Power point in Earthquake Grade 8 Science.pptx

Power point in Earthquake Grade 8 Science

1. Earthquake Earthquake Tsunamis Seismic waves

2. Earthquake the shaking and trembling of Earth that results from the sudden movement of part of Earths crust. most common cause is faulting. Earthquake Tsunamis Seismic waves

3. Earthquake during faulting, energy is released as the rocks break and move . As they move, they cause nearby rocks to move also. most of it occur along the edge of the oceanic and continental plate. Earthquake Tsunamis Seismic waves

4. Earthquake Along faults: normal, reverse, thrust, strike-slip. can occur on the ocean floor. Earthquake Tsunamis Seismic waves

5. Tsunami giant ocean waves. can travel at speeds of 700 to 800 km/h. can be as high as 10 to 20 meters as they approach the coast. one of the world’s worst natural disasters that can hit a country. EARTHQUAKE Tsunamis Seismic waves

6. Earthquake FOCUS OR HYPOCENTER - the point or region where an earthquake ruptures and the rock break. - underground point of origin of an earthquake. EPICENTER - the point on Earth’s surface directly above the focus. Earthquake Tsunamis Seismic waves

7. focus epicenter

8. Seismic waves earthquake waves waves of energy caused by the sudden breaking of rock within Earth or an explosion. energy that travels through Earth and is recorded in seismographs. Earthquake Tsunamis Seismic waves

9. Seismic waves can be distinguish through the properties speed, direction and where they do not propagate. 3 main types: - Primary waves - Secondary waves - Surface waves Earthquake Tsunamis Seismic waves

10. Primary waves Fastest and the first to arrive at a seismic station. can move through solid rock and fluids . compressional or push-pull waves. propagate parallel to the direction in which the wave is moving. Earthquake Tsunamis Seismic waves

11. Secondary wave second to arrive. slower than P-wave. can only move through solid rock they are not always recorded at all locations during an earthquake Earthquake Tsunamis Seismic waves

12. Secondary wave moves rock particles up and down, or side-to-side perpendicular to the direction the wave. Earthquake Tsunamis Seismic waves

13. Surface waves interaction of the P and S waves with Earth’s surface and shallow structure. Slowest travel from the focus directly upward to the epicenter. Earthquake Tsunamis Seismic waves

14. Surface waves Complex motion: up and down, side-to-side bend and twist Earth’s surface (most destructive) Earthquake Tsunamis Seismic waves

15. Seismograph an instrument that detects and measures seismic waves. Seismograph Magnitude Intensity

16. Seismometer electrical version of seismograph. Seismograph Magnitude Intensity

17. Seismogram seismograph’s record of the waves (paper or digital) the higher the wavy lines, the stronger the earthquake. Seismograph Magnitude Intensity

18. Seismogram Seismograph Magnitude Intensity

19. Magnitude how much energy is released during an earthquake. determined from seismic records. Richter scale Seismograph Magnitude Intensity

20. Richter scale Seismograph Magnitude Intensity developed in 1935 by Charles Richter. determined by measuring the largest amplitude (wave height) recorded on the seismogram. measures how much energy an earthquake releases by assigning the earthquake a number from 1 to 10.

21. Richter scale Seismograph Magnitude Intensity each number represents an earthquake ten times stronger than an earthquake represented by the preceding number. any number above 6 indicates a very destructive earthquake.

22. Earthquake Magnitude and its Effect Richter Magnitudes Effects Near epicenter 2.0 and below Generally not felt, but recorde 2.0-2.9 Potentially perceptible 3.0-3.9 Felt by some 4.0-4.9 Felt by most 5.0-5.9 Damaging shocks 6.0-6.9 Destructive in populous regions 7.0-7.9 Major earthquakes; inflict serious damage 8.0 and above Great earthquakes; destroys communities near epicenter

23. Richter magnitude Seismograph Magnitude Intensity can be expressed in two ways: 1) wave amplitude increases ten fold (10X) . 2) energy released increases thirty fold (30X) .

24. Intensity based on effects of earthquakes (structures and people) depends on: distance to quake, population density, nature of surface materials, type of building, observer Modified Mercalli Intensity Scale Seismograph Magnitude Intensity

25. Modified Mercalli Intensity Scale invented by Giuseppe Mercalli  in 1902 measures the earthquake’s effects on a scale of I- Xll (in Roman Numerals). determined by scientists surveying the damage and then rating it on the scale Seismograph Magnitude Intensity

26. Modified Mercalli (MM) Intensity Scale Intensity Description MM I Not felt MM II Felt by people at rest on upper floors of buildings MM III Felt indoors, like a small truck passing; hanging objects swing slightly MM IV Felt indoors by many; like a heavy truck passing; hanging objects swing; windows rattle MM V Felt outdoors; sleepers awakened; small objects and pictures move MM VI Felt by all; crockery breaks; furniture moves; weak plaster cracks

27. Intensity Description MM VII Everybody jruns outdoors; difficult to stand; notice by car drivers; furniture breaks; weak chimneys break at roof line; plaster, loose bricks, and tiles fall MM VIII Damage is slight but may be great in poorly built structures. Driving is difficult; ordinary structure is damaged; chimneys and towers fall MM IX General panic; poor structures destroyed; ordinary masonry and foundations damaged; landslides; ground badly cracked MM X Most masonry structures destroyed; some well-built wooden structures and bridges destroyed; dams and embankments damaged; large landslides; ground badly cracked MM XI Few buildings left standing MM XII Damage nearly total; objects thrown upward into air

28. Isoseismals from the 1906 San Francisco Earthquake