La Palma volcano magma study reveals superheating that drives explosive eruptions

Researchers analyzing near‑intact magma samples recovered from the 2021 Tajogaite eruption on La Palma have identified a superheating process that delays crystal formation in the magma. The elevated temperature prevents the usual nucleation of crystals, allowing the magma to remain highly fluid as it ascends, which can lead to explosive eruptions rather than effusive lava flows.

The study, involving teams from the University of Manchester, the Complutense University of Madrid, the University of La Laguna and the CSIC, used X‑ray micro‑tomography to reconstruct the three‑dimensional structure of the rocks at micrometer resolution. It also revealed a stratified magma reservoir with a cooler, water‑rich upper layer (≈1,065 °C) and a hotter, drier lower layer (≈1,135 °C). The findings suggest that magma can reactivate silently over a decade‑plus, challenging traditional volcanic monitoring models that rely on seismic signals alone.

The erupted material was identified as tephritic magma, a “child” magma that has evolved over thousands of years in the upper mantle and lower crust, consistent with the composition of historic eruptions on the island.