Unlocking the Secrets Beneath Hawai’i’s Volcanoes
Above: Kīlauea volcanic eruption in 2025 Credit: USGS
THE FIRE AND FURY OF HAWAI‘I’S VOLCANOES are more than awe-inspiring natural wonders — they are living laboratories, constantly offering clues about the inner workings of Earth’s interior.
As a volcanologist with a passion for both the science and the art of lava, Department of Earth Sciences Associate Professor Aaron Pietruszka of the University of Hawai‘i at Mānoa’s School of Ocean and Earth Sciences and Technology has made a name for himself in the world of geochemistry by studying the active flows of Kīlauea and Mauna Loa volcanoes on Hawai‘i Island, and Kama‘ehuakanaloa (formerly Lō‘ihi), forming to the south of the island.
Pietruszka’s research focuses on the chemical composition of lava, which serves as a time capsule, offering rare insights into the planet’s volcanic plumbing system — how magma forms, moves and erupts from deep within Earth’s mantle up to the island’s surface.
His latest groundbreaking discovery challenges one of the most entrenched ideas in Hawaiian volcanology: that Mauna Loa and Kīlauea draw from separate magma sources. Instead, his research reveals the opposite — that despite clear differences in the composition of their lavas, both volcanoes display remarkably similar geochemical patterns over time. This unexpected connection is offering scientists a new lens to study volcanic behavior on Hawai‘i Island, and possibly forecast its activity.
Following Lava’s Chemical Trail
Pietruszka and his team study how molten rock evolves from the depths of the Earth to the moment it erupts. Their method relies on analyzing the chemical composition of lava — both major elements like iron and silicon, as well as trace elements such as strontium, lanthanum, barium, and lead. They also measure each element’s isotope ratios, which act like a unique fingerprint of each lava sample, revealing its origin and journey.
These chemical records provide a detailed timeline of volcanic activity. For example, Kīlauea’s lava has been chemically tracked back over 1,000 years, offering a rare glimpse into how volcanic systems evolve. Through this analysis, Pietruszka investigates key processes within the so-called “magma plumbing system” to determine how magma melts in the mantle, accumulates in chambers, and moves through intermediate layers before erupting. It provides a step-by-step chemical map from Earth’s interior to its surface.
A Surprising Relationship
This chemical map that Pietruszka and his team had developed led to a surprising discovery — that Mauna Loa and Kīlauea actually share the same magma source, challenging a decades-long theory of traditional geologists.
“What we found was a shared pattern of compositional change over time between the two volcanoes, which was surprising,” said Pietruszka. “These synchronized fluctuations likely reflect changes in how magma melts and rises through the mantle plume, not necessarily differences in source material.”
His team found that even though their lavas are distinct, similar trends suggest the two systems may be influenced by a deeper, connected supply zone — a hypothesis supported by geophysical observations, including seismic data that hint at physical connections underground.
Rare Insights from Hawai‘i
This discovery was made possible because Hawai‘i is one of the few places on Earth where such fine-scale geochemical records are possible. Because Hawai‘i’s volcanoes are intraplate (formed far from tectonic boundaries) and associated with a hotspot, they tend to erupt more frequently and produce high volumes of magma, allowing researchers to sample lava flows often, tracking changes over months, years, and even centuries.
“Hawai‘i Island’s volcanoes give us a rare chance to observe short-term changes in lava chemistry, unlike volcanoes in subduction zones — like those in Guatemala, Italy, or the Indian Ocean — which erupt less frequently and are harder to study in such detail,” said Pietruszka.
The Next Big Question
A next major research frontier for Pietruszka is understanding what happens beneath Kīlauea when its summit collapses — a phenomenon last observed during the 2018 eruption, which dramatically reshaped the landscape and highlighted how hazardous these events can be.
“We know Kīlauea’s summit has collapsed multiple times in the past, but we still don’t fully understand what controls the timing or mechanics of those collapses,” said Pietruszka. “These caldera-forming events are explosive and can be dangerous, so we want to know what triggers them and what conditions make them more likely.”
To answer those questions, Pietruszka is currently developing a multi-year research project focused on caldera formation and collapse processes. The goal: to understand what causes these massive structural failures and whether any signals can be used to anticipate them.
Science Meets Art
Since taking a printmaking class, Pietruszka has started translating his volcanic studies into visual art, featuring images of magma chambers, subduction zones, erupting lava, and his recent discovery of the shared magma chambers of Kīlauea and Mauna Loa.
“It’s another way of communicating what’s happening beneath our feet,” said Pietruszka. “We’ve used it as an education tool in classrooms, lectures and public outreach to spark conversations about how people and the built environment interact with natural hazards like volcanoes.”
Improving Forecasts
While volcanic eruptions remain difficult to predict, Pietruszka’s research is laying the groundwork for better forecasting. By tracking lava chemistry through real-time sampling of active eruptions in collaboration with the Hawaiian Volcano Observatory and National Park Service, Pietruszka and his team are beginning to understand the tempo of a volcano — how quickly its plumbing changes, and how that might relate to future eruptions.
“If we can better understand how volcanoes work —how they behaved in the past and how they’re changing in real time — we can improve our ability to forecast eruptions and better prepare and protect our communities. With thousands of residents living on the slopes of active volcanoes like Kīlauea, Mauna Loa, and Hualālai, this knowledge isn’t just academic, it’s a lifeline.”