Presentation on theme: "Volcanoes 2 Cyamaba Volcano, Ecuador. Learning Goals Learn about the role of plate tectonics in causing volcanoes and learn what causes eruptions to be."— Presentation transcript:
Learning Goals Learn about the role of plate tectonics in causing volcanoes and learn what causes eruptions to be gentle or highly explosive. Identify the main types of volcanoes: shield volcanoes, stratovolcanoes, and cinder cones. Learn about other forms of volcanic activity such as geysers, hot springs, hydrothermal vents, and geothermal energy.
Vocabulary Terms caldera cinder cone volcano crater geothermal energy hydrothermal vent lava magma magma chamber Ring of Fire rock cycle shield volcano stratovolcano vent
Volcanoes The eruption of Mount St. Helens in 1980 reduced the height of this mountain from 2,932 meters (9,677 feet) to 2,535 meters (8,364 feet). Early in the morning of May 18, 1980, an earthquake triggered a landslide that caused the bulge to eject magma, water, and gases.
Volcanoes Lava viscosity also determines how explosive an eruption will be. Explosive eruptions occur when the lava has a lot of water and dissolved gases. Gentle eruptions are associated with fast-flowing lava from oceanic crust.
Volcanoes Volcanoes also form when an oceanic plate slides under another oceanic plate.
Hydrothermal Vents Hydrothermal vents are deep sea, chimney-like structures that occur along midocean ridges.
Volcanoes Some gemstones are also associated with volcanic activity. For example, diamonds form at high temperatures deep underground when carbon crystallizes inside rocks called kimberlites.
Volcanoes Geothermal energy is the useful product of volcanic activity. When steam from magma collects below ground, it can be tapped just like water in a well. The pressurized steam can be used to generate electricity.
Volcanoes Volcanic activity results in the formation of two kinds of igneous rocks: — extrusive — intrusive A batholith is a large underground rock that formed when a mass of magma cooled underground.
Volcanoes Key Question: Why do some volcanoes erupt explosively?