Kīlauea Precursory Phase Extends to Record 6.8 Days Before Episode 55

Key points

• The current precursory phase has lasted 6.8 days, exceeding the previous record of 6.2 days before Episode 44.
• Spatter bursts at the north vent intensified overnight, reaching heights of 35-70 feet, but ceased by sunrise on Monday.
• Summit inflation has stalled since September 10, with the USGS noting that standard forecasting models are no longer reliable.
• The Volcano Alert Level remains at WATCH and the Aviation Color Code is ORANGE.
• Light trade winds are pushing the sulfur dioxide plume toward the southwest, potentially affecting Kaluapele if fountaining begins.

Background

The ongoing eruption at Kīlauea began in December 2024. Episode 54 concluded on August 25 after nine hours of fountaining. Since then, the volcano has entered a cycle of precursory activity, characterized by low-level lava overflows and intermittent tremor, as magma refills the shallow summit reservoir. Previous precursory periods have varied in length, ranging from a few hours to over two days, but the current 6.8-day duration is unprecedented for this eruption cycle.

How outlets are covering it

Big Island Video News and the USGS Hawaiian Volcano Observatory emphasize the unpredictability of the current phase, noting that inflation-based models are no longer valid. NatureWorldNews highlights the health risks associated with vog, particularly for residents with respiratory conditions, and notes that wind direction is pushing emissions toward the north rim. Big Island Now focuses on the forecast window, which has been extended due to the prolonged precursory activity. All sources agree that activity remains confined to the closed park area, with no evacuations ordered.

Why it matters

The extended precursory phase indicates a significant buildup of pressure in the shallow magma chamber, which could lead to a major fountaining episode. The uncertainty in forecasting models means that residents and visitors must remain vigilant for changes in air quality and park closures. The potential for vog and tephra to reach populated areas, such as Kaluapele, underscores the need for preparedness and adherence to official guidance.

What to watch

The USGS Hawaiian Volcano Observatory will continue to monitor summit inflation, tremor, and spatter activity. A separate aviation notice will be issued if Episode 55 fountaining begins. Residents and visitors should check air quality and park closure information before outdoor activities or travel to the summit.