Earth s Structure Earth has 4 layers. The inner core, outer core, mantle and crust. How do we know??? Adaptive Curriculum Determining Planet Layers from Seismic Waves
Earth s Structure Scientists use earthquake data and knowledge about earthquake waves to make inferences about Earth s interior. Both P and S waves move though solid portions of Earth s interior. P waves are refracted by, and S waves can not travel through, the liquid outer core. Earthquake epicenter P wave S wave Inner core Outer core Mantle Core-mantle boundary Shadow zone Shadow zone
Earth s Structure The Inner Core How can the inner core be solid if the temperature increases it is surrounded by a liquid outer core?
Why are planets round? Why is it round?
Earth Structure The Outer Core The convection of iron and nickel in Earth s outer core creates Earth s magnetic field. This field shields us from solar radiation and helps birds fly. It also protects our electronic devices.
Earth Structure The Outer Core
Magnetic Field This flow of liquid iron generates electric currents, which in turn produce magnetic fields
Magnetic Field Magnetic reversal.
Jason Earth Structure The Mantle Deep-sea trench Mid-ocean ridge Deep-sea trench Mantle convection This image shows one model of how mantle convection may contribute to plate movement. Convection currents in the mantle (asthenosphere) move the crust (lithosphere) that rests above.
Earth s Structure The Mantle & Crust The Earth is further divided into rigid Lithosphere, which includes the crust and rigid uppermost part of the mantle, and the Asthenosphere which is the portion of the mantle that acts like hot plastic (wet cornstarch). Asthenos = without strength Crust Oceanic crust Lithosphere Continental crust Lithosphere Mantle Asthenosphe Asthenosphere
Earth Structure The Crust Loactions of quakes, and volcanoes
Earth s Lithospheric Motion Continental Drift plate tectonics continental drift mid-ocean ridge BBC - Cont. Drift & Crust Alfred Wegner proposed the hypothesis of continental drift to explain how a single land mass had separated into separate continents, which drifted apart. Later discoveries supported the idea that the continents had been connected, but demonstrated that the continents were not drifting but attached to moving lithospheric, or tectonic, plates.
Earth s Lithospheric Motion Continental Drift Alfred in his younger years
Earth s Lithospheric Motion Alfred Wegner proposed the hypothesis of continental drift to explain how a single land mass had separated into separate continents, which drifted apart. He sited how there were similar rocks and fossils on continents that are now far apart. Breakup Future NatGeo- Continental Drift Video
Plate Boundaries Dividing plates. Midocean ridges, sea floor spreading, rift valleys, and volcanoes. Slide past each other. Earthquakes and strike-slip faults. Most earthquakes and volcanoes are found on plate boundaries CZ - Types of Plate Boundaries
Earth s Lithospheric Motion The Seafloor is Spreading
Earth s Lithospheric Motion The Seafloor is Spreading Once we were able to see, model, and explore rocks under the oceans, we learned that new crust is being created as plates pull apart driven by opposing convection current in the mantle. Youngest rock was nearest the spreading center.
Earth s Lithospheric Motion The Hypothesis of Continental Drift became the Theory of Plate tectonics.
ESB: Plates Bend, Crack, Melt Earth s lithospheric plate motion create stresses on the rocks resulting in folding, faulting, volcanoes and earthquakes.
ESB: Plates Bend, Crack, Melt Folding of rocks occurs when rocks are ductile and experience compressional stress.
Types of Rocks Stress Mountains are made of rocks that have been deformed under stress. Compression, tension, and shear stress are different types of stress. Tension Compression Shear stress Stresses applied to rocks form folds, faults, and joints.
Bend- Converging Plates Can Cause Mountains Appalachian Mountains are folded mountains A fold is a crumpling of rock due to compressional stress.
Bend- Anticline Older Rocks ì
Bend- Syncline A syncline is a fold structure in which the sides of the fold slope together. Its shape is concave upward. It is a fold with younger rocks on the inside
Crack A fault is a break in the lithosphere along which movement has occurred. Normal faults occur where tension pulls the crust apart. Footwall Hanging wall Normal fault
A fault is a break in the lithosphere along which movement has occurred. Normal faults occur where tension pulls the crust apart. Footwall Hanging wall Normal fault
Crack Reverse faults and thrust faults are caused by compression. Hanging wall Footwall Reverse fault
Crack Reverse faults and thrust faults are caused by compression.
