Transcript Earthquakes
Earth’s Crust in Motion • When the Earth’s plates are in motion, earthquakes may occur. • Tier Word • Motion-movement . STRESS • The movement causes stress in the crust. • There are 3 types of stress in the crust • Stress -pressure Musical sliders Tensional Stress (gum) Compressional Stress What happens during an earthquake? • The stress builds and then releases. This is the energy in an earthquake. • An earthquake is the shaking and trembling that is caused by the movement of rock beneath Earth’s surface. Faults • Earthquakes are caused by stress at fault lines. • A fault line is found at the boundaries of two different lithospheric plates. • (it’s the faults fault! ) • haaaaaaaaaaaa Strike slip fault • Caused by shearing • Rocks slip past each other • San Andreas Fault • Normal faults -the land is pulling apart or stretching. • The tension in the crust increases until the rocks fracture. • One block of land slips downward • Fracture-break Reverse Forms by compression hanging wall slides up and over footwall Formed Appalachian Mountains (Thrust) Fault • http://www.iris.edu/gifs/animations/faults.ht m • http://science.howstuffworks.com/nature/n atural-disasters/earthquake3.htm Safety Tips • • • • • • Have an earthquake readiness plan. make your home sturdier, such as bolting bookcases to wall studs, installing trong latches on cupboards, and strapping the water heater to wall Locate a place in each room of the house that you can go to in case of an earthquake. It should be a spot where nothing is likely to fall on you. Keep a supply of canned food, an up-to-date first aid kit, 3 gallons (11.4 liters) of water per person, dust masks and goggles, and a working batteryoperated radio and flashlights. Know how to turn off your gas and water mains. . Mountain Building • Takes millions of years • Caused by compression/converging forces • Formed by folding –bends in rock that form when compression shortens and thickens part of Earth’s crust Mountain Building Cont. • Syncline • Anti-cline • Plateau dip = peak rock bends into an arch =large area of flat land elevated high above sea level Colorado Plateau Folding upward fold Syncline Syncline folded arched rock Anti-Cline-fold Tier words to Know for the Test and Beyond • • Compress -squeeze Geologic event (earthquakes, volcanoes) • • • • • • • • • Interior-inside Motion -movement Anything that starts with the prefix geo-earth Volcanologist- studies volcanoes Seismologist- studies earthquakes Diverge -separate Converge- come together Transform- slip past Stress –pressure/tension Students Stop Here Teacher notes Questions to Think About Essential Questions: • Can we predict earthquakes? Can we predict when volcanoes will erupt? • What do earthquakes and volcanoes tell us about what is happening inside the earth and on the surface? • Do you have to worry about a volcanic eruption or • earthquake where you live? Why or why not? What students need to know for the long run – Unit Enduring Understandings: – Studying historical earthquakes and volcanic eruptions improves our understanding of earth's processes. – Although it is known where earthquakes and volcanic eruptions are likely to happen, there is currently no reliable way to predict precisely when an event will occur. – Volcanoes and earthquakes indicate the high temperatures and pressures that exist in earth's interior. – Volcanism(volcanic activity) and seismic(earthquake) activity vary across the globe Common misunderstandings • • • • • • • • • What do students typically misunderstand? Earthquakes don’t only occur when whole plates slide past each other. Earthquakes don’t create a gap or hole in the earth's surface. Earthquakes don’t occur at one depth. Lava that erupts out of a volcano does not comes from earth's core. Earthquakes don’t cause volcanic eruptions. Plate boundaries are not the same as faults. Lava does not come out of all volcanic eruptions