Kamaʻehuakanaloa (formerly Lōʻihi Seamount, which was renamed in July 2021 by the Â鶹´«Ã½ Board on Geographic Names), a submarine Hawaiian volcano located about 20 miles off the south coast of Â鶹´«Ã½ Island, has erupted at least five times in the last 150 years, according to new research led by Earth scientists at the University of Â鶹´«Ã½ at Mānoa. For the first time, scientists were able to estimate the ages of the most recent eruptions of Kamaʻehu, as well as the ages of eight older eruptions at this volcano going back about 2,000 years. The findings were published in .

Hawaiian volcanoes are thought to transition through a series of growth stages. Kamaʻehu is currently in the earliest submarine “pre-shield” stage of growth, whereas the active neighboring volcano Kīlauea is in its main shield-building stage.

“Kamaʻehu is the only active and exposed example of a pre-shield Hawaiian volcano,” said Aaron Pietruszka, lead author of the study and associate professor in the at UH ²Ñā²Ô´Ç²¹â€™s (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 Kamaʻehu.”

°­²¹³¾²¹ʻ±ð³ó³Ü’s eruption history

Previously, the only known and confirmed eruption of Kamaʻehu was one that occurred in 1996, an event that was only discovered because it coincided with a large swarm of earthquakes that were detected remotely by seismometers on Â鶹´«Ã½ Island.

“Seismometers can only be used to detect the ongoing active eruptions of submarine volcanoes because earthquakes are transient,” said Pietruszka. “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 contains radium-226, which radioactively decays at a predictable rate. Pietruzska and co-authors used the amount of radium-226 in each sample to infer the approximate time elapsed since the lava was erupted on the seafloor, that is, the eruption age of the sample.

Pietruszka started this investigation many years ago as a postdoctoral researcher at the Carnegie Institution for Science, after finishing his doctoral degree in Earth science from SOEST. Once he returned to UH Mānoa in 2019, he got access to submersible dive videos and photos around Kamaʻehu and had the information he needed to finish connecting the dots.

“The submersible dive images and videos provided independent confirmation of our estimates of eruption ages,” said Pietruszka. “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 Kamaʻehu 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 changes in lava

The chemistry of the lava erupted from Hawaiian volcanoes changes over time. The new eruption ages for the lavas from Kamaʻehu, coupled with measurements of lava chemistry, reveal that the timescale of variation in lava chemistry at this pre-shield volcano is about 1,200 years. In contrast, Kīlauea lava chemistry changes over a timescale of only a few years to decades, with a complete 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,” said Pietruszka. “This is an area of Earth’s mantle that is rising toward the surface—a ‘mantle plume’ that ultimately melts to form the magma that supplies Hawaiian volcanoes. Models and other isotope data from thorium-230 suggest that the center of a mantle plume should rise faster than its margin. Our results—specifically, the factor of six longer timescale of variation in lava chemistry at Kamaʻehu—provides independent confirmation of this idea.”

The research team hopes to better understand how Hawaiian volcanoes work from their earliest growth stages to their full, and frequently active, maturity to help them understand the deep controls on volcanic eruptions that initiate within the mysterious, upwelling mantle plume under the Hawaiian hotspot.

–By Marcie Grabowski

On June 3, for the first time since 2019, the hosted by the (CSAV) at the , welcomed a class of 12 participants from around the world.

The eight-week summer course is designed to assist volcanologists and technicians from developing nations in attaining self-sufficiency in monitoring volcanoes. The field training on Â鶹´«Ã½ Island and in Vancouver, Washington, emphasizes volcano monitoring methods, both data collection and interpretation, in use by the U.S. Geological Survey (USGS). The participants also learn proper use and maintenance of volcano monitoring instruments.

The program was initiated in 1991 as a collaborative effort among the UH Hilo , the (HIGP) at UH ²ÑÄå²Ô´Ç²¹, and the USGS . More than 30 individuals will be contributing to the course this year, with instruction provided by HIGP and UH ²ÑÄå²Ô´Ç²¹ faculty, and current and retired USGS staff from the Hawaiian Volcano Observatory, Cascades Volcano Observatory and Alaska Volcano Observatory.

“Hawaiian volcanoes are among the most active in the world, but unlike violently explosive volcanoes, they can be approached and studied without significant risk,” said Don Thomas, director of CSAV and faculty member at HIGP in the UH ²ÑÄå²Ô´Ç²¹ . “As a result, the course and Â鶹´«Ã½ Island provide the ideal environment for practicing volcano monitoring techniques.”

