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Earthquakes

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Earthquakes

  1. 1. FOCUS
  2. 2. CA- California K-12 Academic Content StandardsSubject : ScienceGrade : Grades Nine Through TwelveArea : Earth SciencesSub-Strand : Dynamic Earth ProcessesConcept 3: Plate tectonics operating over geologic time has changed the patterns of land, sea, andmountains on Earth’s surface. As the basis for understanding this concept:a: Students know features of the ocean floor (magnetic patterns, age, and sea-floor topography) provideevidence of plate tectonics.b: Students know the principal structures that form at the three different kinds of plate boundaries.c: Students know how to explain the properties of rocks based on the physical and chemical conditions inwhich they formed, including plate tectonic processes.d: Students know why and how earthquakes occur and the scales used to measure their intensity andmagnitude.
  3. 3. 1. Compare and contrast plate boundaries: convergent, divergent, and transform2. Learn about the causes and effects of earthquakes and where they occur
  4. 4.  Seismologist- scientist who studies seismic waves
  5. 5.  *Convection Currents move tectonic plates. *Convection Currents in the Earth are caused by the Earth’s hot inner core heating the magma within the mantle.
  6. 6.  The movement of tectonic plates is related to the distribution of heat by convection currents in the mantle.
  7. 7.  *A Fault is a fracture, or break, in Earth’s Lithosphere.  Along parts of the fault, the rocks on either side may slide along slowly and constantly.  Along other parts of the fault, the rocks may stick, or lock together.  The rocks bend as stress is put on them.
  8. 8.  *Stress: Force exerted when an object presses on, pulls on, or pushes against another object.  *As stress increases, the rocks break free. A sudden release of stress in the Lithosphere causes an earthquake
  9. 9.  *An Earthquake is the shaking of the ground caused by a sudden movement of large blocks of rock along a fault. *Most faults are located along tectonic plate boundaries, therefore, most earthquakes occur at those points.  The rocks that move are much smaller than the tectonic plate.
  10. 10.  Tectonic Plates can be thousands of kilometers long.  During even a powerful earthquake the rocks may only move a few meters past each other along a distance of several hundred kilometers. *The strength of an earthquake depends in part on:  *How much stress builds up (potential energy) before the rocks move.  *The distance the rocks move along the fault.
  11. 11.  80% of all earthquakes occur in a belt around the edges of the Pacific Ocean.  In the U.S. the best-known Fault in this belt is the San Andreas Fault in CA.  The Fault forms part of the boundary between the North American Plate and the Pacific Plate.
  12. 12.  The San Andreas, unlike many other Faults, can be seen on the surface of the ground. Earthquakes also occur along Faults within plates. All Earthquakes occur in the Lithosphere where the rocks are cold, hard and brittle. Below the Lithosphere is the hot malleable, and in spots, molten. A few Earthquakes occur far below the normal depth of the Lithosphere because the plates being Subducted are still cold and rigid enough to break.
  13. 13. AQ  All Earthquakes occur in the Lithosphere where the rocks are cold, hard and brittle A Below the Lithosphere is the hot malleable, and in spots, molten.
  14. 14. Can you identify which of the plates are only made of oceanic crust?
  15. 15.  Use usgs.gov to find earthquakes in real-time to map the tectonic plates.
  16. 16.  Write three questions from this section, look in the book or on the Internet for the answers.  Pg 543-551

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