PPT-Volcanoes

Vocabulary Crater bowlshaped formation at the top of a volcano Caldera large crater formed by the collapse of a volcano during a violent eruption Active Volcano a volcano that has erupted in the past 10000 years may be currently erupting and is expected to erupt again. 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.. 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?. 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!. Basaltic Lava – low silica content, low viscosity, low gas content. Hot spots – magma moves up from lower mantle and plates move over it . Ex. Hawaii. (note: see video on favorites). Shield Volcanoes. Martin . Ménégoz. , Francisco . Doblas. -Reyes, . Virginie. . Guemas. , . Asif. Muhammad. EC-Earth Meeting, Reading, May 2015. Reading, May 2015. 2. Introduction. Major eruptions bring large amounts (Tg) of particles in the stratosphere.. Target #16- I can summarize the conditions needed for magma to form. Despite the high temperature in the mantle, most of the layer remains solid due to extreme pressure. Magma: . liquid rock produced under Earth’s surface. 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”.. rd. graders. By Amy Zimmerman. what I hope my students learn…. What a volcano is.. Understand that there are 3 main types of volcanoes.. Understand the process of eruption. . Know all the different parts of a volcano.. 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 . Where are the major zones of volcanism?. What are the parts of a volcano?. How do volcanic landforms differ?. Copyright © McGraw-Hill Education. Volcanoes. Review. convergent. New. volcanism. hot spot. Romans believed in Vulcan, their god of fire.. They thought that Vulcan worked at a hot forge, striking sparks as he made swords and armor for the other gods.. Hawaiians told legends of the wanderings of Pele, their goddess of fire.. 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. 1. An opening in Earth’s crust through which molten rock, ash and gases erupt.. 2.Volcano: The landform that develops around the opening.. 3. A way for Earth to release heat energy from the interior due to radioactive decay.. What are volcanoes?. Does anyone know what a volcano is?. A volcano . is a landform (usually a mountain) where . liquid rock . erupts through the surface of the planet. .. The name "volcano" has its origin from the name of Vulcan, a god of fire in Roman mythology..