PPT-Volcanoes Week 2 September 18

to September 22 1 Wk 2 Day 1 Before Question of the Day What 3 factors control the style of a volcanic eruptions During Notes After Exit Slip 2 Three Types of Volcanoes Shield Cone Composite. Lava Video. Volcanoes, magma, and lava. Volcanoes are weak spots in the crusts where molten material, or magma, comes to the surface.. When magma reaches the surface it is called lava.. The lava released during volcanic activity builds up Earth’s surface, it is a constructive force.. Chapter 5. Rigid Earth to Plate Tectonics. Learning Objectives. Know the different types of volcanoes and their associated features. Understand the relationship of the volcanoes to plate tectonics. Know what geographic regions are at risk from volcanoes. Frequency and Quantity. There are ~ 550 historically active volcanoes. About 60 erupt annually. The majority are 1) at the edge of continents and 2) underwater. Dormant volcanic cone in Japan. What causes volcanoes?. Gwen . Nytes. Composition. The magma in this type of volcano is made of basaltic-andesitic materials. The magma has an intermediate viscosity, so . it’s mildly explosive. It also consists of a lot of gases, so when the lava cools and hardens in the air, gas bubbles get trapped inside. The particles fall back down as cinders, and pile around the vent.. Yellowstone Park is not only spectacular but also unique. It is the result of three volcanic eruptions, the likes of which have never been seen in all of recorded history. The first eruption occurred 2 million years, followed by two more eruptions 1 million years and 600,000 years ago. Below Yellowstone Park there is a hot spot that is generating basaltic magma. At the time of each of their three eruptions, the magma chamber began to produce large volumes of basaltic magma. Because of its low viscosity, the basaltic magma quickly rose to the bottom of the granitic continental crust. However, because the density of basaltic magma (density about 3) is slightly higher than that of granite (density about 2.9) it could not force its way through the granite to the surface. Instead, it began to pool beneath the granitic crust. The amount of heat trapped within the molten basaltic magma was enough to melt the minerals making up the overlaying and surrounding granite, forming a growing mass of granitic magma. Granitic magma is highly viscous and extremely gas-charged. Although it rose only very slowly, the granitic magma advanced upwards by melting even more of its own overlying granitic rock. At some point, radial fractures began to form around the rising mass of granitic magma. These fractures allowed steam eruptions to vent gas. Shortly after, with the overlying granitic rock severely weakened by the fractures, the highly gas-charged granitic magma erupted. The land to a distance of 200 miles in all directions was decimated. Pyroclastic flows, the most destructive eruptive features known, swept across the countryside. Ash fell across the country from the eruption site to the Atlantic Ocean. Ash polluted the world’s atmosphere, blocked the energy of the Sun, and plunged the Northern Hemisphere into a frozen wasteland for years. Can such an eruption occur in the Yellowstone region again? All the evidence suggests that the magma chamber below Yellowstone Park is current rising. According to the director of the Yellowstone Volcanic Observatory, it is not a question of whether or not another super-eruption CAN happen; it’s a question of WHEN it will happen!. The Earths crust . The earths crust is in constant motion.. Volcanoes and earthquakes arise as sections of crust push . toghether. or pulled apart. Volcanoes and earthquakes are more common in certain parts of the world. By monitoring ground vibrations scientists can sometimes. Volcanism is mostly focused at plate margins. Pacific Ring of Fire. This map shows the margins of the Pacific tectonic plate and surrounding region. The red dots show the location of active volcanism. Notice how the majority of the volcanism is focused in lines along the plate boundaries? For this region is the area known as the “Pacific Ring of Fire”.. . T. his . is a map of Pompeii's famous volcano called . Mount . Vesuvius. . How many volcanoes are there in the . world?. There are around 1510 'active' volcanoes in the world. We currently know of 80 or more which are under the oceans. . VOLCANOES.. What is a volcano?. A volcano is a mountain that opens . below . to a pool of molten rock . called a magma chamber below . the surface of the earth. When . the pressure . builds up, eruptions take place. . What is a Volcano. Volcano: a weak spot in the crust where molten rock (magma) comes to the surface. Most volcanoes are located around subduction zones and hot spots. Over 75% of worlds volcanoes are found . Warm Up. Why do you think magma rises? Consider an ice cube floating at the top of a glass of water. Objective:. SWBAT. Describe at least two of the three types of volcanoes and how they form. Agenda:. Describe how the locations of volcanoes are related to plate tectonics.. Suggest why volcanoes are found at convergent and divergent plate boundaries.. Describe how . intraplate. volcanoes form.. Volcanic activity takes place primarily at . Compare the features of volcanoes.. Describe the stages in volcano formation.. What are Volcanoes?. Volcanoes are vents through which molten rock and gas escape from a . magma chamber.. Volcanoes can differ. Volcanoes. Volcano:. mountain that forms in Earth’s crust when molten material (magma) reaches the surface. . Remember, . magma . is molten rock below ground; . lava. is molten rock at the surface. .