A current research carried out by Earth scientists on the College of Hawai’i at Mānoa reveals that Kamaʻehuakanaloa (previously Lōʻihi Seamount), a submarine Hawaiian volcano located roughly 20 miles off the coast of the Massive Island of Hawai’i, has skilled at the least 5 eruptions throughout the previous 150 years. The researchers efficiently estimated the ages of those eruptions, in addition to eight older eruptions relationship again round 2,000 years. The findings, which offer useful insights into the expansion and evolution of Kamaʻehu, have been revealed within the journal Geology.

Hawaiian volcanoes endure numerous progress levels, and Kamaʻehu is at present in its early submarine “pre-shield” stage, whereas the neighboring volcano Kīlauea is in the primary shield-building stage.

Aaron Pietruszka, lead creator of the research and affiliate professor within the Division of Earth Sciences at UH Mānoa College of Ocean and Earth Science and Expertise (SOEST), explains, “Kamaʻehu is the one lively and uncovered instance of a pre-shield Hawaiian volcano. On different Hawaiian volcanoes, this early stage is obscured by intensive lava flows that happen throughout the protect stage. Subsequently, there’s immense curiosity in understanding the expansion and evolution of Kama’ehu.”

Uncovering the Historical past of Kama’ehu By way of Chemistry and Underwater Movies

Previous to this analysis, the one confirmed eruption of Kamaʻehu was in 1996, which was found as a result of a coinciding swarm of earthquakes detected by seismometers on the Massive Island.

Pietruszka explains, “Seismometers can solely detect ongoing lively eruptions of submarine volcanoes as earthquakes are transient. To find out the ages of older eruptions at Kamaʻehu, we used a unique strategy. We measured tiny quantities of the radium-226 isotope in quenched glassy lava samples collected from the seafloor outcrops of Kamaʻehu utilizing a submersible.”

Magma naturally comprises radium-226, which decays radioactively at a predictable price. By analyzing the quantity of radium-226 in every lava pattern, the researchers have been capable of estimate the approximate eruption age.

This investigation began a number of years in the past when Pietruszka was a postdoctoral researcher on the Carnegie Establishment for Science. After buying entry to submersible dive movies and pictures round Kama’ehu upon his return to UH Mānoa in 2019, Pietruszka was capable of affirm the eruption ages utilizing the unbiased proof supplied by these visuals.

Pietruszka remarks, “The submersible dive photographs and movies supplied unbiased affirmation of our eruption age estimates. The lavas with a recent look had increased radium-226 ranges, whereas the lavas with an ‘older’ look, characterised by fractures, breakages, and sediment protection, had decrease ranges. I used to be stunned to find that Kama’ehu had erupted 5 instances throughout the final 150 years, indicating an eruption frequency of roughly 30 years, considerably slower than Kīlauea, which experiences virtually steady eruptions.”

Chemical Modifications Over Time in Lava

The lava chemistry of Hawaiian volcanoes undergoes modifications over time. By combining the newly estimated eruption ages of Kama’ehu lavas with lava chemistry measurements, the researchers discovered that the timescale of variation in lava chemistry at this pre-shield volcano is roughly 1,200 years. In distinction, Kīlauea experiences lava chemistry modifications over a timescale of just some years to a long time, finishing a full cycle in about 200 years.

Pietruszka explains, “We imagine that this distinction is linked to the place of the 2 volcanoes over the Hawaiian hotspot, which is an space of Earth’s mantle rising in the direction of the floor—a mantle plume that ultimately melts to type magma feeding Hawaiian volcanoes. Fashions and isotope information from thorium-230 assist the concept the middle of a mantle plume rises quicker than its margins. Our outcomes, significantly the sixfold longer timescale of lava chemistry variation at Kama’ehu, independently affirm this idea.”

The analysis staff goals to additional improve their understanding of the complete lifecycle of Hawaiian volcanoes, from their early progress levels to their mature and often lively phases. This information will assist unravel the deep-seated components influencing volcanic eruptions originating from the enigmatic, upwelling mantle plume beneath the Hawaiian hotspot.