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EARTH’S INTERIOR

EARTH’S INTERIOR. EARTH’S DYNAMIC SURFACE. CHARACTERIZED BY CONTINUOUS CHANGE EARTHQUAKES SEEM TO HAPPEN IN SPECIFIC LOCATIONS WHAT CAUSES THIS CONSTANTLY CHANGING SURFACE? . TECTONIC PLATES. EARTHQUAKES HAPPEN AT TECTONIC PLATE BOUNDARIES.

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EARTH’S INTERIOR

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  1. EARTH’S INTERIOR

  2. EARTH’S DYNAMIC SURFACE • CHARACTERIZED BY CONTINUOUS CHANGE • EARTHQUAKES SEEM TO HAPPEN IN SPECIFIC LOCATIONS • WHAT CAUSES THIS CONSTANTLY CHANGING SURFACE?

  3. TECTONIC PLATES EARTHQUAKES HAPPEN AT TECTONIC PLATE BOUNDARIES

  4. CONVECTION CURRENTS IN THE ASTHENOSPHERE CAUSE THE PLATES TO MOVE IN DIFFERENT DIRECTIONS – LOOK AT ARROWS DIVERGING CONVERGING

  5. EARTHQUAKES AND FAULTS • An earthquake is caused by the sudden release of energy stored in rocks along a fault • Fault is a crack in a mass of rock along which there has been movement of rock layers on either side of the crack • Focus – where EQ starts below surface • Epicenter – location directly above on land or water

  6. NORMAL FAULT REVERSE FAULT TRANSFORM FAULT

  7. TRANSFORM FAULTSAN ANDREAS FAULT FREQUENT EARTHQUAKES

  8. SAN ANDREAS FAULT NORTH PACIFIC PLATE WEST SIDE MOVES NORTH NORTH AMERICAN PLATE EAST SIDE MOVES SOUTH EAST WEST SOUTH

  9. SEISMIC WAVES • When earthquakes occur, waves of energy SEISMIC WAVES travel outward from the earthquake focus • 3 types of seismic waves are produced AT THE SAME TIME but each behaves differently within earth.

  10. P WAVES • Primary waves or compression waves vibrate parallel to the direction of movement. (slinky) • Travel faster than any other wave (6-8 km./s) • Travel through solids, liquids, and gases

  11. S WAVE • Shear wave or secondary waves vibrate back and forth perpendicular to the direction the wave is moving • Slower than P waves (4-5 kms./s) • TRAVEL THROUGH SOLIDS ONLY

  12. SURFACE OR LONG WAVES • Vibrations travel along earth’s surface in a circular motion at relatively slow speeds (2 kms/s) like waves in a pond Do more damage because they produce more ground movement

  13. SEISMOGRAPH SEISMOGRAM

  14. VELOCITY OF SEISMIC WAVES • Velocity depends on the material they are passing through • Increase density and pressure – greater the velocity • Waves are refracted or bent as waves pass through material with different densities

  15. EARTHQUAKESHADOW ZONES • At an angle of 103° (distance 11,000 kms) from the epicenter both P and S waves disappear • P waves can again be detected at l42° (16,000 kms.) NO S WAVES EVER APPEAR AGAIN • THIS BAND OF 39° IN WHICH NO WAVE ARE OBSERVED IS CALLED THE EARTHQUAKE’S SHADOW ZONE

  16. EARTHQUAKE SHADOW ZONES P WAVES DISAPPEAR FROM 105º -140º S WAVES DISAPPEAR FROM 105º NEVER TO APPEAR AGAIN

  17. ANALYSIS OF SEISMIC WAVES HAVE RESULTED IN THE INFERENCE ABOUT EARTH’S INTERIOR S WAVES CANNOT PASS THROUGH THE LIQUID OUTER CORE

  18. LOCATING THE EPICENTER OF AN EARTHQUAKE • The difference in travel time between P and S waves can be used to determine the DISTANCE from a station to the epicenter • The farther a station is from the epicenter, the GREATER the time interval between the arrival of P and S waves • TO DETERMINE THE EXACT LOCATION OF AN EPICENTER, ITS DISTANCE FROM 3 STATIONS MUST BE DETERMINED AND 3 CIRCLES DRAWN

  19. P WAVES TRAVEL FASTER THAN S WAVES AS DISTANCE FROM EPICENTER INCREASES -THE GREATER THE TIME INTERVAL BETWEEN P AND S WAVES

  20. LOCATING EARTHQUAKE EPICENTER MUST HAVE DISTANCE FROM 3 SEISMOGRAPH STATIONS TO DETERMINE EPICENTER

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