Research conducted on the Kīlauea volcano in 2018 revealed a new type of volcanic eruption mechanism that involved a series of explosive eruptions driven by sudden pressure increases as the ground collapsed. These explosions were fueled by pressure increases that blasted plumes of rock fragments and hot gas into the air, similar to a stomp-rocket toy. Scientists from the University of Oregon, United States Geological Survey, and China’s Sichuan University published their findings in Nature Geoscience.
The explosions at Kīlauea were part of a sequence of events that included lava flows erupting from lower on the flank of the volcano, causing destruction to homes and displacement of residents on the Island of Hawai’i. By understanding past volcanic eruptions, researchers can make better forecasts about future eruptions and provide more accurate warnings to those in the eruption’s path. Explosive volcanic eruptions are typically driven by rising magma, vaporized groundwater, or a combination of the two, but the eruptions at Kīlauea did not fit into these conventional categories.
The team had access to a wealth of data due to the regularity and similarity of the explosive eruptions, allowing them to analyze the dynamics of the eruptions in more detail. Through atmospheric and subsurface modeling, the scientists pieced together a new story about what took place at Kīlauea during the series of events in 2018. Magma draining from an underground reservoir before each explosion caused the ground above it to collapse, increasing pressure in the reservoir and leading to the eruption of magmatic gas and rubble through a vent in the crater.
The researchers described the eruption dynamic as a stomp-rocket mechanism, comparing it to a toy where stepping on an air bag launches a projectile into the air. The caldera collapse, although common, revealed this specific mechanism for the first time, suggesting that it may have occurred in other volcanic events as well. The study also linked geophysical observations to the properties of the volcanic plume in the atmosphere, providing new ways to observe and assess volcanic eruptions.
While the series of smaller eruptions at Kīlauea made it easier to identify the stomp-rocket mechanism, the volcano itself is complex, with magma ascent pathways that are geometrically complex. Advanced scientific instruments on the volcano offer researchers a nuanced picture of volcanic plumbing systems, allowing a deeper understanding of volcanic processes and eruption dynamics. The study highlights the importance of ongoing research and observation of volcanic activities for hazard assessment and preparedness.