Researchers from the University of Hawai’i at Mānoa have recently discovered that the Hawaiian undersea volcano, Kamaʻehu, also known as Kamaʻehuakanaloa or Lōʻihi Seamount, has erupted at least five times over the last 150 years. This information was gathered from undersea lava images that showcased both young fresh lavas and older sediment-covered ones.
This significant discovery was part of an investigation that also revealed the ages of eight additional, more ancient eruptions from the same volcano, dating back nearly 2,000 years. The study’s findings were published in the journal Geology.
Kamaʻehu is currently in its earliest “pre-shield” growth stage, while nearby Kīlauea is in its main shield-building phase. Kamaʻehu is unique as the only exposed active pre-shield Hawaiian volcano, thus offering a valuable opportunity to understand the early part of volcanic history in the region.
The history of Kama‘ehu’s eruptions was unveiled through chemical analysis and underwater videos. Before this research, the only known eruption of Kamaʻehu was in 1996, identified by coinciding with a major series of earthquakes. To determine the ages of older eruptions, the scientists used a mass spectrometer to measure radium-226 in the sampled lava. The amount of radium-226 helped them estimate the time since each eruption.
The submersible dive footage and photos provided validation for the eruption age estimates. Kama’ehu’s five eruptions over the last ~150 years suggest a frequency of around 30 years between eruptions, significantly slower than Kīlauea, which erupts almost continuously.
Further findings include the observation that the chemistry of the lava from Hawaiian volcanoes changes over time. Kama‘ehu’s lava chemistry varies on a 1200-year scale, while Kīlauea’s changes over a few years to decades. The origin of this difference is believed to be connected to the position of the two volcanoes over the Hawaiian hotspot.
The study, which was funded by the Carnegie Institution for Science and the National Science Foundation, contributes to a broader understanding of the Hawaiian volcanoes’ growth and maturity stages. It offers insights into volcanic eruptions related to the mysterious upwelling mantle plume under the Hawaiian hotspot.
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Frequently Asked Questions (FAQs) about Kamaʻehu
What volcano was the focus of the recent research by the University of Hawai’i at Mānoa?
The Hawaiian undersea volcano Kamaʻehu, also known as Kamaʻehuakanaloa or Lōʻihi Seamount, was the focus of the research.
How many times has Kamaʻehu erupted in the last 150 years?
Kamaʻehu has erupted at least five times in the past 150 years.
What method did the scientists use to determine the ages of older eruptions at Kamaʻehu?
The scientists used a mass spectrometer to measure tiny amounts of the isotope radium-226 in pieces of quenched glassy lava sampled from the seafloor outcrops of Kamaʻehu. This allowed them to infer the approximate time elapsed since the lava erupted on the seafloor.
What makes Kamaʻehu unique among Hawaiian volcanoes?
Kamaʻehu is unique as it’s the only active and exposed example of a pre-shield Hawaiian volcano. This provides a special opportunity to learn about the early part of volcanic history in the region.
How do the eruption frequencies of Kama’ehu and Kīlauea differ?
Kama’ehu has a much slower eruption frequency of around 30 years between eruptions, while the neighboring volcano Kīlauea erupts almost continuously, with only infrequent pauses of a few years.
What are the scientists hoping to understand through this research?
The research team aims to gain a deeper understanding of how Hawaiian volcanoes grow and mature, from their earliest stages to their full, frequently active maturity. This will help them comprehend the deep controls on volcanic eruptions initiated within the mysterious upwelling mantle plume under the Hawaiian hotspot.
More about Kamaʻehu
- University of Hawai‘i at Mānoa School of Ocean and Earth Science and Technology (SOEST)
- Geology Journal
- Carnegie Institution for Science
- National Science Foundation
