, and lava returning to the crater floor. The data say the next round is days away. The open question is not whether episode 47 will happen, but exactly when, and how much of the remaining crater floor it will cover.
More from Morning Overview
*This article was researched with the help of AI, with human editors creating the final content.
