Transcript Volcano
How many active volcanoes are in the world? About 1500 Begin volcano video and questions Pick one way to trigger a tsunami (1) ◦ Include one real life example (1) Describe how a tsunami wave is different from a wind wave (2) Describe at least three ways the tsunami causes destruction (3) Describe at least three ways to increase your chances of survival during the tsunami (3) Include at least two pictures or drawings (2) http://www.pbs.org/wgbh/nova/earth/deadli est-volcanoes.html 1. 2. 3. 4. 5. 6. 7. 8. What triggers volcanic eruptions? What is an ash cloud and how can it impact the world? How is Yellowstone a super volcano if it’s not on a plate boundary? How are cosmic rays used to investigate volcanoes? Why is the ground in Naples moving up? What can the different volcanic gases tell us about upcoming volcanic eruptions? What is a “Lahar”, how are they created, and why are they dangerous? Can we do anything but hope these dangerous volcanoes don’t erupt soon? Tsunami Questions Volcano quiz Final exam is next Thursday, 6/5 (20%) ◦ 50MC questions ◦ Open notebook Astronomy (quiz?) Safety Video Due 6/13 Groups of up to 4 Nothing illegal 4 minutes (including intro, video, outtakes, and credits) Printed list of proper safety procedures 1. 2. 3. What is an ash cloud and how can it impact the world? What can the different volcanic gases tell us about upcoming volcanic eruptions? Can we do anything but hope these dangerous volcanoes don’t erupt soon? Know where and why volcanoes form. Know the different features and types of volcanoes. A rupture on the crust which allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. Generally found at convergent and divergent plate boundaries. Also found at “hot spots”, located above mantle plumes. ◦ Where magma rises to the surface 1. 2. What is a volcano? What are three types of places where volcanoes are commonly found? Thin crust from the spreading boundary Release in pressure Magma rises and forms new rock The center of the ridge is new rock from rising magma Not a line of typical volcanoes “Black Smokers”: Deep sea vents where the magma rises and cools to become ocean floor Iceland is part of the ridge that is above sea level. https://www.youtube.com/watch?v=y6iK19x aYJg Usually between an oceanic plate and a continental plate The oceanic plate becomes magma as it is run over by the continental plate This magma tends to be very viscous and cools at depth before reaching the surface When it does reach the surface it creates a volcano https: //ww w.yo utube .com /watc h?v=I t710 7ELQ vY Name given to areas believed to be formed by mantle plumes. ◦ Columns of hot material rising from the coremantle boundary in a fixed space https://www.youtube.com/watch?v=g7OTVU Y_PdQ Start 3:40 1. 2. 3. Where does the magma come from at a divergent boundary? Where does the magma come from at a convergent boundary? Where does the magma come from at a hotspot? Volcanoes are described by their different features. Volcanic fissure vents are flat, linear cracks through which lava emerges. https://www.youtub e.com/watch?v=VG 3YunIcZ54 Built by slow eruptions of highly viscous lava They are sometimes formed within the crater of a previous volcanic eruption (Mt. St. Helen) Can produce violent, explosive eruptions Generally lava does not flow far from the originating vent. 1. What is a fissure vent? 2. How is a lava dome formed? 3. Why are lava domes dangerous? 1. 2. 3. Shield Cinder Cone Composite (Stratovolcanoes) Broad shield-like profile Formed by the eruption of low-viscosity (watery) lava that can flow a great distance from a vent. Generally don’t explode catastrophically Hawaii is a chain of shield cones Common in Iceland as well 1. How are shield volcanoes formed? Result from eruptions of small cinders Short-lived eruptions Produce a cone-shaped hill 30 to 400 meters high Most only erupt once May form off side of larger volcanoes Based on satellite images they might occur on other terrestrial bodies in our solar system 1. How are shield volcanoes formed? 2. What are cinder cones the result of? Tall conical mountains composed of lava flows and other ejecta in alternate layers. Different layers are made of cinders, ash, and lava. Cinders and ash pile on top of each other, lava flows on top of the ash, where it cools and hardens, and then the process repeats. Greater pressure build up than shield volcanoes from the underlying lava flow More powerful eruptions from fissure vents and cones Steeper than shield volcanoes Ash produced from these have posed the greatest volcanic hazard to civilizations. 1. How are shield volcanoes formed? 2. What are cinder cones the result of? 3. How do the different layers of a strato/composite volcano form? 1. 2. 