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Where can we find volcanoes on earth?
Most volcanoes are found near subduction zones and mid-ocean ridges. This explains why the map of volcanoes on Earth matches
so well the map of tectonic plates. On the other hand, some volcanoes are located in remote places like in the middle of the Pacific plate (Hawaii), thousands of kilometres away from the
nearest plate boundary.
Main hazards from a quiet volcanic eruption is….Lava flow
Sometimes rising magma is blocked by horizontal layers of rock. The magma forces the layer of rock to bend upward into a landform called
Dome Mountain
Landforms From Lava and Ash• Composite Volcanoes have quiet eruptions
that alternate with explosive eruptions, forming layers of lava and ash.
Chapter 6 Volcanoes
Stages of Volcanic ActivityChapter 6 Volcanoes
• Extinct volcanoes are considered “dead” meaning that it is unlikely that they will erupt again
Stages of Volcanic ActivityChapter 6 Volcanoes
• Dormant volcanoes are considered “asleep” or “sleeping bears” meaning that they may become active in the future
Stages of Volcanic ActivityChapter 6 Volcanoes
• Active volcanoes are considered “live” meaning that it is erupting, or has shown signs that it may erupt in the near future
Magma Reaches Earth’s SurfaceChapter 6 Volcanoes
• Pyroclastic flow is an explosive eruption that includes hot gases, cinders (volcanic ash), and bombs (volcanic rocks).
Magma Reaches Earth’s SurfaceChapter 6 Volcanoes
• Aa is a very thick, slow moving lava. Aa contains high amounts of silica, which gives it it’s thickness. When aa hardens, it forms a rough surface consisting of jagged (sharp) lava chunks.
Magma Reaches Earth’s SurfaceChapter 6 Volcanoes
• Pahoehoe is a very thin, fast moving lava. Pahoehoe contains low amounts of silica, which gives it it’s thinness. When Pahoehoe hardens, it forms wrinkle and rope-like rock formations. Pahoehoe is hotter than Aa.
Magma Reaches Earth’s Surface• When a volcano
erupts, the force of the expanding gases pushes magma from the magma chamber through the pipe until it flows or explodes out of the vent.
Chapter 6 Volcanoes
Landforms From Lava and Ash• Calderas are formed when a magma chamber is
emptied after an eruption and the volcano mountain collapses into the empty space creating a crater.
Chapter 6 Volcanoes
Crater Lake, Oregon
Landforms From Lava and Ash• Lava Plateaus are formed from runny lava
(pahoehoe) that cools in flat sheets of rock. Over time these layers form high plateaus.
Chapter 6 Volcanoes
Steamboat Rock, Washington
Landforms From Lava and Ash• Cinder Cone Volcanoes have explosive
eruptions of ash, cinders, and bombs that form a cone-shaped hill.
Chapter 6 Volcanoes
Mount Etna, Italy