What is a volcano?

1. What is a volcano? A geological landform (usually a mountain) where magma (rock of the earth's interior made molten or liquid by high pressure and temperature) erupts through the surface of the planet. http://en.wikipedia.org

2. Most volcanoes on the land are formed at destructive plate margins: where oceanic crustis forced below the continental crust becauseoceanic crust is denser than continental crust. Friction between these moving plates will cause the oceanic crust to melt, and reduced density will force the newly formed magma to rise. As the magma rises through weak areas in the continental crust it may eventually erupt as one or more volcanoes. QUICK FACT: The study of volcanoes is called volcanology.

3. A volcano generally presents itself to the imagination as a mountain sending forth from its summit great clouds of smoke with vast sheets of flame. The truth is that a volcano seldom emits either smoke or flame, although various combinations of hydrogen, carbon, oxygen, and sulfur do sometimes ignite. What is mistaken for smoke consists of vast volumes of fine dust, mingled with steam and other vapors, chiefly sulfurous. Most of what appears to be flames is the glare from the erupting materials, glowing because of their high temperature; this glare reflects off the clouds of dust and steam, resembling fire. QUICK FACT: Volcanoes are described as active, dormant, or extinct.

4. Magma is molten rock often located inside a magma chamber beneath the surface of the Earth. Lava is found above the Earth's crust and magma is found below. Lava begins deep below the Earth's surface. This solid body of rock is called the mantle. Extreme pressure and heat melts rock and turns it into magma.  Magma pools together and forms a magma chamber. The magma pushes up towards the Earth's surface. QUICK FACT: Mt. Etna is Europe's highest volcano at 10,900 ft.

5. During an eruption, the magma is pushed up through a vent in a volcano. When it reaches the surface, it is called lava. The lava flows down the sides of the volcano. Even though lava is dangerous, it can flow very slowly. Lava is so hot that it burns everything in its path. QUICK FACT: The name "volcano" originates from the name of Vulcan, a god of fire in Roman mythology.

6. Shapes of Volcanoes: Shield volcano structure--Hawaii and Iceland are examples of places where volcanoes extrude huge quantities of lava that gradually build a wide mountain with a shield-like profile. Their lava flows are generally very hot and very fluid, contributing to long flows. Smaller versions of the "lava shield" include the 'lava dome' (tholoid), 'lava cone', and 'lava mound'. Volcanic cones or cinder cones result from eruptions that throw out mostly small pieces of rock that build up around the vent. QUICK FACT: Mr. Spock (Star Trek) was from the Planet Vulcan, not to be confused with Volcanology.

7. Shapes of Volcanoes: Stratovolcanoes or composite volcanoes are tall conical mountains composed of both lava flows and ejected material, which form the strata that give rise to the name. An examples is Mt. Fuji in Japan. Submarine volcanoes are common features on certain zones of the ocean floor. Some are active and, in shallow water, disclose their presence by blasting steam and rock-debris high above the surface of the sea. Many others lie at such great depths that the tremendous weight of the water above them results in high, confining pressure and prevents the formation and explosive release of steam and gases. QUICK FACT: Volcanoes are responsible for much of the land we live on, 90% of all the continents and ocean basins are the product of volcanism.

8. Mud volcanoes are formations which are often not associated with known magmatic activity. Active mud volcanoes tend to involve temperatures much lower than those of igneous volcanoes, except when a mud volcano is actually a vent of an igneous volcano. Igneous rocks are formed when molten rock (magma) cools and solidifies, with or without crystallization, either below the surface or on the surface. QUICK FACT: There are numerous volcanoes (some very active) on the solar system’s rocky planets and moons

9. Predicting Eruptions: Science has not yet been able to predict with absolute certainty when a volcanic eruption will take place, but significant progress in judging when one is probable has been made in recent time. Seismic activity (small earthquakes and tremors) always occurs as volcanoes awaken and prepare to erupt. Some volcanoes normally have continuing low-level seismic activity, but an increase can signify an eruption. The types of earthquakes that occur and where they start and end are also key signs. Volcanic seismicity has three major forms: short-period earthquakes, long-period earthquakes, and harmonic tremor. Listen to a Volcano erupting: Listen to an Earthquake:

10. Watch hot lava moving from within a volcano.

11. Witness a volcano throwing out hot molten lava.

12. Remember, the term Volcano has two definitions: 1. An opening in the crust of the Earth in which molten rock called magma and gases can escape to the surface. 2. The mountain that is formed from volcanic eruptions. Are you ready to learn more about volcanoes? Go to the ITU Web Site on Volcanoes and start your learning!

13. Resources Used: http://volcano.und.nodak.edu/vwdocs/vwlessons/lessons/Volcanoes/Volcanoes1.html http://en.wikipedia.org/wiki/Volcano http://www.soest.hawaii.edu/GG/hcv.html Thank you for your attention. Remember, learning can be fun!