3. Supervolcanoes Submarine Volcanoes Subglacial Volcanoes Another way of classifying volcanoes is by the composition of lava Lava can be broadly classified into 4 different compositions. Two ways Smart Way: Wait for it to cool, pick it up, bring it to a lab for testing. Not So Smart Way: Get it while it’s hot! ◦ https://www.youtube.com/watch?v=egEGaBXG3Kg ◦ http://petapixel.com/2014/05/28/swimming-fire-btsvideo-qa-two-daredevil-lava-photographers/ Erupted magma contains >63% of silica Highly viscous (not very fluid) ◦ Not vicious (spiteful) Trap gases which cause violent eruptions Erupted magma contains 52-63% silica Generally occur above subduction zones ◦ Typically formed at convergent boundaries Intermediate because the magma is a mixing between felsic and mafic magmas. Erupted magma contains 45-52% silica Tend to be hotter and less viscous than felsic lavas. Occur in a wide range of settings: ◦ Mid-ocean ridges ◦ Shield volcanoes ◦ Continental flood basalts (eruptions where lava covers a very large area) Erupted magma contains <45% silica Very rare, has only happened a few times in the past 550 million years Hottest lavas, even more fluid than common mafic lavas What are the four types of lava? What determines which type of lava a sample is? http://www.nytimes.com/video/science/100 000003431211/how-it-happens-volcaniceruptions.html?playlistId=100000002963017 A popular way of classifying volcanoes is by their frequency of eruption. Active Dormant Extinct Erupt frequently ◦ No agreement among scientists about this Volcanoes that are erupting or show signs that it is likely to erupt About 1,500 active volcanoes in the world ◦ About 50 of these erupt each year ◦ An estimated 500 million people live near active volcanoes Kilauea, the famous Hawaiian volcano, has been in continuous eruption for thirty years, and has the longest-observed lava lake. Mount Etna and nearby Stromboli, two Mediterranean volcanoes in almost continuous eruption since antiquity. Volcanoes that have erupted in recorded history, but show no activity now are dormant or inactive. Can become active seemingly out of the blue. Vesuvius is the most infamous dormant volcano. Yellowstone never erupted in recorded history, but we know its recharge period is around 700,000 years. Dormant volcanoes tend to have a worse effect on civilizations because people are surprised when they erupt. Considered to be very unlikely to erupt again because the volcano no longer has a magma supply. The smaller Hawaiian islands are extinct because they are no longer above the hot spot that supplies the fresh magma. Supervolcanoes sit on massive magma supplies that can stay hot for millions of years, so many scientists won’t consider them extinct. Name one example of an active, a dormant, and an extinct volcano. Destroying stuff https://www.youtube.com/watch?v=gzainwT1mr A https://www.youtube.com/watch?v=Fcz3vBdI7Nc &feature=kp https://www.youtube.com/watch?v=Zf4wKY8PJtg Creating energy https://www.youtube.com/watch?v=Q1UaOCe0E CI Ash clouds Earthquakes Hot springs Fumaroles Mud pots Geysers Consists of fragments of pulverized rock, minerals, and volcanic glass created during volcanic eruptions. ◦ Less than 2mm in diameter It can be dispersed thousands of miles away from the volcano. ◦ Causing crops to die, flights to be cancelled, water to be contaminated, etc. What happens on the ground? https://www.youtube.com/watch?v=TK7JAKP 66kY A spot where hot water flows to the surface of the Earth from the ground. The water is heated from coming into contact with the magma below the surface of the Earth. Occur all over the world. https://www.youtube.com/watch?v=HOuiI9N 5miY An opening in the Earth’s crust which emits steam and gases. ◦ Carbon dioxide, sulfur dioxide, hydrogen chloride, and hydrogen sulfide. Superheated water turns to steam as its pressure drops when it emerges from the ground. A hot spring with limited water in the form of a pool of bubbling mud. The acid and microorganisms decompose surrounding rock into clay and mud. https://www.youtube.com/watch?v=a9hUsVq 9q7U A spring characterized by intermittent discharge of water ejected turbulently and accompanied by steam ◦ https://www.youtube.com/watch?v=X4zA_YPCyHs Water in contact with the hot magma boils and pressurizes, eventually shooting out of a vent on the surface. https://www.youtube.com/watch?v=H8lF3f4R vGo https://www.youtube.com/watch?v=CRoNhfL ufDA Geyser Guy ◦ https://www.youtube.com/watch?v=_gyhvqbIaOE Describe the 6 effects of a volcano we went over? Pick one of the effects of a volcano we talked about and explain what possible dangers it poses to people. Pick up a piece of paper and read through the questions. Complete the online activity Hawaii is made from which type of volcano? Begin volcano quiz