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Volcano Calendar 2019
: We're proud to present our 2019 volcano calendar: 13 different and attractive images of volcanoes, volcanic landscapes and phenomena taken during volcano tours over the past few years.
: Depuis 2005, VolcanoDiscovery propose des voyages en petits groupes, des randonnées et du trekking, ainsi que des expéditions pour voir des volcans actuellement en activité, des voyages photographiques dans de nombreuses régions d’activité volcanique à travers le monde.
Livre Volcano Adventure Guide
: Excellente information et historique verser tous ceux qui veulent visiter les volcans actifs et agreable en toute curit. Le livre prentente des lignes directrices de la visite de 42 diff loue des volcans dans le monde entier.
: Places libres / : Départ garanti / : Quelques places disponibles / : Groupe fermé
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Glossaire illustré de la volcanologie
Volcanology: pierre ponce
Our tour guide Marta posing in Lipari's pumice...
Pumice from the Greek island Santorini
Un très léger, habituellement brillant en couleur, écume roche volcanique formé par la lave solidifiée visqueux, contenant de nombreuses bulles de gaz.
Pumice is a textural term for a volcanic rock that is a solidified frothy lava composed of highly microvesicular glass pyroclastic with very thin, translucent bubble walls of extrusive igneous rock. It is commonly, but not exclusively of silicic or felsic to intermediate in composition (e.g. rhyolitic, dacitic, andesite, pantellerite, phonolite, trachyte), but occurrences of basaltic and other compositions are known. Pumice is commonly pale in color, ranging from white, cream or grey, but can be green brown or black. It forms when gases exsolving from viscous magma nucleate bubbles which cannot readily decouple from the viscous magma prior to chilling to glass. Pumice is a common product of explosive eruptions (plinian and ignimbrite-forming) and commonly forms zones in upper parts of silicic lavas. Pumice has an average porosity of 90%, and initially floats on water.
Scoria differs from pumice in being denser, with larger vesicles and thicker vesicle walls; it sinks rapidly. The difference is the result of the lower viscosity of the magma that formed scoria. When larger amounts of gas are present, the result is a finer-grained variety of pumice known as pumicite. Pumice is considered a glass because it has no crystal structure. Pumice varies in density according to the thickness of the solid material between the bubbles; many samples float in water. After the explosion of Krakatoa, rafts of pumice drifted through the Pacific Ocean for up to 20 years, with tree trunks floating among them. In fact, pumice rafts disperse and support several marine species. In 1979, 1984 and 2006, underwater volcanic eruptions near Tonga created large pumice rafts, some as large as 30 km that floated hundreds of miles to Fiji.
Famous pumice deposits in Europe include Lipari Island (Italy), Santorini and Yali (Greece), as well as the Laacher See (Germany).
Plus sur VolcanoDiscovery:
Dallol hot springs
: One of the most bizarre landscapes on earth: Dallol is a vast and very active hydrothermal field creating a colorful array of hot springs, small geysers, salt towers, colorful lakes and ponds in the middle of the deepest part of the Danakil desert and the Karum salt lake.
: Lists and maps of earthquakes in the world in near real time. Country lists, earthquake archive, and I-felt-it reports.
Les volcans actifs de la Chine
: Did you know that there are at least 15 active volcanoes in China? The last eruption was from the Kunlun volcano in 1951.