Using a nearly 200-year record of lava chemistry from Kīlauea and Maunaloa, earth scientists from the University of Â鶹´«Ã½ at Mānoa and colleagues revealed that ±á²¹·É²¹¾±ʻ¾±â€™s two most active volcanoes share a source of magma within the Hawaiian plume. Their discovery was published in the .

“In the past, the distinct chemical compositions of lavas from Kīlauea and Maunaloa were thought to require completely separate magma pathways from the melt source in the mantle beneath each volcano to the surface where eruptions take place,” said Aaron Pietruszka, lead author of the study and associate professor in the in the UH Mānoa (SOEST). “Our latest research shows that this is incorrect. Melt from a shared mantle source within the Hawaiian plume may be transported alternately to Kīlauea or Maunaloa on a timescale of decades.”

From the mid-20th century to around 2010, Mauanloa was less active, whereas Kīlauea was highly active. During this time, the chemistry of lava from Kīlauea became more similar to typical lava from Maunaloa.

“We think this was caused by a change in the transport of mantle-derived melt from a shared source within the Hawaiian plume from Maunaloa to Kīlauea,” Pietruszka added. “In other words, each volcano iteratively becomes more active when it receives melt from the shared source in the mantle and this process causes measurable changes in lava chemistry.”

Since 2010, the research team has observed a change in lava chemistry at Kīlauea. This change suggests that melt from the shared source is now being diverted from Kīlauea to Maunaloa for the first time since the mid-20th century.

Maunaloa—the largest active volcano on Earth—erupted in 2022 after its longest known inactive period (~38 years). This eruptive hiatus at Maunaloa encompasses most of the ~35-year-long Puʻuʻōʻō eruption of neighboring Kīlauea, which ended in 2018 with a collapse of the summit caldera, an unusually large rift eruption, and lava fountains up to 260 feet tall.

The authors of the study emphasize that a long-term pattern of such opposite eruptive behavior suggests that a magmatic connection exists between these volcanoes. Additionally, this magmatic connection between Kīlauea and Maunaloa results in a broad correlation between changes in their lava chemistry.

“For example, during the late 19th century when Maunaloa was more active and Kīlauea was less active, the chemistry of lava from Kīlauea became more ‘unique’ and particular to compositions that are only observed at Kīlauea,” said Pietruszka. “We think this was caused by the transport of mantle-derived melt from the shared source of magma to Maunaloa.”

Forecasting future eruptions

Long-term forecasting of volcanic activity currently relies upon extrapolation of a volcano’s past eruption record.

“Our study suggests that monitoring of lava chemistry is a potential tool that may be used to forecast the eruption rate and frequency of these adjacent volcanoes on a timescale of decades,” Pietruszka said. “A future increase in eruptive activity at Maunaloa is likely if the chemistry of lava continues to change at Kīlauea.”

The researchers will continue to monitor the changes in lava chemistry at Kīlauea to determine whether their predictions for future changes in eruptive behavior at these volcanoes is correct.

–By Marcie Grabowski

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 .