Superheated magma can alter eruption dynamics by dissolving the microscopic crystal seeds that normally initiate solidification, researchers say. Analysis of material from the 2021 Tajogaite eruption on La Palma indicates that when melt reaches sufficiently high temperatures these seed crystals disappear, allowing the molten rock to remain fluid during rapid ascent. That persistence of a low-viscosity melt provides a plausible physical mechanism for sustained, towering lava fountains observed during the event.
The process targets the tiny nuclei around which crystals grow. In typical magmas, these nuclei trigger crystallization as the magma cools or decompresses during ascent, increasing viscosity and hindering gas expansion. The new findings show that at elevated temperatures the nuclei are soluble and can be erased before crystallization begins. Without those seeds, the melt can ascend farther before solidifying, maintaining fluid properties that influence eruption style and ejecta dynamics.
Scientists reached these conclusions after examining erupted material and textural evidence from the Tajogaite flow fields. Mineral textures, melt compositions and the distribution of microlite crystals point to a period in which melt temperatures were high enough to dissolve early-formed crystals. The study links those petrological observations to observed eruptive behavior, providing a coherent account of how thermal conditions within the magma reservoir and conduit can shift an eruption toward more fountain-dominated activity.
The results refine understanding of the physical controls on explosive versus effusive behaviour in basaltic systems. By highlighting the role of temperature in suppressing nucleation and delaying crystallization, the research offers a testable mechanism for why some eruptions produce long-lived fountains while others do not. These insights contribute to volcanology by connecting small-scale mineral processes to large-scale eruption phenomena and may inform future efforts to interpret monitoring data from similarly active volcanoes.
