Natural Disasters Energy Sources and Earth s Structure Earths Energy Sources Earth s Internal Structure Introduction to Plate Tectonics Natural Processes or Natural Disasters The earth is a dynamic planet with complex internal and external flows of energy that produce natural processes that are supposed to happen and have been for billions of years Natural disasters occur when the earth s natural processes concentrate energy and then release it causing property damage and or loss of life Energy Sources for Natural Disaster Solar Energy Earth s Internal Heat Origin of the Solar System B Rotating mass contracts and flattens with most of the mass in the center A Rotating cloud of dust and gas gathers due to gravitational forces C The center contracts into a ball of hot gas and dust which ignites to form the sun D Accretion results in planet formation whereby the gases outside of the sun condense into solid materials The Solar System Solar Energy The Sun is the Power House for the entire Solar System It is a fairly typical star that is not burning but is fusing together Hydrogen to form Helium In so doing it releases energy in vast quantities Fusion of Hydrogen into Helium The Hydrologic Cycle Uneven Distribution of Solar Energy Causes Severe Weather Earth s Internal Heat Three Sources of the Earth s Internal Energy Heat Gravitational collapse Impact Energy Radioactive decay End Result Early Earth is hot hot hot Density Differentiation of the Earth Produces Earth s Internal Structure Crust Mantle Outer core Inner core Refer to pages 17 21 Earth Structure The earth today is the product of over 4 5 billion years of differentiation into layers of varying density The 8 most abundant elements in the earth are oxygen O silicon Si iron Fe magnesium Mg sodium Na calcium Ca aluminum Al and potassium K Earth Structure Density Stratified Layers Earth s Core The earth s core is composed of two parts the inner core and the outer core The inner core is SOLID iron Fe and nickel Ni and the outer core is LIQUID Fe and Ni Refer to pages 17 21 Earth Structure Density Stratified Layers Mantle The mantle extends from roughly 502900km below the earth s surface and is primarily composed of Fe Mg rich silicates minerals Refer to pages 17 21 Earth Structure Density Stratified Layers Crust Is composed of two types Oceanic Crust is 7 10 km thick primarily made of Fe and Mg rich silicate minerals MAFIC low Si and O high Fe and Mg Continental Crust is 2070km thick primarily made of Si and O rich minerals FELSIC high Si and O low Fe and Mg Refer to pages 17 21 Earth Structure Density Stratified Layers Density mass volume In General density can be changed by changing either the pressure or temperature Crust vs Mantle The mantle contains MORE Fe and Mg than the oceanic crust and the oceanic crust contains MORE Fe and Mg than the continental crust Because Fe and Mg are DENSER elements the mantle is denser than the oceanic crust and the oceanic crust is denser than the continental crust Earth Structure Layers of Different Strengths The crust and the upper part of the mantle is called the LITHOSPHERE and it is RIGID BRITTLE and behaves ELASTICALLY The part of the mantle directly below the lithosphere is termed the ASTHENOSPHERE which behaves like a PLASTIC a solid that flows Refer to pages 17 21 Plate Tectonic Theory 12 large plates e g Pacific Plate 12 small plates e g Arabian Plate Refer to pages 15 21 Mantle Convection Drives Plate Motion Heat Sources Original heat from formation of the Earth Radioactive decay of U Th and K in the core and mantle Plate Velocity Up to 17 cm yr Types of Plate Boundaries Refer to pages 20 21 Moving plates cause EQ s and volcanoes Refer to pages 20 21 Moving plates cause EQ s and volcanoes Refer to pages 20 21
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