Monitoring, analyzing and interpreting data

The curriculum covers available monitoring technology, but emphasizes technology that is accessible to the volcano observatories in participants’ home countries. Attendees learn to properly install seismic stations, precision GPS stations and tiltmeters; and analyze and interpret data from those types of equipment. They also practice monitoring and interpreting the chemistry of volcanic gas emissions; mapping lava flows and explosive deposits, and interpreting those maps in the context of eruption magnitude and risk; and assessing satellite remote sensing and thermal imagery.

“We also provide training on crisis management during a volcanic crisis: how to interact with the media during a crisis, how to educate the general public about volcanic hazards, and how to respond during a volcanic crisis,” said Thomas. “With this focus on forecasting and rapid response, we really aim to bolster volcano observatories around the world in their efforts to save lives and property.”

Connecting colleagues around the world

Since 1991, 264 from 30 countries have participated in the training program. Most attendees have been funded through the USGS Volcano Disaster Assistance Program with funding from USAID. The vast majority of participants are volcanologists or technicians actively monitoring volcanoes in their home countries. A typical cohort consists of trainees from five or six different countries, providing a valuable opportunity for international practitioners focused on volcanic hazards to connect.

“As the cohort progresses through the training program, they become colleagues with similar interests, work objectives and common challenges in fulfilling their volcano monitoring roles,” said Thomas. “After they return home, they have a network of colleagues that they can call on for help in problem-solving and brainstorming and dealing with the inevitable challenges that they’ll face in dealing with their home volcanoes.”

—By Marcie Grabowski

Earth scientists from the University of Â鶹´«Ã½ at Mānoa were gifted a set of precious basalt samples collected by the U.S. Geological Survey (USGS) from the Kīlauea Iki lava lake between 1959 and 1988. Investigating these samples will provide new insights for understanding recent and future volcanic eruptions in Â鶹´«Ã½.

“This set of lava core samples is one-of-a-kind. This type of multiple decade-long sampling of a magma body will unlikely be ever done again in Â鶹´«Ã½ or elsewhere,” said Tom Shea, earth sciences assistant professor in the UH Mānoa (SOEST).

In 1959, a large eruption filled an existing crater at the summit of Kīlauea with a lava lake. Over the next three decades, USGS drilled into this area to collect cores of cooling lava, noting the date, location and temperature of the rocks.

“This set of lava cores represents a remarkable, 30-year-long magma cooling experiment that enables us to track chemical changes in olivine through time, to see if they behave like faithful ‘crystal clocks’,” said Shea.

From thin sections to lava cores

Previously, Shea and his team had analyzed thin slices of these samples, shared by USGS collaborator Rosalind Helz. Olivine, the light green mineral common in basalt, acts as a type of crystal clock. It records progressive smearing of the boundaries between different elemental compositions, a change that occurred over the decades of cooling of the lava lake. Volcanologists typically use the distribution of chemical elements, from core to rim, to infer time since the eruption.

Nabila Nizam, a doctoral candidate in the SOEST , works with Shea on crystal clocks as part of a National Science Foundation-funded CAREER project, investigating how distinct chemical zoning in olivine grains gets progressively smeared with time. In the course of her work on the thin sections, she and Shea discovered that the Hawaiian Volcanoes National Park wanted to find a new home for some Kīlauea Iki drill cores. USGS collaborator Frank Trusdell worked hard with them on a drill core rescue mission.

“We set out on several trips to the National Park to characterize what was there, and clean and select some subsamples,” said Nizam. “Every box we opened was like viewing another surprise! Eventually, we shipped two full drill core sets (16 core boxes for each set) by boat to Honolulu earlier this year.”

These boxes of drill cores will be housed at SOEST and will be a part of research projects and available for appreciation.

“It’s thrilling to host this treasure trove of samples,” added Shea. “They have beautiful olivine crystals that will provide unmatched constraints on the rate at which different elements move within a mineral with time.”

The cores will allow the researchers to ground the theoretical cooling model that Earth scientists have been working with. With these samples, they know the exact timing and the temperature the lava lake was when the samples were collected.

–By Marcie Grabowksi

The eruption of Maunaloa has created a fiery living laboratory and real world classroom for students, faculty and staff at the .

Steve Lundblad, a professor, took his introductory geology class on an excursion two days after the first fissure opened to safely view the flow from Saddle Road. They based their observations at Gilbert Kahele Park.

