4.2 recording earthquakes

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Transcript

  • 1. 4.2 Recording Earthquakes Mr. Silva
  • 2. 4.2 Vocabulary
  • 3. 4.2 Vocabulary• Seismograph- – instrument used to detect and record seismic directions
  • 4. 4.2 Vocabulary• Seismograph- – instrument used to detect and record seismic directions• P Waves- – primary wave: the fastest wave generated by an earthquake and the first to be recorded by a seismograph.
  • 5. 4.2 Vocabulary• Seismograph- – instrument used to detect and record seismic directions• P Waves- – primary wave: the fastest wave generated by an earthquake and the first to be recorded by a seismograph.• S Waves- – secondary wave; a wave generated by an earthquake and the second to be record by a seismograph
  • 6. 4.2 Vocabulary• Seismograph- – instrument used to detect and record seismic directions• P Waves- – primary wave: the fastest wave generated by an earthquake and the first to be recorded by a seismograph.• S Waves- – secondary wave; a wave generated by an earthquake and the second to be record by a seismograph• Surface Waves-
  • 7. 4.2 Vocabulary• Seismograph- – instrument used to detect and record seismic directions• P Waves- – primary wave: the fastest wave generated by an earthquake and the first to be recorded by a seismograph.• S Waves- – secondary wave; a wave generated by an earthquake and the second to be record by a seismograph• Surface Waves- – the slowest moving seismic wave generated by an earthquake and the last to be recorded.
  • 8. 4.2 Vocabulary
  • 9. 4.2 Vocabulary• Magnitude-
  • 10. 4.2 Vocabulary• Magnitude- – Is a measure of the energy released by an earthquake and is also described as the amount of ground motion.
  • 11. 4.2 Vocabulary• Magnitude- – Is a measure of the energy released by an earthquake and is also described as the amount of ground motion.• Microquakes-
  • 12. 4.2 Vocabulary• Magnitude- – Is a measure of the energy released by an earthquake and is also described as the amount of ground motion.• Microquakes- – earthquake with a magnitude less than 2.5 on the Richter scale
  • 13. 4.2 Vocabulary• Magnitude- – Is a measure of the energy released by an earthquake and is also described as the amount of ground motion.• Microquakes- – earthquake with a magnitude less than 2.5 on the Richter scale• Mercalli scale-
  • 14. 4.2 Vocabulary• Magnitude- – Is a measure of the energy released by an earthquake and is also described as the amount of ground motion.• Microquakes- – earthquake with a magnitude less than 2.5 on the Richter scale• Mercalli scale- – scale that expresses the intensity of an earthquake with a Roman numeral and a description.
  • 15. 4.2 Vocabulary• Magnitude- – Is a measure of the energy released by an earthquake and is also described as the amount of ground motion.• Microquakes- – earthquake with a magnitude less than 2.5 on the Richter scale• Mercalli scale- – scale that expresses the intensity of an earthquake with a Roman numeral and a description.• Intensity-
  • 16. 4.2 Vocabulary• Magnitude- – Is a measure of the energy released by an earthquake and is also described as the amount of ground motion.• Microquakes- – earthquake with a magnitude less than 2.5 on the Richter scale• Mercalli scale- – scale that expresses the intensity of an earthquake with a Roman numeral and a description.• Intensity- – amount of damage caused by an earthquake.
  • 17. Types of Seismic Waves• Seismic waves can be detected and recorded using a seismograph.• There are 3 types of seismic waves – Primary Waves (P waves) – Secondary Waves (S waves) – Surface Waves: (when P & S waves reach the surface)
  • 18. Primary Waves– Primary Waves (P waves): move fastest and are recorded first • Can travel through solid & liquid • Compression waves- cause the rock particles to move together & apart along the wave direction
  • 19. Secondary Waves– Secondary Waves (S waves): second to be recorded • Travel only through solid material: cannot be detected on the side of the earth opposite the epicenter…Why? Can’t go through the liquid of the earth’s outer core! • Shear waves- cause rock particles to move at right angles to the wave direction
  • 20. Surface Waves
  • 21. Surface Waves• Surface Waves: when P & S waves reach the surface and their energy is converted into a new wave
  • 22. Surface Waves• Surface Waves: when P & S waves reach the surface and their energy is converted into a new wave – Slowest moving & last recorded
  • 23. Surface Waves• Surface Waves: when P & S waves reach the surface and their energy is converted into a new wave – Slowest moving & last recorded
  • 24. Surface Waves• Surface Waves: when P & S waves reach the surface and their energy is converted into a new wave – Slowest moving & last recorded – Why do surface waves do the most damage?
  • 25. Surface Waves• Surface Waves: when P & S waves reach the surface and their energy is converted into a new wave – Slowest moving & last recorded – Why do surface waves do the most damage?