Earth s Motion Transform Boundary - Strike Slip Fault Shear Stress
Earth s Motion Strike-Slip Fault Transform boundaries are where plates are sliding past each other. The San Andreas Fault is a perfect example of this type of transform boundary and strike-slip fault. CZ- Diverge NatGeo- san andreas
Earth s Motion Cracking plates can cause mountains.. Horst Graben
Earth s Motion Fact: 10 magnitude 7 earthquakes every year, and 100 magnitude 6 earthquakes every year. That means a magnitude 6 earthquake happens somewhere in the world every 3.65 days
Earth s Structure and Motion Ring of Fire Area of plate boundaries where earthquakes and volcanoes are common.
CHAPTER 9 Volcanoes VOCABULARY volcano CHAPTER HOME 9.1 How and Where Volcanoes Form hot spot Current Volcanic Activity Volcanoes Make Quakes Volcanic activity takes place primarily at subduction boundaries. 1. Water in the subducted rock is released into the asthenosphere. 4. Some of the magma reaches Earth s surface, and volcanoes form on the overriding continental plate. Oceanic lithosphere Continental lithosphere CHAPTER OUTLINE Asthenosphere 2. The water lowers the melting temperatures of materials in the asthenosphere, leading to magma formation. 3. The magma is less dense than its surroundings, so it rises.
CHAPTER 9 Volcanoes VOCABULARY volcano hot spot CHAPTER HOME 9.1 How and Where Volcanoes Form Volcanic activity takes place primarily at subduction boundaries, and divergent boundaries, where the combination of temperature, pressure, and water content are right for the formation of magma. Rift volcanoes - types and form Oceanic crust Lithosphere Oceanic crust Lithosphere CHAPTER OUTLINE Asthenosphere
CHAPTER 9 Volcanoes VOCABULARY volcano hot spot CHAPTER HOME 9.1 How and Where Volcanoes Form Magma and volcanoes also form at hot spots. CZ hot spot Direction of Plate Movement Kauai Oahu Molokai Lanai Maui Hawaii CHAPTER OUTLINE The Hawaiian Islands formed over a hot spot.
CHAPTER 9 Volcanoes VOCABULARY viscosity lava pahoehoe CHAPTER HOME 9.2 Magma and Erupted Materials The amount of silica in magma affects its viscosity. Basaltic magma has the least silica, so it flows easily. aa pillow lava pyroclastic material pyroclastic flow Silica Content Gas Content Viscosity Type of Eruption Melting Temp. Location Basaltic Magma Least (~50%) Least Least viscous Rarely explosive Highest Rifts, oceanic hot spots SECTION OUTLINE
CHAPTER 9 Volcanoes VOCABULARY viscosity lava pahoehoe CHAPTER HOME 9.2 Magma and Erupted Materials Andesitic and rhyolitic magmas have more silica, so they are more resistant to flow. aa pillow lava pyroclastic material Silica Content Gas Content Basaltic Magma Least (~50%) Least Andesitic Magma Intermediate (~60%) Intermediate Rhyolitic Magma Most (~70%) Most pyroclastic flow Viscosity Least viscous Intermediate Most viscous Type of Eruption Rarely explosive Sometimes explosive Usually explosive Melting Temp. Highest Intermediate Lowest Location Rifts, oceanic hot spots Subduction boundaries Continental hot spots SECTION OUTLINE
CHAPTER 9 Volcanoes VOCABULARY viscosity lava pahoehoe aa pillow lava pyroclastic material pyroclastic flow aa pahoehoe CHAPTER HOME 9.2 Magma and Erupted Materials Gases escape easily from basaltic magma, generating relatively quiet eruptions. Hardened basaltic lava flows on land are characterized as pahoehoe or aa; if the lava cools underwater, it is characterized as pillow lava. Gases tend to be trapped in andesitic and rhyolitic magmas, leading to explosive eruptions. Pyroclastic material, or solid fragments, as well as lava are commonly ejected from explosive eruptions. SECTION OUTLINE
Volcanoes Volcanoes form primarily from subduction activity and magma rising at divergent plate boundaries. They are also produced by hot spots, which are mantle plumes of rising magma at the center of a lithospheric plate. Older volcanoes are further from a hot spot due to plate movement. Joshua and Jennifer Mosser, Briar Woods High School
CHAPTER 9 Volcanoes VOCABULARY shield volcano cinder cone composite volcano lahar caldera lava plateau 9.3 Volcanic Landforms CHAPTER HOME A volcano s shape and structure depend on how it erupts and what materials are released. Shield volcanoes are formed by basaltic lava that flows long distances before hardening. Shield Volcano SECTION OUTLINE
