The Layers of Earth Plate Tectonics Volcanoes and

The Layers of Earth, Plate Tectonics, Volcanoes and Earthquakes

Warm-up Be ready for class, take out your article “Can humans travel to the center of the Earth” and the questions. How do scientists know about Earth’s interior even though they have never seen the inside of the Earth? • Which part of the Earth is broken into several large tectonic plates?

Answer • Scientists know though studying seismic waves, gravity, lava from volcanoes and earth’s magnetism. • The lithosphere is broken into large plates. • show video: https: //youtu. be/IWZky 7 m. Xo. O 0

WARM-UP • Which Earth layer has the greatest density? • What are the layers in order from the crust inward? • What are tectonic plates made up of? • Why is the inner core solid even though it is the hottest layer of the Earth?

Warm-up What is TRUE about the layer directly below Earth’s plates? • A. It is mostly solid rock • B. It is mostly liquid rock • C. It is mostly slightly softened rock.

WARM-UP • Get your “register tape” off of the cabinet from yesterday. Take your handout that goes with it off of the front table or take it out if you kept it. Continue working, you will have about 10 minutes to finish.

Warm-up • Log in to http: //www. discoveryeducation. com/ • USER: wcp+ student ID (don’t use the plus) • PASSWORD: Student ID • Click on assignments, select Plate tectonics and more assignment board. Complete all activities and answer questions and fill out chart on the dances with plates handout.

Answer the following in complete sentences: Which of the following are part of earth’s plates? – Continents but not ocean basins – Ocean basins but not continents – Both ocean basins and continents – Neither ocean basins nor continents Which of the following is TRUE about earth’s plates? – They are separated by oceans. – They are piled on top of one another within the earth. – They fit closely together with each plate touching all the plates that are next to it. – They are surrounded by melted rock and do not touch each other.

• What causes the convection currents to form in the mantle?

Warm-up • Any last minute questions before the vocab. assessment? Please write them down. • If finished create a word wall picture using one of the Earth structure/plate tectonics vocabulary terms or work on extra credit.

Warm-up • Name and define the 3 main types of plate boundaries. • What types of “natural disasters” can occur at these boundaries?

ANSWER • Transform • Convergent • Divergent Earthquakes and volcanoes can occur at these boundaries.

Warm-up • 1 st period: Sign out a computer. Choose whether to work on the RAFT or discovery education board (remember this is the only full class day to work on it (you will have some time on Monday). • Go to my website and read the discovery education instructions under classwork links, land beneath our feet main page (scroll down). • Log in to http: //www. discoveryeducation. com/ • USER: wcp+ student ID (don’t use the plus) • PASSWORD: Student ID

These are the terms on the vocabulary test… • Copy these onto loose leaf paper in your binder so you can study them.

Warm-up Which of the following is TRUE about earth’s plates? – They are separated by oceans. – They are piled on top of one another within the earth. – They fit closely together with each plate touching all the plates that are next to it. – They are surrounded by melted rock and do not touch each other.

Warm-up • Any last minute questions before the vocab. assessment? • When finished complete the drawings from yesterday’s snack tectonics, then create a word wall picture using one of the Earth structure/plate tectonics vocabulary terms (due by Monday next week) or work on late work.

Review day • Be ready for class-IN SEAT, PENCIL, BINDER/NOTEBOOK • Take out your completed study guide and look over your answers and discuss with ONLY your table partner (if you do not have a table partner you may join another group. ONLY discuss material on study guide, you have 3 minutes after the bell.

Test day • Be ready for the test, pencil, no talking, quietly studying OR write down any last minute questions. • After the test: Pick up the Rock cycle reading packet from the front table. Read the article, underline/highlight important definitions and info. , next complete the attached handouts (follow directions)

How do we know what the Earth is made of? • Geophysical surveys: seismic, gravity, magnetics, volcanoes, & electrical conductivity

Earth Layers “Review” • The Earth is divided into four main layers. *Inner Core *Outer Core *Mantle *Crust

The Crust * The Earth’s crust is like the skin of an apple. It is very thin compared to the other three layers. *The crust makes up 1% of the Earth. * The crust of the Earth is broken into many pieces called plates.

• The Mohorovicic Discontinuity, or "Moho", is the boundary between the crust and the mantle. The red line in the drawing at right shows its location. In geology the word "discontinuity" is used for the place at which seismic waves change velocity.

The Mantle • The mantle is the layer below the crust. • The mantle is the largest layer of the Earth. • The mantle is divided into two regions: the upper and lower sections.

Lithosphere – the layer of earth made of the crust and the rigid rock of the upper mantle which is broken into tectonic plates Asthenosphere – the layer in earth’s upper mantle directly under the lithosphere in which rock is soft and weak because it is close to melting.

Outer Core * The core of the Earth is like a ball of very hot metals. * The outer core is liquid. * The outer core is made up of nickel and iron (very dense).

