Vulkáni

Vulkáni are geological features where magma from Earth's mantle reaches the surface. They form at plate boundaries and, less commonly, above hotspots. The composition of the erupted magma determines their shape and behavior. Low-viscosity magmas (basalt) tend to build broad, gently sloping shield volcanoes; higher-viscosity magmas (andesitic to rhyolitic) tend to form steep, layered stratovolcanoes. Smaller cinder cones arise from tephra eruptions, and calderas form after magma chamber collapse.

Eruptions range from effusive lava flows to explosive outbursts that eject ash clouds, pumice, and volcanic bombs. Common eruption styles include Hawaiian (lava fountains and lava flows), Strombolian and Vulcanian (tephra explosions), and Plinian (vigorous ash plumes). Gas emissions can be significant and influence climate and air quality.

Hazards associated with vulkáni include lava flows that burn or bury structures, pyroclastic flows that devastate everything in their path, ash fall that affects aviation and health, and lahars generated by melted ice or heavy rainfall. Volcanic gases such as sulfur dioxide can affect air quality over wide areas.

Monitoring and research rely on seismographs, deformation measurements, gas sensors, and satellite observations. Early warning systems, hazard maps, and public education reduce risk in populated regions around volcanoes.

Notable examples include Mauna Loa and Kilauea in Hawaii, Mount Etna in Italy, Mount Vesuvius in Italy, Eyjafjallajökull in Iceland, Krakatoa in Indonesia, and Mount Pinatubo in the Philippines. Volcanoes continually reshape landscapes and contribute to Earth's geochemical cycles.