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.
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
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
28. Locating an Earthquake
a. To find the epicenter, analyze the
difference between arrival times of P
& S waves
29. Locating an Earthquake
a. 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 Earthquake
a. 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 Earthquake
a. 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
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
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.
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.
