Scientists at the University of Hawaiʻi at Mānoa have successfully estimated the ages of several eruptions of the underwater Hawaiian volcano Kamaʻehuakanaloa. This marks the first time that the ages of these eruptions have been determined. The study, led by UH Earth scientists, analyzed the volcanic activity of Kamaʻehuakanaloa and identified its eruptions over the past 2,000 years, including the most recent ones.
Previously known as the Lōʻihi Seamount, Kamaʻehuakanaloa has erupted at least five times in the last 150 years. The research, recently published in Geology, sheds light on the growth and evolution of this unique volcano. While other Hawaiian volcanoes have their early volcanic history hidden by subsequent lava flows during the shield stage, Kamaʻehuakanaloa remains exposed, making it a valuable subject of study.
The discovery of previous eruptions at Kamaʻehuakanaloa was made possible by using a mass spectrometer to measure the isotope radium-226 in samples of lava collected from the seafloor. The decay of radium-226 provided scientists with a method to estimate the time elapsed since the eruption occurred.
The study also revealed that the chemistry of the lava erupted by Kamaʻehuakanaloa changes over a timescale of approximately 1,200 years. In contrast, the nearby active volcano Kīlauea experiences changes in lava chemistry over much shorter periods of only a few years to decades.
The differences in lava chemistry between the two volcanoes are believed to be linked to their positions over the Hawaiian hot spot, an area in Earth’s mantle that rises to the surface to form the magma feeding Hawaiian volcanoes. The research findings support the idea that the center of a mantle plume rises faster than its margins, as suggested by models and other isotope data.
Aaron Pietruszka, lead author of the study, conducted the research during his time as a postdoctoral researcher at the Carnegie Institution for Science. He gained access to submersible dive videos and photos of Kamaʻehuakanaloa, which were crucial in completing the study. Pietruszka was surprised to discover that Kamaʻehuakanaloa had erupted five times in the last 150 years, with an average frequency of 30 years between eruptions. This is significantly slower than the almost continuous eruptions of Kīlauea, which only experiences occasional brief pauses.
The research team’s ultimate goal is to gain a better understanding of how Hawaiian volcanoes operate, from their earliest stages of growth to their full maturity. This knowledge will help unravel the deep controls on volcanic eruptions originating from the mantle plume beneath the Hawaiian hot spot.