Volcanic Processes

Volcanic Processes — page 1 — explosive earth When you think of a volcano what do you picture in your mind Most people would say they see a large gray mountain spitting out red streams of lava and huge clouds of smoke However this is just one type of volcano Volcanoes can take different forms and behave in different ways Vocabulary A volcano is an opening in Earth’s crust Lava gas and ashes come out of the opening This is an eruption of the volcano Tungurahua in Ecuador The fiery streams of lava it is spewing out are just one type of volcanic eruption 4

Volcanic Processes — page 2 — Some volcanic eruptions like this one in Indonesia release mainly gas and ashes The moment when material comes out from an opening in Earth’s surface is called an eruption This is the part of the volcanic process that we can observe However there are many things that happen underground before the eruption Earth looks and feels solid to us here on the surface However the planet is actually always changing Pieces of Earth’s solid rocky surface shift Some pieces rise up while others settle down As rock moves deep underground it sometimes becomes molten or melted and rises up to the surface Once it comes out it cools and hardens making new rock 5

Volcanic Processes — page 3 — BENEATH THE SURFACE gas and ash cloud falling ash Deep under Earth's surface it can be very hot The temperature is so high that it can melt rock This melted rock is called magma Magma is located deep below Earth's surface It forms in the lower part of the planet's crust and in the upper part of the planet's mantle The mantle is the layer of Earth that lies beneath the planet's solid crust and above the core Inside View of an Erupting Volcano crater side vent main vent lava flow layers of ash and lava As magma heats up it rises Gas bubbles form and grow The gas makes the magma rise faster until it breaks through the

Volcanic Processes — page 4 — The three layers of Earth are the core the mantle and the crust The crust is the thinnest layer mantle 1 800 miles core 4 300 miles crust 3 19 miles If the magma cools it turns back into solid rock However if the magma continues to heat up it begins to rise It may slip through cracks in Earth's surface Sometimes it collects in a space called a magma chamber As the magma rises gas bubbles are made As they grow they make the magma move up faster Pressure builds and builds and the magma keeps rising until it breaks through the surface Once it reaches the surface magma is called lava 2014 Encyclopædia Britannica Inc COMPARE AND CONTRAST How are magma and lava the same What is the difference between

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