Just now, at 0415 hours local time, a significant explosion at the summit of Hawaii’s Kilauea volcano took place, creating a major plume of ash around 9,144 meters (roughly 30,000 feet) high.
Information is still coming in, but no-one appears to be in any immediate danger: Authorities have quickly explained that volcanological and National Park staffs have already been evacuated. The plume and ash fallout can be seen via the lone webcam in the area.
The latest advisory from the United States Geological Survey (USGS) explains that the explosion from the Overlook vent within Halema’uma’u crater created the sizeable ash column that drifted northeast. The column seems to have been short-lived.
“Continued emissions from the crater are reaching as high as 12,000 feet [about 3,670 meters],” it explains, adding that “at any time, activity may again become more explosive, increasing the intensity of ash production and producing ballistic projectiles near the vent.”
Sure, this may sound a little scary, but there’s no need to fret: This is all par for the course for this stage of Kilauea’s paroxysm; it's essentially what was expected to happen, and here’s why.
Yesterday, we explained what the new RED/WARNING alert status meant for Kilauea. In sum, it means that the explosivity at the summit crater, Halema’uma’u, could potentially get worse in the coming days.
Already, the period of increased ash emission was proving to be a danger to aviation and, perhaps, those on the ground downwind of it – but the scary-sounding red alert just meant things were going to get relatively more explosive, not Mount St. Helens-level explosive.
The uptick in the summit’s explosivity today, then, is almost certainly linked to the fact that the lava lake has drained dramatically recently. The magma in the conduit has fallen below the water table, which means that magma/lava-water interactions are taking place more frequently. This generates steam, and if the mixing rates are at an (as of yet undetermined) optimal level, it can create explosions.
At the same time, rocks are falling into the conduit from the already structurally unstable crater rim. This causes outbursts of ash, but larger rock falls that block the conduit can trigger a sudden increase in steam-based pressure, which has the potential to generate highly explosive depressurization events.
Similar water-driven explosions took place during the 1924 explosive eruption at Kilauea, and back then, boulder-sized volcaniclastic blocks were blasted out of the summit, which resulted in at least one fatality.
It’s thought that much the same is happening now. Wednesday’s update by the USGS' Hawaiian Volcano Observatory (HVO) provided the most recent detailed information about the ongoing events at Kilauea and the East Rift Zone. Peppered with plenty of noteworthy remarks, the one that got everyone’s attention is this:
“This morning dense ballistic blocks up to 60 cm (2 feet) across were found in the parking lot a few hundred yards from Halema’uma’u,” which means some significant explosive activity down there in the throat of the volcano is ejecting some microwave-sized ballistics skyward.
As the USGS noted in that same advisory, with regards to the fresh ballistics: “These reflect the most energetic explosions yet observed and could reflect the onset of steam-driven explosive activity,” adding that “further observations are necessary to assess this interpretation.”
The advisory adds that “additional such explosions are expected and could be more powerful,” and indeed that appears to be the case with the latest blast.
With this particular event, the ash fallout is likely to be the dominant threat here. Although only rarely deadly, it can cause problems to those with pre-existing respiratory ailments. Do your best to avoid it as it settles from the sky.
Details remain sparse, but don’t panic: This is, once again, a relative uptick in the explosivity at Kilauea. Don’t believe any nonsense about a Krakatoa-style explosion you may have seen elsewhere online. (A splendid rundown of the misinformation that’s gone around can be found here.)
Regardless of what happens next, the USGS, as ever, is just being cautious as they continually monitor the situation. You’ll be fine as long as you pay attention to what the HVO are saying and you don’t act recklessly.