USGS has issued a VOLCANO WATCH, forecasting that an eruption will come soon to the Kilauea Volcano on the Big Island of Hawaii sometime between December 20 and December 30. Volcanologists say they will fine-tune their forecast further and narrow the window of likely eruption as they process more data. In addition to the watch, a color code alert of ORANGE has been issued.
The USGS Hawaiian Volcano Observatory (HVO) is responsible for issuing Aviation Codes and Volcanic Activity Alert Levels. Aviation Codes are green, yellow, orange, or red. When ground-based instrumentation is insufficient to establish that a volcano is at a typical background level of activity, it is simply “unassigned.” While green means typical activity associated with a non-eruptive state, yellow means a volcano is exhibiting signs of elevated unrest above known background levels. When a volcano exhibits heightened or escalating unrest with the increased potential of eruption, it jumps to orange. Finally, when an eruption is imminent with significant emission of volcanic ash expected in the atmosphere or an eruption is underway with significant emission of volcanic ash into the atmosphere, the code becomes red. Volcanic Activity Alert levels are normal, advisory, watch, or warning. As with aviation codes, if data is insufficient, it is simply labeled as “unassigned.” When the volcano is at typical background activity in a non-eruptive state, it is considered normal. If the volcano exhibits signs of elevated unrest above background level, an advisory is issued. If a volcano exhibits heightened or escalating unrest, a watch is issued while a warning is issued when a hazardous eruption is imminent.
Kīlauea has been erupting episodically since December 23, 2024, primarily from two vents (north and south) in Halema‘uma‘u inside the summit caldera. Eruptive episodes, which can last up to 12 hours, are separated by pauses that can be as long as two weeks.
The last episode occurred earlier this week, with a stunning display of lava shooting from multiple vents, ejecting lava and volcanic debris high into the sky. The December 6 eruption saw 12.1 hours of sustained lava fountaining. The south vent fountain began at 8:49 am local time and within 10-20 minutes all three fountains were about 500 feet high creating a rare triple fountain. By 9:40 am, the south vent fountain grew to about twice as high as the north vent fountains. According to USGS, the highest peak or instantaneous effusion rate of 1,300 cubic yards per second occurred just before 10 am when the south vent exploded. The enlarged south vent produced an inclined fountain over 1,000 feet tall that sprayed the south wall of Halemaʻumaʻu crater.
Hot pumice and molten spatter from this fountain destroyed the HVO “V3” streaming camera site.
Today, USGS said, “The rapid rebound of inflationary tilt, continued tremor, and moderate glow from both vents overnight all indicate another fountaining episode is likely. Based on preliminary models, the onset of another fountain episode is likely to occur between December 20 and 30. The forecast interval should become tighter as more data becomes available.”
This episodic eruption is occurring within a closed area of Hawai’i Volcanoes National Park. High levels of volcanic gas—primarily water vapor (H2O), carbon dioxide (CO2), and sulfur dioxide (SO2)—are one major hazard of concern, as this hazard can have far-reaching effects downwind. As SO2 is continuously released from the summit during an eruption, it will react in the atmosphere to create the visible haze known as vog (volcanic smog) downwind of Kīlauea. SO2 and vog may cause respiratory and other problems at high concentrations.
Another major hazard is fallout of Pele’s hair and other volcanic fragments from lava fountains. Pele’s hair is strands of volcanic glass often produced by lava fountaining activity that can be carried well over 10 miles (15 kilometers) from the vent. Other hot glassy volcanic fragments (tephra) including volcanic ash, pumice, scoria, and reticulite can fall on the ground within 1–3 miles (1–5 kilometers) of the eruptive vent(s), with the highest concentrations immediately downwind of the vent(s). Various volcanic fragments have fallen on Highway 11 west of Hawai’i Volcanoes National Park at times, depending on wind and eruption conditions. Strong winds may waft light particles, including Pele’s hair, to greater distances downwind. Once on the ground, Pele’s hair can sometimes cluster and tangle together, giving it the appearance of a tumbleweed. The extent of Pele’s hair deposition is dependent on lava fountaining activity and wind conditions. Residents and visitors should minimize exposure to Pele’s hair and other glassy volcanic fragments, which can cause skin and eye irritation and can also contaminate catchment water supplies
