Contrary to longstanding geological assumptions, new research from the University of Hawai‘i at Mānoa reveals that the Hawaiian mantle plume—a massive upwelling of hot material beneath the Pacific plate—has increased in temperature by approximately 250°C over the past 47 million years. This groundbreaking discovery challenges the prevailing notion that mantle plumes cool progressively over time and suggests that the thermal dynamics of Earth’s interior are far more complex than previously believed.
The Hawaiian Ridge, a chain of 65 volcanoes extending over 3,500 kilometers, was formed as the Pacific tectonic plate migrated over this hotspot. Researchers led by Michael Garcia, Emeritus Professor of Earth Sciences at UH Mānoa’s School of Ocean and Earth Science and Technology, sought to understand the dramatic 100-fold variation in lava volume found along this volcanic chain. Their investigation focused on several potential explanations, including variations in lithospheric thickness, source magma composition, plate movement rate, and mantle plume temperature.
To address this challenge, the team analyzed olivine basalt samples from 16 volcanoes and employed a novel geothermometer—a cutting-edge computational tool designed to estimate the temperature at which the lava originated deep within the Earth’s mantle. By integrating these temperature estimates with comprehensive bathymetric and ocean floor data, researchers produced more precise assessments of volcanic size and growth patterns.
The results were striking: a direct correlation emerged between rising mantle temperatures and the size of Hawaiian volcanoes. Two distinct thermal surges were identified—one occurring between 14 and 20 million years ago, resulting in the formation of Pūhāhonu, the largest and longest-lived shield volcano in the last 60 million years, and another more recent surge between 0 and 6 million years ago responsible for the creation of the Main Hawaiian Islands.
This upward trend in mantle plume temperature overturns the conventional wisdom that these hotspots cool as they age. Instead, the findings suggest that dense, hot materials deep in the lowermost mantle may be drifting and accumulating beneath the Pacific plate, fueling these temperature increases. Such dynamics imply a previously unrecognized complexity in mantle convection and plume behavior.
Garcia emphasized the importance of the new geothermometer: “This tool opens a window into the thermal history of mantle plumes, allowing us to better understand why some volcanoes grow much larger than others.” The research not only reshapes our understanding of hotspot volcanism but also provides essential insights into the geological processes driving Earth’s surface evolution.
Published recently in Earth and Planetary Science Letters, this study combines state-of-the-art simulations with empirical geological investigations, highlighting the power of interdisciplinary science to challenge established paradigms. As Earth scientists continue to explore the deep mantle, these results pave the way for more precise models of volcanic formation and mantle dynamics that may extend beyond Hawai‘i.
The discovery underscores the dynamic and evolving nature of Earth’s interior and illustrates how mantle processes can have profound impacts on surface geology—effects that ripple through millions of years of volcanic activity to shape island chains and influence planetary geology worldwide.
Subject of Research: Hawaiian mantle plume temperature evolution and volcanic formation
Article Title: Earth and Planetary Science Letters
News Publication Date: 8-Jun-2026
Web References: http://dx.doi.org/10.1016/j.epsl.2026.120055
Image Credits: Garcia, et al., 2026
Keywords: Hawaiian mantle plume, volcano temperature, Pūhāhonu, shield volcano, mantle dynamics, hotspot volcanism, olivine basalt geothermometer, Pacific plate, volcanic ridge