“We talked about Maunaloa and Maunakea, and the Maunakea cinder cones surrounded by newer Maunaloa lava flows,” Lundblad explained. He expressed, students were mostly busy looking at the eruption through binoculars.

The curriculum of Lundblad’s class is designed to prepare students for further studies in geology. They study the features and materials that make up Earth, with emphasis on structures, various erosional and depositional processes, and the role of plate tectonics.

Lava sample study

Staff from the U.S. Geological Survey’s (USGS-HVO) continue to collect and bring samples of fresh lava to the UH Hilo for analysis on the Energy Dispersive X-Ray Fluorescence spectrometer, commonly called the EDXRF machine, which analyzes groups of elements simultaneously.

“Our student worker Baylee McDade will help prepare the samples, grinding them into powder, for analysis on the EDXRF machine…after the rocks finish in the drying oven,” said Darcy Bevens, an educational specialist at the UH Hilo .

“The analysis will give HVO details about the composition of the rock,” Bevens added.

Lundblad and colleague Peter Mills, an professor, have operated the X-Ray Fluoresence Spectrometer for the past 20 years, working on archaeological materials.

In past years, they also have worked with geology lecturer Cheryl Gansecki on newly erupted samples from KÄ«lauea—and now this week, Maunaloa—to track changes in the eruption. They do this by taking samples from the active flows, which are run through the EDXRF machine and analyzed for changes from one sample to the next.

In-depth tracking

UH Hilo has been analyzing lava flow samples from KÄ«lauea since 2013 however the composition barely changed until May 2018. First there was magma that had been stored, older, colder, and then as the fissures progressed, the scientists started to see, younger, hotter, magma coming in. This type of lava is more fluid and can travel longer distances.

“We successfully tracked changes during the 2018 eruption from magma that was stored in the lower East Rift zone to new magma that traveled from the summit reservoir,” Lundblad said.

The chemical change detected by the UH Hilo team preceded the change in Kīlauea’s eruptive behavior by two to three days which gave officials advanced warning in their task of protecting the public.

Now the UH Hilo team is at work on the Maunaloa flows.

“Because Maunaloa is a new eruption, we are hoping to help the USGS-HVO folks track changes from the early phases of the eruption to later stages,” Lundblad said.

For more information go to .

Most people in Â鶹´«Ã½ are familiar with—olivine—a gorgeous light green mineral in basalt rock that makes Mahana Beach on Â鶹´«Ã½ Island one of the few “green sand” beaches in the world. Researchers are using olivine as a type of “crystal clock,” where its chemical make-up (in particular how its chemical elements are distributed from core to rim) can be analyzed and exploited to read time information. Leading the investigation is a assistant researcher, who received $554,181 from a National Science Foundation CAREER award over the next five years.

Thomas Shea plans to experimentally calibrate these crystal clocks in a lab and apply the findings to understand natural systems on Â鶹´«Ã½ Island.

“UH has for many decades been an essential component and leader in the study of active volcanoes,” said Shea, who works in the ’s . “I hope to continue this long tradition of conducting frontier volcanological research with many of my colleagues at UH and in collaboration with the Hawaiian Volcano Observatory, part of the United States Geological Survey. Â鶹´«Ã½ is such a special place on Earth geologically, and we consider the study of our dynamic environment and natural hazards an absolutely critical mission of UH.”

Getting students informed and interested in Earth science careers is of utmost importance for Â鶹´«Ã½ and one of the major endeavors of the five-year award. With respect to the research components, given the destructive outcome of the last large eruption at Kīlauea volcano in 2018, better understanding the timing of events that happen underneath the surface prior to these eruptions is also of key significance for Â鶹´«Ã½.

An exploratory aspect of the work planned for this award is to use a set of samples that were collected from a hot lava lake over nearly 30 years (1959-88). A large eruption filled an existing crater at the summit of Kīlauea in 1959 with a lava lake, and this lake formed a hard crust and took more than 40 years to fully solidify (62 years later, that lava is no longer molten but still hot deep underneath).

During those years, scientists drilled through the hard crust to sample lava at the different depths, and repeatedly over three decades.

“Today we have a remarkable time series of samples from the 1960-80s that are sort of like a 30-year-long magma cooling experiment where we can track chemical changes in the olivine and see if they behave like faithful ‘crystal clocks’ that we will be able to leverage for more recent and future eruptions,” said Shea.

