According to a news release shared by the USGS on their social media channels, an eruption has commenced within Kaluapele— the summit caldera of Kīlauea volcano. The USGS Hawaiian Volcano Observatory is elevating Kīlauea’s volcano alert level from ADVISORY to WARNING and its aviation color code from YELLOW to RED as this eruption and associated hazards are evaluated.
Webcam images show a line of fissures erupting lava fountains feeding a flow within the summit caldera.
The eruption is occurring within a closed area of Hawai’i Volcanoes National Park. High levels of volcanic gases like water vapor, carbon-dioxide, and sulfur-dioxide, are the primary concern, as they can have far-reaching effects downwind of Kīlauea. Sulfur-dioxide can react with water vapor creating a volcanic haze also known as volcanic smog or vog. Vog can have negative health impacts, damage crops and create acid rain. A red warning includes the danger of plumes of volcanic ash in the higher layers of the atmosphere, possibly interfering with flight paths.
Kīlauea is one of the best monitored active volcanoes in the world. The mountain is covered with scientific instruments, from ground sensors that measure the shaking of the mountain to tools that analyze the gases released from the volcanic vents.
Kīlauea’s eruption style is generally dominated by a “harmless” effusive activity of lava pouring out from fissures, but the volcano can have phases of impressive explosive eruptions. In May 1924, about 60 explosions occurred sending fragments ranging from volcanic ash to large blocks the size of cars into the sky and falling back around the summit caldera.
In the last 35 years Kīlauea volcano erupted in two places: at the summit caldera and at the Pu‘u‘ō‘ō crater on the eastern rift zone. In May 2018, a large lava flow destroyed more than 700 residences on its path to the sea.
This change between effusive and explosive activity of Kīlauea is quite unique. In most volcanoes, explosive eruptions are either primarily driven by rising magma pressure, steam/vaporized groundwater, or some combination of the two. But at Kīlauea, the explosive eruptions are driven by a “stomp-rocket mechanism.”
During an effusive eruption characterized by lava fountains and flows, the magma reservoir is gradually emptied. The rocky roof above it—the ground within the caldera at the volcano’s summit—now lacking supports suddenly collapses, quickly increasing the pressure in the reservoir and squeezing gas and bits of rubble through the vents in Kīlauea’s crater.
A study published just a few months ago compared this mechanism to a stomp-rocket toy, where stepping on an air bag connected to a hose launches a projectile into the air.
The USGS will continue to closely monitor Kīlauea and adjust the alert level/aviation color code accordingly. Should volcanic activity change significantly, a new Volcanic Activity Notice will be issued.
