Volcanic degassing

thumb|upright=1.5|Fresh lava from Fagradalsfjall volcano eruption in Iceland, 2023 Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or underwater, usually at temperatures from . Lava may be erupted directly onto the land surface or onto the sea floor or it may be ejected into the atmosphere before falling back down. The solid volcanic rock resulting from subsequent cooling of the molten material is often also ca

gases given off by active volcanoes

cloud of ash and tephra released during an explosive volcanic eruption

thumb|Mofetta with gas bubbles in Soos National Nature Reserve near Skalná, Czech Republic thumb|Mofettas on the southeastern shore of the Laacher See, near [[Andernach, Rhineland-Palatinate, Germany]] Mofetta (Italian from Latin mephītis, a pestilential exhalation) is a name applied to a volcanic discharge consisting chiefly of carbon dioxide, often associated with other vapours, representing the final phase of volcanic activity. The Oxford Dictionary of English lists mofetta as an archaic term for the modern word fumarole.

thumb|Dense vog as seen from Hilo Bay, Hawaii Vog is a form of air pollution that results when sulfur dioxide and other gases and particles emitted by an erupting volcano react with oxygen and moisture in the presence of sunlight. The word is a portmanteau of the words volcanic and smog, the latter itself a portmanteau of smoke and fog. The term is in common use in the Hawaiian Islands, where the Kīlauea volcano, on the Island of Hawaii (the "Big Island"), erupted continuously between 1983 and 2018. Based on June 2008 measurements, Kīlauea emits 2,000–4,000 tons of sulfur dioxide (SO2) every d

large expanse of nearly flat-lying lava flows

thumb|Mudpot in Lassen Volcanic National Park thumb|Mudpots lined up above a volcanic fissure at Krafla|Hverarönd, [[Iceland]]

optical phenomenon resulting from burning sulfur

thumb|Mazuku forming in a low morphological depression on the foothills of Mt. Amiata, Italy, where CO2-rich fog accumulates in a ditch Mazuku (Swahili for "evil winds") are pockets of dry, cold carbon dioxide-rich gases released from vents or fissures in volcanically and tectonically active areas, mixed with dispersed atmospheric air and accumulating in typically low-lying areas. Since carbon dioxide (CO2) is ~1.5 times heavier than air, it tends to flow downhill, hugging the ground like a low fog and gathering in enclosed spaces with poor ventilation—such as lava tubes, ditches, depressions,