This work is an example of UH ²Ñā²Ô´Ç²¹â€™s goal of (PDF), one of four goals identified in the (PDF), updated in December 2020.

Promoting Earth sciences to Â鶹´«Ã½ students

The educational component of the award proposes to use hands-on experimentation and active learning to get Â鶹´«Ã½ students (particularly at the pre-college level) excited about STEM and discover some of the fascinating facets of Earth sciences. This will involve both on-site activities and programs at UH and going to classrooms in high schools around Oʻahu and potentially Â鶹´«Ã½ Island.

“Part of our mission as scientists and teachers—and our responsibility to the state of Â鶹´«Ã½ —is to investigate and understand natural phenomena and educate our children and local population,” added Shea. “Only a small percentage of our local students are taught about Earth sciences in secondary schools statewide. Yet the coming decades pose formidable challenges in terms of hazards related to natural phenomena, not just volcanic eruptions at our four most active volcanoes (Kīlauea, Mauna Loa, Hualālai and Haleakalā) but coastal erosion, reef survival and climate change.”

A new volcano, Geldingadalir, has erupted in Iceland, offering rare opportunities for close-up exploration and research into eruption processes and how to better predict future eruptions. 60 Minutes correspondent Bill Whitaker talked with University of Â鶹´«Ã½ at Mānoa (SOEST) alumni Thorvaldur Thordarson and Christopher Hamilton, and Professor Bruce Houghton, during the eruption response.

Opportunity knocks

After a drastic decline in volcanic activity from the Halemaʻumaʻu lava lake on Kīlauea Volcano by April 2021 and with no access to the Italian volcano Stromboli during the COVID-19 pandemic, Houghton connected with Thordarson, who is now a professor in volcanology and petrology at the University of Iceland to find a new target for his research.

Given their robust working partnership and the dynamic and rapidly changing character of the eruption on the Reykjanes Peninsula in Iceland, the two researchers developed a plan to capture high resolution videos of the Reykjanes fountains to quantify the changing patterns of eruption style and strength and link this to drone-based studies of the evolving craters, lavas and cones.

When Houghton arrived at the volcano, he witnessed a spectacular sight.

“These were easily the best, most breath-taking fountaining eruptions that I have ever seen,” said Houghton. “Conditions were perfect for documenting their activity—we could approach safely to the very edge of any part of the system of linked lavas and cones and had driving access to many key observation points.”

Now back in Â鶹´«Ã½ with the video footage in hand, Houghton and UH researcher Caroline Tisdale will measure key parameters like eruption rate, particle sizes and velocities that determine the style and intensity of these unusual eruptions, which sit in the middle ground between Hawaiian lava fountains and short-lived explosions such as Stromboli.

The collaboration continues to provide new insights into the mechanisms affecting when, why and how basaltic volcanoes erupt. This information feeds directly into hazard and impact studies that are particularly important, in light of the 2018 eruptions and devastation at Kīlauea.

This event is an example of UH ²Ñā²Ô´Ç²¹â€™s goal of (PDF), one of four goals identified in the (PDF), updated in December 2020.

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–By Marcie Grabowski

The 2018 Kīlauea eruption in Â鶹´«Ã½ provided scientists with an unprecedented opportunity to identify new factors that could help forecast the hazard potential of future eruptions.

A team of researchers, including University of Â鶹´«Ã½ at Mānoa Professor Bruce Houghton, identified an indicator of magma viscosity that can be measured before an eruption, providing critical information to help understand possible future eruptions. The findings are .

“The study is very unusual because it falls at the interface between two distinct disciplines in volcanology: seismology and studies of the viscosity (fluidity) of the molten rock,” said Houghton.

Viscous magma linked with powerful explosions

The properties of the magma inside a volcano affect how an eruption will play out. In particular, the viscosity of this molten rock is a major factor in influencing how hazardous an eruption could be for nearby communities.

Very viscous magmas are linked with more powerful explosions because they can block gas from escaping through vents, allowing pressure to build up inside the volcano’s plumbing system. On the other hand, extrusion of more viscous magma results in slower-moving lava flows.

“But magma viscosity is usually only quantified well after an eruption, not in advance,” explained Diana Roman, lead author of the study and volcanologist at . “So, we are always trying to identify early indications of magma viscosity that could help forecast a volcano’s eruption style.”