Inner Core * The inner core of the Earth has temperatures and pressures so great the metals are squeezed together and are not able to move. * The inner core is a solid.

Data Table Name of Thickness Layer What Layer is Made Of – Consistency Temperatur e Pressure crust 6 -70 km solid rock, <870 ˚C Low mantle ~2, 900 km hot, but solid material 870 - Medium outer core ~2, 300 km molten iron and nickel 44006100˚C High inner core ~2, 400 km solid iron and nickel 7, 0008, 000 ˚C Super Intense mostly granite and basalt 4400˚C

Review 1) What are the four layers of the Earth? 2) The Earth’s crust is very ______? 3) The mantle is the largest layer of the Earth? True or False 4) Is the Outer Core a liquid or a solid?

Answers! 1) Crust, Mantle, Outer Core, Inner Core 2) Thin 3) True 4) Liquid

Plate Tectonics If you look at a map of the world, you may notice that some of the continents could fit together like pieces of a puzzle.

Who is Alfred Wegener? A German scientist who hypothesized theory of continental drift.

What is the Theory of Continental Drift? A hypothesis that all the continents were once joined together in a single land mass called Pangaea and has since drifted apart.

Why wasn’t Alfred Wegner’s theory accepted? -Alfred Wegner had a lot of evidence to support his theory, but. . . He could not explain how the plates moved. -Because he could not explain how the plates moved, scientists did not accept his theory. BUT his theory later developed into theory of plate tectonics…

WHAT IS THEORY OF PLATE TECTONICS? -The Earth’s crust is divided into 12 major plates which are moved in various directions. Pieces of Earth’s lithosphere are in slow, constant motion -Movement is caused by convection currents in the mantle. -Plates move in three types of behavior: This plate motion causes them to collide, pull apart, or scrape against each other. -Tectonic plates are made of continental and oceanic crust

What evidence supports this hypothesis? 1. Geology/Land Features: -He noticed that the mountain ranges on the continents of Africa and South America line up. 2. Fossils: -Fossils-trace of an ancient organisms that has been preserved in rock. -Dinosaur fossils have been found in landmasses separated by oceans. 3. Climate: -Evidence of tropical plants has been found in the Arctic Ocean and glacier evidence in South Africa.

Plate Tectonics • How Plates Move • Diving between two plates • DIVING video showing the mid-Atlantic ridge

Pangaea – a hypothetical supercontinent in which all continents were once attached. It began breaking apart about 200 million years ago Convection – a process by which energy is transferred to cause warmer less dense air or liquid to rise while the dense cooler liquid or air is pushed down.

Tectonic plates – sections of Earth’s upper layer that include both crust and mantle material (lithosphere broken into pieces). Continental drift – a hypothesis that Earth’s continents move on the surface Fault lines – a crack in Earth’s surface

Earth’s Lithospheric Plates

Three Types of Plate Boundaries • Divergent • Convergent • Transform

What is a convergent boundary and where does it occur? -Place where two plates come together, or converge. -A “collision” -Forms mountains and volcanoes -When oceanic crust slips under continental crust: SUBDUCTION -Subduction forms volcanoes

Convergent Boundaries There are three types of convergent plate boundaries 1. Continent-continent collision 2. Continent-oceanic crust collision 3. Ocean-ocean collision

Continent-Continent Collision Make Mountains Himalayas

Continent-Oceanic Crust Collision Also called subduction, forms volcanoes The ring of fire in the Pacific Ocean is formed by subduction zones.

Ocean-Ocean Plate Collision • Forms deep ocean trenches • Mariana Trench in the Pacific is 11 km deep!

What is a divergent boundary and where does it occur? -Place where two plates spread apart; or diverge -Molten material moves up between the plates and forms NEW ocean floor, rift valleys and ocean trenches.

Divergent Boundaries This map shows the age of the oceanic crust. The red coloring shows the youngest ages, whilst the dark blue shows the oldest ages (around 200 million years old). The divergent boundary runs straight through Iceland….

What is a transform boundary and where does it occur? Where two plates slide past each other in opposite directions. Earthquakes occur when two plates slide past each other.

Transform Boundaries San Andreas Fault

• Plate Tectonics in Action Video

Volcanoes A volcano is an opening in the Earth’s crust through which molten rock, rock fragments, and hot gases erupt.

Volcanoes erupt many types of materials: • Magma • Rock fragments • Volcanic gases (mixture of water vapor , carbon dioxide, and ashes) • Pyroclastic flow – mixture of gases and rock fragments that form a dense cloud

Magma and Lava Magma is molten rock BENEATH the Earth’s surface. When magma erupts, it is called lava. Lava is molten rock, or magma that reaches the Earth’s surface through a volcano. Video of a geologist going into an active volcano: https: //app. discoveryeducation. com/learn/videos/4 BDE 23 EC -6 EF 8 -4 C 5 A-B 6 BC-2 AA 0 E 6 DEFAB 7? has. Local. Host=false

Magma Chambers • Magma collects in areas called “magma chambers”. • Volcanic eruptions occur when a chamber is not large enough to hold additional magma that pushes in. • Magma can remain in a chamber until it cools, forming igneous (intrusive) rock, or it can erupt in the form of lava.

