Volcanoes Lesson 3.1 PDF

THIRD QUARTER: EARTH SCIENCE  are Sources of Geothermal Energy VOLCANOES give Information about the Earth Are classified according to their may undergo Eruption Morphology...

THIRD QUARTER: EARTH SCIENCE  are Sources of Geothermal Energy VOLCANOES give Information about the Earth Are classified according to their may undergo Eruption Morphology Activity Types Composition Cinder Cone Active Hawaiian  Water Vapor  Carbon Dioxide  Hydrogen Gas Composite Inactive Strombolian  Hydrogen Chloride  Hydrogen Fluoride Vulcanian  Hydrogen Sulfide Shield Extinct  Sulfur Dioxide Plinian  WHAT IS A Volcano An elevated landform with an opening at the top called crater. This is where the lava and other rock fragments, steam, gases, ash, heat, and other volcanic materials are ejected  the mouth of a volcano, cloud of ash formed during surrounding the vent eruptions a smaller opening wherein volcanic an opening in the Earth’s materials also escape surface through which volcanic materials escape a mass of molten rock an underground ejected during an passage where eruption magma travels a side of through the volcano a large underground pool of liquid rock found beneath the surface of the Earth  Magma HOW IS FORMED  Magma HOW IS FORMED CRUST Magma is a semi-molten rock, which tries to escape upward MANTLE through spaces between plates toward cooler areas on the CORE crust  Magma HOW IS FORMED Subduction is a geological process that takes place at convergent boundaries  HOW Magma One plate moves under another and is IS FORMED Plate movements increase friction and forced to sink due to high gravitational pressure, generating high temperatures potential energy into the mantle causing rocks to melt  HOW Magma IS FORMED Once magma reaches the crust, it is called lava that flows over the surface, building layer upon layer until a volcano is formed Comparison of the three convergence  TYPES of Volcanoes ACCORDING TO MORPHOLOGY  Cinder - Also known as scoria cone - Formed by fluid lava that is ejected because of high pressure that builds up CONE in the magma chamber - Eruptions are short-lived and appear like a wild fountain of fiery lava spewed high in the air CINDER CONE VOLCANOES CINDER CONE VOLCANOES Paricutin (Mexico) Cerro Negro (Nicaragua) - Formed by loose and fluid lava that flows over each other - Usually low and broad - Lava flows and runs down the side of the crater, increasing the size of volcano - The magma contains lower amounts of dissolved gases and silica SHIELD VOLCANOES  SHIELD VOLCANOES Kilauea (Hawaii) Mauna Kea (Hawaii) Mauna Loa (Hawaii) - Also known as stratovolcano - Formed by highly viscous or thick, slow-moving magma - Magma has high levels of dissolved Composite gases and silica - Has steep upper MOST DANGEROUS slopes and relaxed lower slopes, has TYPE OF small crater at its VOLCANOES summit with large reservoir of magma COMPOSITE VOLCANOES COMPOSITE VOLCANOES Mayon Volcano Mount Pinatubo Mount Kilimanjaro (Africa) Mount Vesuvius (Italy) Mount Fujiyama (Japan) OTHER ASSOCIATED Volcano LANDFORMS  OTHER ASSOCIATED LANDFORMS CALDERA COMPLEX - A depression formed at the summit of shield volcanoes - When calderas explode, they collapse over each other, creating new depressions or calderas instead of adding or increasing the size of the volcano  OTHER ASSOCIATED LANDFORMS LAVA DOME - Lava domes are mounds of lava formed after a volcanic eruption - Its magma has high levels of silica and low amounts of dissolved gases - They can form inside the crater of a volcano or along its slopes Mount Amorong (Pangasinan) OTHER ASSOCIATED LANDFORMS SUBMARINE VOLCANOES - These are volcanoes on the ocean floor - Formed through collisions of oceanic plates Didicas (Cagayan) OTHER ASSOCIATED LANDFORMS GLACIAL VOLCANOES These are volcanoes that are overlain by glaciers Alaskan Volcano  TYPES of Volcanoes ACCORDING TO ACTIVITY  Exhibits volcanic activity such as rumbling, crater glow, eruption and earthquakes within the last 10 000 years Dormant Shows no historical record of eruption in the past 10 000 years but has the potential to erupt thus, also referred to as potentially active Has no magma supply and no record of eruption  The Pacific Ring of Fire is a string of volcanoes