Undersea pictures of lava from Kama’ ehu volcano, contrasting fresh-looking young lavas (top) versus older sediment-covered lavas (bottom). Credit: The 2 images on the bottom are thanks to JAMSTEC.
The submarine Hawaiian volcano Kama ʻehuakanaloa, previously called Lōʻihi Seamount, located approximately 20 miles from the southern coast of Hawai’ i’s Big Island, has actually experienced a minimum of 5 eruptions in the previous century and a half, according to current research study carried out by Earth researchers at the University of Hawai’ i at Mānoa.
Scientists have, for the very first time, estimated the ages of Kama ʻehu’s most current eruptions, in addition to the ages of 8 more ancient eruptions from this volcano, tracing back almost 2,000 years. Their findings were released just recently in the journal Geology
Hawaiian volcanoes are believed to shift through a series of development phases. Kama ʻehu is presently in the earliest submarine “pre-shield” phase of development, whereas the active surrounding volcano Kīlauea remains in its primary shield-building phase.
“Kamaʻehu is the only active and exposed example of a pre-shield Hawaiian volcano,” stated Aaron Pietruszka, lead author of the research study and associate teacher in the Department of Earth Sciences at the UH Mānoa School of Ocean and Earth Science and Technology (SOEST). “On the other Hawaiian volcanoes, this early part of the volcanic history is covered by the great outpouring of lava that occurs during the shield stage. Thus, there is great interest in learning about the growth and evolution of Kama‘ehu.”
Kama’ ehu’s history exposed with chemistry and undersea videos
Previously, the just recognized and validated eruption of Kama ʻehu was the one that took place in 1996, an occasion that was just found since it accompanied a big swarm of earthquakes that were discovered from another location by seismometers on the Big Island.
“Seismometers can only be used to detect the ongoing active eruptions of submarine volcanoes because earthquakes are transient,” statedPietruszka “In order to determine the ages of older eruptions at Kamaʻehu, we took a different approach. We used a mass spectrometer to measure tiny amounts of the isotope radium-226 in pieces of quenched glassy lava that were sampled from the seafloor outcrops of Kamaʻehu using a submersible.”
Magma naturally includes radium-226, which radioactively decomposes at a foreseeable rate. So, Pietruzska and co-authors utilized the quantity of radium-226 in each sample to presume the approximate time expired because the lava emerged on the seafloor, that is, the eruption age of the sample.
Pietruszka began this examination several years earlier as a postdoctoral scientist at the < period class ="glossaryLink" aria-describedby ="tt" data-cmtooltip ="<div class=glossaryItemTitle>Carnegie Institution for Science</div><div class=glossaryItemBody>The Carnegie Institution for Science is a private, nonprofit organization based in Washington, D.C. that conducts scientific research and education. It was founded in 1902 by Andrew Carnegie and is one of the oldest independent research institutions in the United States. The Carnegie Institution for Science includes six research departments: Embryology, Observatories, Plant Biology, Global Ecology, Terrestrial Magnetism, and DTM (Department of Terrestrial Magnetism). It also has a number of affiliated programs and initiatives, including the Carnegie Academy for Science Education and the Carnegie Institution for Science's Department of Global Ecology.</div>" data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]" >CarnegieInstitution forScience, simply after completing his postgraduate degree in Earth science from SOEST.Once he went back to UH Mānoa in2019, he got access to submersible dive videos and images aroundKama’ ehu and had the info he required to complete linking the dots.
“The submersible dive images and videos provided independent confirmation of our estimates of eruption ages,” statedPietruszka“The lavas with the freshest appearance also had the most radium-226, and vice versa for the lavas with the ‘older’ appearance, that is, fractured and broken, and/or covered with marine sediment. I was surprised to discover that Kama’ehu had erupted five times within the last ~150 years, which implies a frequency of ~30 years between eruptions at this volcano. This is much slower than at Kīlauea, which erupts almost continuously (with infrequent pauses of only a few years).”
Chemical modifications in lava with time
The chemistry of the lava emerged fromHawaiian volcanoes modifications with time.The brand-new eruption ages for the lavas from(************************************************************************************************************************************************** )’ ehu, paired with measurements of lava chemistry, expose that the timescale of variation in lava chemistry at this pre-shield volcano has to do with 1200 years. In contrast, Kīlauea lava chemistry modifications over a timescale of just a few years to years, with a total cycle over about 200 years.
“We think that the origin of this difference is related to the position of the two volcanoes over the Hawaiian hotspot,” statedPietruszka “This is an area of Earth’s mantle that is rising toward the surface—a “mantle plume” that eventually melts to form the lava that provides Hawaiian volcanoes. Models and other isotope information from thorium-230 recommend that the center of a mantle plume need to increase faster than its margin. Our results– particularly, the element of 6 longer timescales of variation in lava chemistry at Kama’ ehu– offer independent verification of this concept.”
The research study group wishes to much better comprehend how Hawaiian volcanoes work from their earliest development phases to their complete, and often active, maturity to assist them comprehend the deep controls on volcanic eruptions that start within the strange, upwelling mantle plume under the Hawaiian hotspot.
Reference: “Slow changes in lava chemistry at Kama‘ehuakanaloa linked to sluggish mantle upwelling on the margin of the Hawaiian plume” by Aaron J. Pietruszka, Michael O. Garcia, Richard W. Carlson and Erik H. Hauri, 26 May 2023, Geology
DOI: 10.1130/ G513501
The research study was moneyed by the Carnegie Institution for Science and National Science Foundation.
