Seismic WavesNatural Hazard(A lesson for Earth Science).pptx.pptx

Seismic WavesNatural Hazard(A lesson for Earth Science)

1. EARTHQUAKE WAVES

2. What Causes Earthquake? An earthquake occurs because of geologic forces inside the Earth. These inner forces build up slowly and eventually become so strong that may cause underground rocks to break.

3. Seismic Waves A re the waves of energy that travel either along or near the Earth’s surface. This energy that travels through the Earth is recorded by seismographs.

4. Types of Earthquake Waves

5. 1. Body Waves Are seismic waves that travel through the interior of the Earth . These waves are of higher frequency than surface waves. 01 02

6. 2 Types of Body Waves

7. a. Primary Waves (P waves) The fastest kind of seismic waves. C an move through solid rocks and fluids , like water or the liquid layers of the Earth. K nown as compressional or longitudinal waves because of the pushing and pulling they do. V ibrates parallel to the direction and travelling in a push-pull motion. C an travel at a velocity of about 4 to 6 km/s depending on the nature of the material it passes through. 01 02

8. 01 02

9. b. Secondary Waves (S wave) A rrive second after P waves are being detected. S waves are slower than P waves and can only move through solid rocks, not through any liquid medium . Known as transverse or shear waves , which create the shaking of the ground back and forth perpendicular to the direction the waves (up and down) are moving. S waves have a velocity of 3 to 4 km/s . 01

10. 01 02

11. 2. Surface Waves T ravel only through the crust . These are of lower frequency than body waves, and are easily distinguished on a seismograph. Surface waves are almost entirely responsible for the destruction associated with earthquakes. 01 02

12. 2 Types of Surface Waves

13. a. Love Waves Named after Augustus Edward Hough Love . This wave is the fastest surface wave and moves the ground from side-to-side . Love waves produce entirely horizontal motion. It can travel a velocity of 4 km/s and create more shaking. 01 02

14. b. Rayleigh Waves N amed after John William Strutt . It moves the ground side-to-side and up and down in the same direction that the wave is moving. Most of the trembling felt from an earthquake is due to the Rayleigh wave , which can be much larger than the other waves. 01

15. S eismologists use the seismic waves such as the P waves and S waves to determine the distance from the source of an earthquake by getting the direction and the difference in the time of arrival of the waves. 01 02

16. QUIZ

17. Surface wave Love wave 4 to 6 km/s Earthquake waves 4 km/s Earthquake 3 to 4 km/s Primary waves Secondary waves Surface waves 1 . SECONDARY waves, also known as S waves are the slowest waves among the body waves. 2. EARTHQUAKE releases energy that travels through and around the earth in seismic waves. 3 . SURFACE WAVES are of lower frequency than body waves.

18. Surface wave Love wave 4 to 6 km/s Earthquake waves 4 km/s Earthquake 3 to 4 km/s Primary waves Secondary waves Surface waves 4. One type of surface wave is LOVE WAVES which creates more shaking. 5 . Primary waves can travel a velocity of 4 to 6 km/s . 6. 3 to 4 km/s is the velocity of secondary waves.

19. Surface wave Love wave 4 to 6 km/s Earthquake waves 4 km/s Earthquake 3 to 4 km/s Primary waves Secondary waves Surface waves 7. Seismic waves are also known as EARTHQUAKE WAVES . 8. 4 km/s is the velocity of Love waves 9. The waves that travel the fastest among the body waves PRIMARY WAVES . 10. The type of wave that travels only in solid medium is known as SECONADRY WAVES .

20. What are the movements of the following waves? 11. Primary Waves – PUSH AND PULL 12. S econdary waves – UP AND DOWN 13. Love waves – SIDE TO SIDE 14. Rayleigh waves – SIDE TO SIDE & UP AND DOWN

21. 1.Earthquake waves 2.Three types 3.Primary waves 4.Secondary waves 5.Surface waves 6.Earthquake 7.Surface wave 8.Love wave 9.4 to 6 km/s 10.3 to 4 km/s

22. SEISMIC WAVES DEFINITION MAIN TYPES SUB-TYPES SUB-TYPES SUB-TYPES CHARACTERISTICS CHARACTERISTICS CHARACTERISTICS CHARACTERISTICS waves of energy that travel either along or near the Earth’s surface BODY WAVES SURFACE WAVES PRIMARY WAVES SECONDARY WAVES LOVE WAVES RAYLEIGH WAVES PUSH & PULL SOLID ROCKS/ UP & DOWN TRAVEL THROUGH SOLID ROCKS & F LUID SIDE TO SIDE SIDE TO SIDE & UP AND DOWN