and site of seismic activity around the edges of the Pacific Ocean Pacific The Ring of Fire affects 4 Ocean continents and 8 tectonic plates Equator 4 continents 8 tectonic plates Asia Philippine Eurasian Oceania Cocos Indo-Australian North America Nazca North American South America Pacific South American The Philippines is an archipelago of more than 7,100 islands and most of them are of volcanic origins Twenty-four of these are active while larger percentage remains dormant as of the record  SIX MOST ACTIVE VOLCANOES PINATUBO TAAL MAYON BULUSAN KANLAON HIBOK-HIBOK  ACTIVE VOLCANOES IN THE PHILIPPINES Cabalian Leyte 1 1820 Isarog Camarines Sur 1 3500 BCE HOW and WHY do Volcanoes Erupt  HOW and WHY do Volcanoes Erupt Magma is buoyant and will rise through the crust to erupt on the surface The manner of eruption depends on the magma’s viscosity which is affected by 2 factors and gas content:  Temperature (inverse)  Silica Content (direct)  HOW and WHY do NOTE: Volcanoes Erupt  High viscosity magma is very thick and pasty. It usually has a large amount of gas content (trapped exsolved gas). It usually erupts violently.  Low Viscosity magma is thin and runny with little gas content (trapped exsolved gas). It usually erupts with thin flows of lava very quietly.  EXPLOSIVE ERUPTIONS Ash fall Pyroclastic flow Pyroclastic surge -Formed with large amounts of gas and highly viscous magma -Erupt tens up to thousands cubic kilometer of magma -Sends ash clouds greater than 25 kilometers into the stratosphere -Have severe environmental and climatic effects  EXPLOSIVE ERUPTIONS Ash fall Pyroclastic flow Pyroclastic surge -Formed with large amounts of gas and highly viscous magma -Erupt tens up to thousands cubic kilometer of Mt. Pinatubo, Philippines magma -Sends ash clouds greater than 25 kilometers into the stratosphere Mt. -Have severe environmental and Merapi, climatic effects Indonesia Mt. Redoubt, Alaska EFFUSIVE ERUPTIONS Formed with small amounts of gas and/or low viscosity magma Characterized by outpourings of lava onto the ground  EFFUSIVE ERUPTIONS Formed with small amounts of gas and/or low viscosity magma Characterized by outpourings of lava onto the ground Molten Rivers in Zaire, Africa Appalachian Mountains Mauna Loa, 1984  TYPES of ERUPTION HAWAIIAN ERUPTION -The least violent type, with highly fluid or runny lava flowing out several vents -Creates shield volcanoes  Strombolian ERUPTION -A violent eruption featuring continuous ejection of magma and gas -It results in the formation of volcanic bombs and cinder cones VULCANIANERUPTION -A thick viscous magma flows around the vent as solid lava and dust are ejected -Characterized by a dense cloud of ash-laden gas exploding from the crater and rising above the peak -They usually commence with Phreatomagmatic eruptions which can be extremely noisy due the rising magma heating water in the ground PLINIAN PLINIANERUPTION -Most violent and explosive type of eruption -Caused by the build-up of viscous magma and dissolved gas -Accompanied by fast-flowing pyroclastic debris and lahars  These are hot bursts of trapped gases that push their way through solid barriers and rapidly into the atmosphere  Released by active and inactive volcanoes Contains: Water vapor, Carbon Dioxide, Hydrogen gas, Hydrogen chloride, Hydrogen Fluoride, Hydrogen Sulfide, Sulfur Dioxide Refers to the molten rocks that move down the slope of volcanic vents The viscosity of magma and steepness of the volcano can influence the rate of lava flow PYROCLASTIC FLOW Refers to the glowing hot material that moves down the slope of an erupting volcano and comes in contact with the surface PYROCLASTIC SURGE These are volcanic materials of gases, ash, rock fragments, and water extruded above the ground Also called mudflow or flow of volcanic debris Primary lahar (hot) – eruption Secondary Lahar (cold) - rainfall  Refers to a mound of lava that grows inside the crater, called a cryptodome. If it grows outside a volcano, it is called an exodome.  Volcanic Ash Lapilli Fragments of rock that are produce when magma or rock is explosively ejected Volcanic Bomb  Series of sea waves caused by the displacement of large volumes of water because of an underwater earthquake or volcanic eruption