Eruptions

Eruptions are the sudden release of material from a confined source, driven by internal pressure, temperature, or chemical reactions. They occur in natural systems where gas-rich magma or heated fluids accumulate and find a path to the surface. The most studied eruptions are volcanic, but eruptions also occur in geysers, hot springs, and other geothermal systems.

In volcanology, eruptions are influenced by magma viscosity, gas content, and chamber pressure. When volatiles exsolve as magma rises and pressure drops, gases form bubbles that contribute to fragmentation. Eruptions are commonly classified as effusive, which emit lava flows, or explosive, which eject ash, pumice, and various tephra. Precursors include swarm seismicity, ground deformation, and increasing gas emissions, and monitoring uses seismographs, satellite imagery, and gas measurements.

Standard eruption styles include Strombolian (moderate, periodic bursts of incandescent bombs), Vulcanian (violent, ash-rich explosions with block ejection), and Plinian (large, sustained columns with widespread tephra). Phreatic eruptions are steam-driven and often involve rapid heating of groundwater without fresh magma.

Impacts range from lava flows and ash fall to pyroclastic surges, tsunamis, and climate effects from aerosols. Air travel can be disrupted by ash clouds. Nearby populations face hazards from ballistic ejecta, landslides, and contaminated water.

Notable eruptions include Mount Vesuvius in 79 CE, Krakatoa in 1883, Mount St. Helens in 1980, and Eyjafjallajökull in 2010. Long-term monitoring and research aim to forecast eruptions and mitigate risks through alerts, evacuations, and land-use planning.