Kīlauea eruption provides wealth of data

The 2018 event included the first eruptive activity in Kīlauea’s lower East Rift Zone since 1960. The first of 24 fissures opened in early May, and the eruption continued for three months. This situation provided unprecedented access to information for the team of researchers.

The event provided a wealth of simultaneous data about the behavior of both high- and low-viscosity magma, as well as about the pre-eruption stresses in the solid rock underlying Kīlauea.

Tectonic and volcanic activity cause fractures, called faults, to form in the rock that makes up Earth’s crust. When geologic stresses cause these faults to move against each other, geoscientists measure the 3-D orientation and movement of the faults using seismic instruments.

By studying what happened in Kīlauea’s lower East Rift Zone in 2018, Roman and her colleagues determined that the direction of the fault movements in the lower East Rift Zone before and during the volcanic eruption could be used to estimate the viscosity of rising magma during periods of precursory unrest.

“We were able to show that with robust monitoring we can relate pressure and stress in a volcano’s plumbing system to the underground movement of more viscous magma,” Roman explained. “This will enable monitoring experts to better anticipate the eruption behavior of volcanoes like Kīlauea and to tailor response strategies in advance.”

This research is an example of UH ²Ñā²Ô´Ç²¹â€™s goal of (PDF), one of four goals identified in the (PDF), updated in December 2020.

–By Marcie Grabowski

The unprecedented cost of the 2018 Kiīlauea eruption in Â鶹´«Ã½ reflects the intersection of distinct physical and social phenomena: infrequent, highly destructive eruptions and atypically high population growth, according to a new study published in and led by University of Â鶹´«Ã½ at Mānoa researchers.

It has long been recognized that areas in Puna, Â鶹´«Ã½, are at high risk from lava flows. In fact, Puna lies within the three highest-risk lava hazard zones (1, 2 and 3). This ensured that land values were lower, which actively promoted rapid population growth.

• Read more about ±«±á’s research on the 2018 KiÄ«lauea eruption.

“Low prices on beautiful land and a scarcity of recent eruptions led to unavoidable consequences—more people and more development,” said Bruce Houghton, the lead author of the study and Gordan Macdonald Professor of Volcanology in the UH Mānoa (SOEST). “Ultimately this drastically increased the value of what was at risk in 2018, relative to earlier eruptions of Kīlauea.”

Kīlauea is one of the most active volcanoes on Earth and has one of the earliest, most comprehensive volcanic monitoring systems. Its recent history has been dominated by activity at the summit caldera and from one of two lines of vents called the Eastern Rift Zone. Between 1967 and 2018, volcanic activity was dominated by eruptions from the upper part of the Eastern Rift Zone. In contrast, no damaging eruptions occurred after 1961 in the more heavily populated Puna district from the vents within the lower portion of the Eastern Rift Zone.

Assessing trends

The UH team assessed trends in population growth in Pāhoa-Kalapana, Hilo and Puna using census data, and compared the median cost of land and household income in these areas.

Valuable lessons regarding the complex interplay of science, policy and public behavior emerged from the 2018 disaster.

“Steep population growth occurred during the absence of any locally sourced eruptions between 1961 and 2018, and set the scene for the unprecedented levels of infrastructural damage during the 2018 Lower Eastern Rift Zone eruption,” said Wendy Cockshell, co-author on the paper and technical assistant at the (NDPTC) at UH Mānoa.

If population growth resumes in lava hazard zones 1 and 2, there will be increased risk in the most dangerous areas on this exceptionally active volcano translating into high cost of damage in future eruptions.

“Our funded research supports the principle of the initiatives by local and federal government to provide buy-out funding to landowners affected by the 2018 eruption to enable them to relocate outside of these hazardous areas,” said Houghton.

The study was funded with support from the National Science Foundation and the NDPTC.

This effort is an example of UH ²Ñā²Ô´Ç²¹â€™s goal of Excellence in (PDF), one of four goals identified in the (PDF), updated in December 2020.

–By Marcie Grabowski

The latest eruption that began late December 20, 2020, at Halemaʻumaʻu crater at the summit of Kīlauea on Â鶹´«Ã½ Island has fired up scientists, including three alumni. Armed with little sleep and a great education, the graduates are making important contributions.

Miki Warren (2018), Liliana DeSmither (2014) and Katie Mulliken (2012), work for the U.S. Geological Survey’s (USGS–HVO) and are currently helping with data collection and public communication.

DeSmither explained what she and Mulliken worked on during the first 18 hours of the eruption.

