A team of Earth scientists from the University of Hawai’i at Mānoa, along with international collaborators, has recently made an exciting discovery regarding the magma sources of Hawai’i’s two most active volcanoes: Kīlauea and Mauna Loa. Published in the Journal of Petrology, their research shows that these volcanoes share a common magma source within the Hawaiian plume—a finding that challenges long-standing beliefs about the independent origins of lava chemistry at these two volcanoes. The results have significant implications for understanding volcanic behavior and could pave the way for more accurate eruption forecasting.
Challenging Old Assumptions
For many years, scientists thought that the distinct chemical compositions of the lava erupted by Kīlauea and Mauna Loa indicated completely separate pathways for magma from the mantle to the surface. This would imply that each volcano had its own independent source of magma, transported through distinct conduits beneath the Earth’s surface. However, the latest research, led by Aaron Pietruszka, an associate professor in the Department of Earth Sciences at UH Mānoa’s School of Ocean and Earth Science and Technology (SOEST), contradicts this view.
“In the past, we thought that the distinct chemical compositions of lavas from Kīlauea and Mauna Loa required completely separate magma pathways,” Pietruszka explains. “Our new research shows that this is not the case. Instead, both volcanoes draw their magma from a shared mantle source within the Hawaiian plume, and melt from this source can be alternately transported to Kīlauea or Mauna Loa on a timescale of decades.”
Lava Chemistry as a Clue to Magmatic Connection
Kīlauea and Mauna Loa are two of the most active volcanoes in the world, and they have exhibited highly variable eruptive behaviors over the past century. In particular, Mauna Loa, the largest active volcano on Earth, erupted in 2022 after its longest known period of dormancy (approximately 38 years). This long period of inactivity overlapped with the nearly continuous Puʻuʻōʻō eruption of neighboring Kīlauea, which lasted for about 35 years, from 1983 to 2018. The eruption ended with significant events such as the collapse of Kīlauea’s summit caldera, large rift eruptions, and impressive lava fountains reaching up to 260 feet.
The long-term contrasting eruptive patterns of these two volcanoes—one becoming highly active while the other remains dormant for extended periods—prompted the research team to investigate whether there might be a connection between their magma sources. Their findings suggest that there is indeed a magmatic connection that explains this alternating behavior.
A Closer Look at Lava Chemistry
By analyzing a near 200-year record of lava chemistry from both volcanoes, the researchers found evidence that changes in lava composition correlate with periods of increased or decreased volcanic activity at both Kīlauea and Mauna Loa.
For example, in the late 19th century, Mauna Loa was more active, and Kīlauea was relatively dormant. During this time, the lava chemistry of Kīlauea became more “unique,” deviating from the typical compositions seen at Mauna Loa. The researchers propose that this shift in Kīlauea’s lava chemistry was likely due to magma being transported from the shared source to Mauna Loa, leaving Kīlauea with a reduced supply of melt.
Conversely, from the mid-20th century to around 2010, Mauna Loa was less active, while Kīlauea became highly active. During this period, the lava chemistry at Kīlauea shifted again, becoming more similar to that of Mauna Loa. Pietruszka and his colleagues suggest that this change in lava chemistry was due to the transport of mantle-derived melt from the Hawaiian plume, now directed more towards Kīlauea.
A New Era of Lava Chemistry at Kīlauea
More recently, since around 2010, scientists have observed another shift in the lava chemistry at Kīlauea. The chemistry of the lava has begun to change once again, signaling that magma is now being diverted away from Kīlauea and toward Mauna Loa for the first time in several decades. This observation supports the idea that the magmatic connection between Kīlauea and Mauna Loa is not static but instead operates in a dynamic, alternating pattern.
This shift in lava chemistry is significant because it suggests that Mauna Loa may be entering a phase of increased activity, potentially signaling a future eruption. The research team is closely monitoring these changes in lava composition to determine whether this pattern will continue and whether it can be used to predict future volcanic behavior at both volcanoes.
Implications for Volcanic Forecasting
One of the most promising aspects of this study is its potential application to volcanic eruption forecasting. Currently, long-term predictions of volcanic activity are largely based on the historical eruption records of individual volcanoes. However, this research suggests that changes in lava chemistry could provide an additional, valuable tool for forecasting future eruptions.
Pietruszka notes, “Our study suggests that monitoring lava chemistry could be used as a tool to forecast the eruption rate and frequency of these adjacent volcanoes on a timescale of decades. If the chemistry of lava at Kīlauea continues to change in the way we’ve observed, we expect to see an increase in eruptive activity at Mauna Loa.”
By understanding the patterns of lava chemistry and how they correspond to shifts in magma transport between Kīlauea and Mauna Loa, scientists may be able to improve their predictions about when and where eruptions are likely to occur. This could be crucial for informing emergency response strategies and minimizing the risks posed by these dynamic volcanoes.
Conclusion
The discovery of a shared magma source between Kīlauea and Mauna Loa represents a significant shift in our understanding of the dynamics of Hawaiian volcanoes. By studying changes in the chemistry of lava over time, scientists have uncovered a pattern of magmatic transport that alternately favors one volcano over the other, explaining the observed periods of intense activity at Kīlauea and Mauna Loa.
This new perspective on the connection between Kīlauea and Mauna Loa opens up exciting possibilities for future research and volcanic hazard forecasting. By continuing to monitor lava chemistry, researchers will gain deeper insights into the behavior of these two colossal volcanoes and refine their ability to predict future eruptions. The study not only advances our understanding of Hawaiian volcanism but also offers a broader model for the behavior of other volcanic systems around the world.
Reference: Aaron J Pietruszka et al, Awakening of Maunaloa Linked to Melt Shared from Kīlauea’s Mantle Source, Journal of Petrology (2024). DOI: 10.1093/petrology/egae121