Rock Fragments

Volcanic Gases Volcanic gases look like smoke rising from the volcano. They are a mixture of ash and gases (mostly carbon dioxide). Some volcanic gases combine with water in the air to form acids.

Pyroclastic Flows Sometimes volcanic gases can mix with rock fragments forming a pyroclastic flow. This is a dense cloud of superhot gases and rock fragments that races downhill. It can be as hot as 800°C (1500°F) and can travel faster than 160 kilometers per hour (100 mi/h). Pyroclastic flows are the most dangerous type of volcanic eruption.

Formation of Volcanoes: • Volcanoes are common along tectonic plate boundaries where oceanic plates sink beneath other plates. • Volcanoes are also common along tectonic boundaries where plates pull apart, allowing magma to rise from the mantle. • Occasionally, volcanoes are formed over a hot spot far from a plate boundary.

Volcanoes and their effects • Volcanic eruptions can knock down forests and destroy homes by flowing into the homes or by starting fires. • Volcanic eruptions can clog rivers. • Some volcanic gases combine with water in the air to form acids. • Many volcanic gases are dangerous. They can make breathing difficult and damage the lungs of people and animals. • In West Africa, a sudden release of carbon dioxide from a volcano at the bottom of a lake killed 1700 people in 1986.

Lava Flows. Most lava moves too slow to hurt people. However, it can knock down, cover, or burn nearly everything in its path.

Volcanic Ash • The weight of fallen volcanic ash can cause the roofs of buildings to collapse. • Ash makes roads slippery, and it clogs up machinery, including cars and airplanes. • Large amounts of falling ash can suffocate plants, animals, and people.

Mudflows • Mudflows are landslides that occur when loose rocks and soil are mixed with water. • Mudflows also form as ash mixes into rivers flowing from a volcano. • Fast-moving mudflows can bury entire towns tens of kilometers from an eruption.

Pyroclastic flows In 1902, a pyroclastic flow from an eruption in the West Indies completely destroyed the city of Saint Pierre. Almost 30, 000 people were killed within a few minutes.

Landslides Part of a volcano can collapse and start a landslide. The collapse may be caused by an eruption, an earthquake, or even heavy rainfall. A landslide can cause a tsunami if a large amount of material falls into the ocean.

Steam Explosions Steam explosions occur when magma comes into contact with water. The entire island of Krakatau exploded in 1883, causing a tsunami that destroyed hundreds of towns and killed more than 36, 000 people. Steam explosions can be devastating.

Long-Term Effects of Volcanoes: • Volcanoes build as well as destroy. Material erupted from volcanoes can form new land. Over time, lava flows can form new, rich soil. • Repeated volcanic eruptions can build a magnificent landscape of mountains and valleys. • People live in a volcanic area for its natural beauty or there might be a flourishing tourist industry such as Hawaii.

Formation of Volcanic Islands

Questions!!!!! Answer the following questions - • What are volcanoes? • What is the difference between “magma” and “lava”? • What are the effects of volcanoes on Earth’s land, water, and air?

EARTHQUAKES: WHY? AND HOW?

EARTHQUAKES sudden movement or shaking of the Earth • Caused by plate tectonic stresses • Located at plate boundaries • Resulting in breakage of the Earth’s brittle crust

Earthquakes ▪ The waves travel in all directions. ▪ More than 1, 000 occur a year or one every 30 seconds. ▪ Earthquakes continue until all the energy is used up. ▪ TSUNAMIS- Earthquakes on the ocean floor: causing waves to become greater than 20 meters high.

PLATE TECTONIC STRESSES • • Plate boundaries and faults (= cracks where plate sections are moving in different directions) cause friction as plates move Plates in a fault zone have STICK-SLIP motion – Periods of no movement (stick) and fast movement (slip) – Energy stored as plates stick, – Energy released as plates slip

EARTHQUAKE DAMAGE • Landsides • Building damage • Liquefaction

Damage from Earthquakes ▪ Loss of life ▪ Can cause fires (broken natural-gas lines, electrical power lines, or overturned stoves)

Aftershocks An aftershock is a smaller earthquake that follows a more powerful earthquake in the same area. Sometimes structures weakened by an earthquake collapse during shaking caused by aftershocks.