“Got a total of 2.5 hours of sleep last night,” DeSmither said. “Katie and I have been handling the [Volcano Activity Notice and Volcano Observatory Notice for Aviation] releases, helping to write, edit and review the information statement for the [magnitude 4.4] earthquake last night. We’ve also been getting updates, photos and videos from the field crews to write captions and post multimedia to the HVO webpage and responding to [emails sent to askHVO@usgs.gov]. Attended several meetings and calls about the eruption response and public facing information.”

DeSmither also created an animated image for the public showing the first several hours of the eruption using F1cam thermal camera images.

She and Mulliken are also geologists who work in the field.

Gas geochemistry

Warren’s specialty is gas geochemistry. She assists HVO scientists in collecting data on the types and amounts of volcanic gases that are emitted by the volcano, both during eruptions and times of inactivity. This work is critical for understanding how volcanoes work, and also for protecting the health of the general public.

Warren recalled her first night of the eruption, “I got a call from Tamar Elias, USGS–HVO gas geochemist, at 10:30 p.m. [the first night of the eruption]. I was on standby until I got the official word about half an hour later to head to the USGS–HVO warehouse in Kea‘au to pick up the gas team’s [Fourier-Transform Infrared Spectrometer] to bring to the summit of Kīlauea, where Halemaʻumaʻu was erupting. I went out with the gas team that night and collected geochemical spectral data using the light emitted from the new lava fountain in Halemaʻumaʻu. The next morning I came home and slept for two hours, then grabbed new sulfur dioxide sensors to see how much SO2 the lava was producing, and headed back to meet the HVO gas geochemists Tamar Elias and Tricia Nadeau for another full day of volcanic gas measurements.”

Center for the Study of Active Volcanoes

All three alumnae gained experience working around volcanic features, and monitoring eruptions of Kīlauea, while attending UH Hilo. Darcy Bevens, educational specialist at the UH Hilo (CSAV), said, “They acquired knowledge and skills, both from taking geology classes, and from working as student assistants with the Center for the .”

Bevens said the three geologists were hired at HVO through a UH Hilo , established by the late Senator Daniel K. Inouye in 1998 to promote research collaboration between HVO and UH Hilo, as well as an active natural hazards public outreach program to Â鶹´«Ã½ Island’s schools. The grant is managed by CSAV.

“Other cooperative projects include providing funding for equipment shared between HVO and UH Hilo,” said Bevens. “The UH Hilo geology department provides lab space and shares equipment with HVO, and students currently enrolled as geology majors enjoy working with HVO scientists on research projects.”

—By Susan Enright, a public information specialist for the Office of the Chancellor and editor of UH Hilo Stories.

The largest and hottest shield volcano on Earth was revealed by researchers from the University of Â鶹´«Ã½ at Mānoa (SOEST). In , a team of volcanologists and ocean explorers used several lines of evidence to determine Pūhāhonu, a volcano within the Papahānaumokuākea Marine National Monument, holds this distinction.

Geoscientists and the public have long thought Mauna Loa, a culturally-significant and active shield volcano on Â鶹´«Ã½ Island, was the largest volcano in the world. However, after surveying the ocean floor along the mostly submarine Hawaiian leeward volcano chain, chemically analyzing rocks in the UH Mānoa rock collection and modeling the results of these studies, the research team came to a new conclusion. Pūhāhonu, meaning “turtle rising for breath” in Hawaiian, is nearly twice as big as Mauna Loa.

“It has been proposed that hotspots that produce volcano chains like Â鶹´«Ã½ undergo progressive cooling over 1-2 million years and then die,” said Michael Garcia, lead author of the study and retired professor of at SOEST. “However, we have learned from this study that hotspots can undergo pulses of melt production. A small pulse created the Midway cluster of now extinct volcanoes and another, much bigger one created Pūhāhonu. This will rewrite the textbooks on how mantle plumes work.”

In 1974, Pūhāhonu (then called Gardner Pinnacles) was suspected to be the largest Hawaiian volcano based on very limited survey data. Subsequent studies of the Hawaiian Islands concluded that Mauna Loa was the largest volcano, but they included the root of the volcano that is below the seafloor that was not considered in the 1974 study. The new comprehensive surveying and modeling, using methods similar to those used for Mauna Loa, show that Pūhāhonu is the largest.

This study highlights Hawaiian volcanoes that have been erupting some of the hottest magma on Earth for millions of years.

For more information see the .

—By Marcie Grabowski