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.