Most volcanism on Earth reflects plate-tectonic processes, occurring along the boundaries between the moving plates.
Volcanism occurring within plate interiors is instead typically explained by deep-rooted "plumes" that transport hot material upward to feed stationary "hotspots" of volcanism.
As the plate moves above them, these hotspots produce chains of volcanoes, such as the Hawaiian Islands. One volcano chain, with the exotic name "Pukapuka," submerged beneath the southeastern Pacific, lacks a characteristic hotspot feature: Its source of volcanism is not stationary.
Instead, it has been moving eastward rather quickly. By comparing computer simulations with ship-based observations of the chemistry, volumes, and ages of Pukapuka lavas, Ballmer and coauthors demonstrate a new mechanism for migrating intraplate volcanism.
They show that the massive injection of hot material by multiple plumes producing many of the Polynesian island chains also spreads out beneath the Pacific plate. As it spreads, it breaks up into multiple fingers, which melt at their tips to sustain volcanism.
The Pukapuka volcano chain is formed by one such finger, which has traversed the Pacific plate and recently emerged beneath the neighboring Nazca Plate.
These findings are important for understanding our planet's interior dynamics and how they produce volcanism.
Maxim D. Ballmer et al., Dept. of Geology and Geophysics, School of Ocean and Earth Sciences and Technology, University of Hawaii at Manoa,DOI:10.1130/G33804.1