New Theory Explains Unusual Eruption Pattern of Kīlauea Volcano

Photo byPhoto by ruedi häberli on Unsplash

The 2018 volcanic eruption on Hawaiʻi's Kīlauea volcano, marked by 12 explosive outbursts, provides new insights into volcanic activity. These eruptions, which destroyed 700 homes and displaced over 2,000 people, showcased a unique and regular pattern that differed from typical volcanic behaviour, which usually lacks such regularity.

Traditional volcanic eruptions are usually driven by rising magma pressure or steaming groundwater. However, the 2018 Kīlauea eruptions did not align with these causes, as there were no significant changes in the volcano's temperature or chemistry before the events. This led scientists to consider a different trigger mechanism.

In 2019, volcanologists from the US Geological Survey proposed the "stomp rocket" mechanism to explain Kīlauea's eruptions. This theory suggests that the eruptions were caused by the collapse of the ground above a lava chamber, which compressed gases, rocks, and lava, forcing them to erupt violently, similar to how stepping on a stomp rocket forces the air out.

Recent research by a team from the University of Oregon, USGS, and Sichuan University supports this theory. They found that in 2018, magma flows drained from Kīlauea’s primary system and spread eastward, creating a 10-kilometer-long underground tunnel. Concurrently, a series of earthquakes shook the area. Models indicate that an earthquake-induced tunnel roof collapse could generate pressure sufficient to cause the observed high-altitude plumes.

The eruptions occurred during the initial phases of Kīlauea’s caldera collapse when enough magma had drained to cause the crust above the magma reservoir to drop. This collapse, characterized by a series of discrete earthquakes, decreased the reservoir's volume and increased pressure, leading to the eruptions.

The first nine eruptions in 2018 are remarkably consistent with the 'stomp' mechanism, suggesting it played a dominant role. While this is the first time such a mechanism has been considered, the collapse of a volcano’s crater has been observed in other eruptions, indicating it might be more common than previously thought.

Understanding these mechanisms is crucial for predicting and preparing for future volcanic eruptions. The 2018 Kīlauea eruption offers a valuable case study for advancing this knowledge.