LIQUEFACTION when a solid (sand soil) becomes saturated with water and acts like a heavy liquid • Results in a loss of soil strength & the ability of the soil to support weight

ANIMATION OF LIQUIFACTION Click

EARTHQUAKE DAMAGE Most caused by SURFACE waves (arrive last)

Seismic Waves Earthquakes produce three types of seismic waves: primary waves, secondary waves, and surface waves. Each type moves through materials differently. In addition, the waves can reflect, or bounce off boundaries between different layers. The waves can also refract, or bend as they pass from one layer into another. Scientists learn about Earth’s layers by studying the paths and speeds of seismic waves traveling through Earth.

EARTHQUAKE WAVES • FOCUS = place deep within the Earth and along the fault where rupture occurs • EPICENTER = geographic point on surface directly above focus • *SEISMIC WAVES produced by the release of energy – move out in circles from the point of rupture (focus) – 2 types: surface & body (travel inside & through earth’s layers) • P waves: back and forth movement of rock; travel thru solid, liquid, gas • S waves: sideways movement of rock; travel thru solids only

Focus and Epicenter All earthquakes start beneath Earth’s surface. The focus of an earthquake is the point underground where rocks first begin to move. Seismic waves travel outward from the earthquake’s focus. The epicenter is the point on Earth’s surface directly above the focus.

EARTHQUAKE WAVES Seismographs record earthquake waves Seismograms show: • Amplitude of seismic waves (how much rock moves or vibrates) • Distance to the epicenter • Earthquake direction

EARTHQUAKE WAVES 3 types of seismic waves show up on seismogram – P waves: shake Earth in same direction as wave; travel thru solid, liquid, gas – S waves: shake Earth sideways to wave direction; travel thru solids only – Surface waves (L waves): circular movement of rock; travel on surface – cause most damage!!

EARTHQUAKE WAVES P waves move through solids & liquids S waves move through solids only!!!

EARTHQUAKE WAVES Body P waves S waves AKA Moves through Movement of rock Primary (1 st to arrive) Secondary (2 nd to arrive - larger) Longitudinal, Compression Transverse, Shear all states of matter (solid, liquid, gas) back and forth movement of rock • push/pull or compression/stretch out • Like slinky down stairs Vibration is same as the direction of travel Can go through solids only Move sideways • • perpendicular to direction of wave travel Like snake

Surface or L Waves ▪ Seismic waves that move along Earth’s surface, not ▪ ▪ through its interior. Make the ground roll up and down or shake from side to side. Slowest moving seismic waves Travel on top of Earth’s surface Cause the largest ground movements and the most damage as they bend and twist the surface

EARTHQUAKE MAGNITUDE measures the size of seismic waves → the energy released by the earthquake Richter scale=measurement of energy released based upon wave amplitude (size of vibration) • <2 to ~10 • Amplitude of wave goes up by 10 (Logarithmic scale, which means each is # is 10 x’s stronger) What you need: • Amplitude (size of vibration = wave height) • Time between arrival of 1 st P and 1 st S waves

HOW TO READ SEISMOGRAMS P & S (body waves) move through earth & arrive first • P & S waves used to calculate magnitude of earthquake • Amplitude = height of wave (how much the rock moves; size of vibration)

Occurrence of Earthquakes ▪ About 80 percent of all earthquakes occur in a belt around the edges of the Pacific Ocean. ▪ In the United States, the best-known fault in this belt is the San Andreas Fault in California.

San Andreas Fault – This is a Transform Boundary that runs from the Gulf of California through the San Francisco area.

Kinds of Faults The three main types of faults are 1) Normal faults, 2) Reverse faults, and 3) Strike-slip faults.

Normal Faults Here the block of rock above the fault plane slides down relative to the other block. Stress that pulls rocks apart causes normal faults. Example - Great Rift Valley of Africa (all divergent boundaries).

Reverse Faults Here the block of rock above the fault plane moves up relative to the other block. Stress that presses rocks together causes reverse faults. These faults can occur near collision-zone boundaries between plates. Example - Himalayan Mountains have many earthquakes along reverse faults (convergent boundaries).

Strike-Slip Faults Here blocks of rock move sideways on either side of the fault plane. Stress that pushes blocks of rock horizontally causes earthquakes along strikeslip faults. These faults can occur where plates scrape past each other. The San Andreas Fault is a strikeslip fault (transform boundary).

Tsunamis A special type of wave that can make water rise more than the height of a 20 story building. This wave, known as a tsunami, is a water wave triggered by an earthquake, volcanic eruption, or landslide. Tsunamis are sometimes called tidal waves.

Essential questions review All students must be able to answer the following questions. ● What are the different layers of Earth? ● Why are Earth’s layers arranged in this order? ● How does the inside of Earth affect the outer layer of Earth (crust)? ● How and why is Earth constantly changing? (In your answer include how crustal plates and ocean basins are formed, move, and interact using earthquakes, heat flow, and volcanoes to reflect forces within the Earth).