The four types of lava are basaltic, andesitic, dacitic and rhyolitic. Basaltic is further divided into pillow, a'a and pahoehoe lava. The primary difference among these types is the amount of silica they contain. Higher... More »

Four types of pyroclastic materials include ash, lapilli, lava blocks and floating rocks. Pyroclastic materials are ejected during a volcano. Ash is the most common type of pyroclastic material. More »

There are three main types of lava: a'a, pahoehoe and pillow lava. Each one flows at a different rate and has a different mineral composition. More »

There are three main types of lava: a'a, pahoehoe and pillow lava. Each one flows at a different rate and has a different mineral composition. More »

Volcanoes erupt to release pressure built up in the magma chamber by expelling the magma as lava. Along with lava, a volcanic eruption releases ash and greenhouse gases such as sulfur dioxide and carbon dioxide. More »

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Cinder cone volcanoes generally spew lava dramatically when they erupt, though the eruptions are not particularly dangerous to human populations. Dramatic and beautiful as the eruptions may be, they are quite insignifica... More »

The most common and serious types of volcanic hazards are flowing lava, falling ash, glowing avalanches and moving mud and debris. The exact hazard level varies depending on the type of volcano erupting. Additional hazar... More »

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