  • 26. Surface Waves• Surface Waves: when P & S waves reach the surface and their energy is converted into a new wave – Slowest moving & last recorded – Why do surface waves do the most damage? – Not as much earth to absorb energy before hitting the surface
  • 27. Locating an Earthquake
  • 28. Locating an Earthquakea. To find the epicenter, analyze the difference between arrival times of P & S waves
  • 29. Locating an Earthquakea. To find the epicenter, analyze the difference between arrival times of P & S waves i. P waves travel 1.7 times faster than S waves
  • 30. Locating an Earthquakea. To find the epicenter, analyze the difference between arrival times of P & S waves i. P waves travel 1.7 times faster than S waves ii. The longer S waves take to come in, the farther the seismograph station is from the epicenter
  • 31. Locating an Earthquakea. To find the epicenter, analyze the difference between arrival times of P & S waves i. P waves travel 1.7 times faster than S waves ii. The longer S waves take to come in, the farther the seismograph station is from the epicenter iii. Plot epicenter distances from 3 stations and the intersection point is the earthquake epicenter
  • 32. Earthquake Measurement
  • 33. Earthquake Measurement– Magnitude a measurement of the energy released by an earthquake & is the amount of “ground motion”
  • 34. Earthquake Measurement– Magnitude a measurement of the energy released by an earthquake & is the amount of “ground motion” i. Major quake = 7 or above
  • 35. Earthquake Measurement– Magnitude a measurement of the energy released by an earthquake & is the amount of “ground motion” i. Major quake = 7 or above ii. Moderate quake = 6 to 7
  • 36. Earthquake Measurement– Magnitude a measurement of the energy released by an earthquake & is the amount of “ground motion” i. Major quake = 7 or above ii. Moderate quake = 6 to 7 iii. Minor quake = 2.5 to 6
  • 37. Earthquake Measurement– Magnitude a measurement of the energy released by an earthquake & is the amount of “ground motion” i. Major quake = 7 or above ii. Moderate quake = 6 to 7 iii. Minor quake = 2.5 to 6– Largest quake ever had a magnitude of 8.9
  • 38. Earthquake Measurement– Magnitude a measurement of the energy released by an earthquake & is the amount of “ground motion” i. Major quake = 7 or above ii. Moderate quake = 6 to 7 iii. Minor quake = 2.5 to 6– Largest quake ever had a magnitude of 8.9– Anything less than a 2.4 is a microquake.
  • 39. Earthquake Measurement– Magnitude a measurement of the energy released by an earthquake & is the amount of “ground motion” i. Major quake = 7 or above ii. Moderate quake = 6 to 7 iii. Minor quake = 2.5 to 6– Largest quake ever had a magnitude of 8.9– Anything less than a 2.4 is a microquake.– Mercalli scale expresses intensity (damage caused) in Roman Numerals I to XII
  • 40. 4.2 Review
  • 41. 4.2 Review• What instrument is used to record seismic waves?
  • 42. 4.2 Review• What instrument is used to record seismic waves? – Seismograph
  • 43. 4.2 Review• What instrument is used to record seismic waves? – Seismograph• Explain the three types of seismic waves…
  • 44. 4.2 Review• What instrument is used to record seismic waves? – Seismograph• Explain the three types of seismic waves… – P (primary) moves the fastest through solids and liquids.
  • 45. 4.2 Review• What instrument is used to record seismic waves? – Seismograph• Explain the three types of seismic waves… – P (primary) moves the fastest through solids and liquids. – S (secondary) travel only through solids
  • 46. 4.2 Review• What instrument is used to record seismic waves? – Seismograph• Explain the three types of seismic waves… – P (primary) moves the fastest through solids and liquids. – S (secondary) travel only through solids – Surface Wave- Slowest wave, moves over the surface causing the surface to rise and fall.
  • 47. Review
  • 48. Review• How do scientists measure the magnitude of an earthquake?
  • 49. Review• How do scientists measure the magnitude of an earthquake? – By analyzing and plotting the differences in arrival times of P waves and S waves at three or more seismograph station locations
  • 50. Review• How do scientists measure the magnitude of an earthquake? – By analyzing and plotting the differences in arrival times of P waves and S waves at three or more seismograph station locations• Why do P waves travel faster through the lithosphere than through the asthenosphere?
  • 51. Review• How do scientists measure the magnitude of an earthquake? – By analyzing and plotting the differences in arrival times of P waves and S waves at three or more seismograph station locations• Why do P waves travel faster through the lithosphere than through the asthenosphere? – Because P waves travel faster through the more rigid rock of the lithosphere than through the somewhat plastic rock in the asthenosphere.