CHAPTER 9 Volcanoes VOCABULARY shield volcano cinder cone composite volcano lahar 9.3 Volcanic Landforms CHAPTER HOME Cinder cones are formed when molten lava is thrown into the air from a vent and breaks into drops. These drops harden into cinders that form a steep cone around the vent. caldera lava plateau UStream - Conder Cone SECTION OUTLINE
CHAPTER 9 Volcanoes VOCABULARY shield volcano cinder cone composite volcano 9.3 Volcanic Landforms CHAPTER HOME Composite volcanoes are formed by layers of pyroclastic materials and lava that have erupted in the past. lahar caldera lava plateau Composite Volcano SECTION OUTLINE
CHAPTER 9 Volcanoes VOCABULARY shield volcano cinder cone composite volcano lahar caldera 9.3 Volcanic Landforms CHAPTER HOME Composite volcanoes are formed by layers of pyroclastic materials and lava that have erupted in the past. A caldera is a large crater-shaped basin that forms when the top of a volcano collapses. lava plateau volcanoes - types and form SECTION OUTLINE
CHAPTER 9 Volcanoes CHAPTER HOME 9.4 Extraterrestrial Vulcanism Volcanic activity has occurred in the past on the moon, Venus, and Mars. SECTION OUTLINE
CHAPTER 9 Volcanoes CHAPTER HOME 9.4 Extraterrestrial Vulcanism Jupiter s moon Io is currently volcanically active. SECTION OUTLINE Io, shown with a volcanic plume 140 kilometers high.
Earth s Structure and Motion
Earth s Structure and Motion
Earth s Structure and Motion Movement along these faults creates earthquakes.
Earth s Structure and Motion Earthquakes originate underground. This is called the focus. The point directly above the quake on the surface is the epicenter. The epicenter is where damage may be the greatest. Most earthquakes originate at FAULTS along plate boundaries. The EPICENTER is the point on Earth s surface directly above the focus. Energy is released at the FOCUS and travels away from it in all directions.
Earth s Structure and Motion The first wave is the P (primary) wave. It is a compressional or longitudinal wave. The S(secondary) wave is a transverse wave. The arrival times of each wave indicate the distance from the epicenter of the quake. Compression Wave direction Expansion Compression Wave direction Wave direction Original position Expansion Compression Particle motion Wave direction Wave direction P wave Particle motion S wave
Earth s Structure and Motion A seismograph is the instrument used to determine earthquake magnitude. The pen is suspended to a rotating barrel that is affixed to the bedrock of the plate. The paper or electronic recording is called the seismogram. Bedrock Bedrock
Richter Scale
Earth s Structure and Motion Magnitude is a measure of the amount of energy released during an earthquake, and you've probably heard news reports about earthquake magnitudes measured using the Richter scale. A magnitude 7 earthquake would produce seismogram waves 10 x 10 = 100 times as high and release energy 32 x 32 = 1024 times as great as a magnitude 5 earthquake.
Earth s Structure and Motion The Modified Mercalli Intensity scale measures the effect that an earthquake has on populated areas. This scale is based upon observation and reports of shaking and damage done to structures. What factors could impact the effect an earthquake has on populated areas?
Earth s Structure and Motion Using seismic data
Earth s Structure and Motion Triangulation
Earth s Structure and Motion Where was that quake? Virtual Quake
Earth s Review Great Review Site
Earth s Structure and Motion A Moment In Time
Earth s Structure and Motion Because it exchanges little matter with its surroundings, Earth is an essentially closed system.
Earth s Structure and Motion Because it exchanges little matter with its surroundings, Earth is an essentially closed system.
Earth s Structure and Motion Because it exchanges little matter with its surroundings, Earth is an essentially closed system.
Earth s Structure and Motion Because it exchanges little matter with its surroundings, Earth is an essentially closed system.
Earth as a System Because it exchanges little matter with its surroundings, Earth is an essentially closed system.
Earth as a System Because it exchanges little matter with its surroundings, Earth is an essentially closed system.