seismicwaves-ppt presentation in science 10
- 1. Unit 1 Module 2 THE EARTH’s INTERIOR
- 2. • In Module 1, you have learned about the different processes and landforms along plate boundaries that slowly shaped the Earth’s surface. • In Module 2, you will learn the connection between these processes with the internal structure and mechanisms of our planet.
- 3. What to expect: • This module will help you visualize and understand the composition and structure of the Earth’s interior.
- 4. Studying the Earth’s Interior Scientists tried to explore and study the interior of the Earth. Yet, until today, there are no mechanical probes or actual explorations done to totally discover the deepest region of the Earth.
- 5. The Earth is made up of three layers: •the crust, •the mantle, and •the core.
- 6. The study of these layers is mostly done in the Earth’s crust since mechanical probes are impossible due to the tremendous heat and very high pressure underneath the Earth’s surface.
- 8. In Grade 8, it was mentioned that seismic waves from earthquakes are used to analyze the composition and internal structure of the Earth.
- 9. What are seismic waves?
- 11. What are seismic waves?
- 12. Earthquake- is a vibration of the Earth produced by the rapid release of energy most often because of the slippage along a fault in the Earth’s crust. This energy radiates in all directions from the focus in the form of waves called seismic waves, which are recorded in seismographs.
- 13. Seismic waves • It is a mechanical vibrations that occur inside the Earth which caused by the breakage of rocks.
- 14. • A seismograph, or seismometer, is an instrument used to detect and record earthquakes.
- 15. Two main types of seismic waves •Body waves – Primary waves (P waves) –Secondary waves (S waves) •Surface waves – Love Waves –Rayleigh Waves
- 16. Surface waves • Surface Waves - can only travel through the surface of the Earth. They arrive after the main P and S waves and are confined to the outer layers of the Earth. • There are two types of surface waves: –Love waves –Rayleigh waves
- 18. Love Waves • Love wave is named after A.E.H. Love, a British mathematician who worked out the mathematical model for this kind of wave in 1911. • It is faster than Rayleigh wave and it moves the ground in a side-to-side horizontal motion, like that of a snake’s causing the ground to twist. • This is why Love waves cause the most damage to structures during an earthquake.
- 19. Rayleigh wave • It was named after John William Strutt, Lord Rayleigh, who mathematically predicted the existence of this kind of wave in 1885. • A Rayleigh wave rolls along the ground just like a wave rolls across a lake or an ocean. • Since it rolls, it moves the ground either up and down or side-to-side similar to the direction of the wave’s movement. • Most of the shaking felt from an earthquake is due to the Rayleigh wave.
- 20. Unlike surface waves, body waves can travel through the Earth’s inner layers. With this characteristic of the body waves, they are used by scientists to study the Earth’s interior. These waves are of a higher frequency than the surface waves.
- 21. Body Waves • Unlike surface waves, body waves can travel through the Earth’s inner layers. • With this characteristic of the body waves, they are used by scientists to study the Earth’s interior. • These waves are of a higher frequency than the surface waves.
- 22. The two types of body waves are: P-waves (primary waves) S-waves (secondary waves).
- 24. Primary waves (P waves) • The P-waves also called compressional waves, travel by particles vibrating parallel to the direction the wave travel.
- 25. Primary waves properties • Travel faster than S-wave • Longitudinal/compressional • Travel through solids/liquids/gas • Double the speed of s-waves • 1450 m/s in water • 5000 m/s in granite
- 26. Secondary wave (S-wave) • Also known as Shear waves. • The S-waves move as shear or transverse waves, and force the ground to sway from side to side, in rolling motion that shakes the ground back and forth perpendicular to the direction of the waves.
- 27. Secondary wave properties • Travel slower than p-waves • Transverse/shear wave • Can only travel through solids only
- 28. Scientists gained information about the Earth’s internal structure by studying how seismic waves travel through the Earth.
- 30. Seatwork: • Using the given organizer, write the necessary information to complete the concept about seismic waves.
- 32. Answer briefly: • Differentiate surface waves from body waves. • Which type of waves do you think were useful to seismologists in their study of the Earth’s interior? Explain your answer.
- 35. Answers to questions: Differentiate surface waves from body waves. • Surface waves travel only on the Earth’s surface like ripples of water while body waves travel through the Earth’s body (interior). In addition, surface waves arrive last at seismic recording stations compared to the body waves.
- 36. Answers to questions: Which type of wave do you think were useful to seismologists in their study of the Earth’s interior? Explain your answer. • The body waves were used by seismologists because they can pass through the Earth’s interior.