Volcanics

Volcanics is a term used in geology to describe the materials produced by volcanic activity and the processes by which they form. The study of volcanics includes volcanism, magma generation and ascent, eruption dynamics, and the resulting rocks and deposits that accumulate around volcanoes.

Magma originates in the mantle and rises due to buoyancy and gas pressure. Its viscosity, largely controlled by silica content and temperature, governs eruption style. Basaltic magma, with low viscosity, tends to erupt effusively, forming lava flows and shield-like volcanoes. Higher‑viscosity andesitic to rhyolitic magma traps gases and often drives explosive eruptions that eject ash plumes, pumice, and pyroclastic flows.

Volcanic products include lava flows, ash clouds, pumice, obsidian, lava domes, and various tephra deposits. Tephra ranges from fine ash to volcanic bombs and blocks. Volcanic activity also produces fumaroles, hot springs, and other hydrothermal features as the system adjusts to eruptive cycles.

Volcanism occurs in several tectonic settings, including subduction zones, mid-ocean ridges, and intraplate hotspots. Hazards associated with volcanics include ashfall that can affect aviation and health, lava flows, pyroclastic flows, lahars, and volcanic gases that can alter air quality and climate locally or globally.

Monitoring programs use seismology, ground deformation measurements, gas analysis, and satellite remote sensing to forecast eruptions and mitigate risks. Studying volcanics helps scientists understand planetary differentiation, crust formation, and the interaction between magmatic systems and surface environments. The volcanic record also informs hazard planning and land-use decisions in volcanic regions.