Class Captures: P and S Wave Travel Times

Introduction

• Host: Jasper Sr.
• Topic: Determining P and S wave travel times and using page 11 in reference table
• Tip: Have the reference table available during this session

Axes Explanation

Horizontal Axis (Distance)

• Labeled "epicenter distance"
• Uses scientific notation (e.g., 10^3)
  • 10^3 = 1,000 (i.e., 10 x 10 x 10)
  • Example: 8 x 10^3 = 8,000
• Scale: Each box equals 200 kilometers
  • Calculation: Difference of 1,000 divided by 5 spaces = 200 km per box
  • Example: Red dot marked at 1,200 kilometers

Vertical Axis (Time)

• Scale of time measured in minutes and seconds
• Each box equals 20 seconds
  • Calculation: 60 seconds divided by 3 spaces = 20 seconds per box
  • Example: A point at 3 minutes and 40 seconds

Earthquake Waves

P Waves (Primary Waves)

• Travel faster, arrive first (similar to lightning in a storm)
• Compression waves (like dominoes falling)
  • Travel through liquids and solids

S Waves (Secondary Waves)

• Travel slower, arrive second (similar to thunder in a storm)
• Shear waves (wiggle like a snake or jump rope)
  • Travel only through solids
  • Energy travels at 90 degrees to wave direction
  • Memory tips:
    • Secondary, Slower, Shear, Solids (all start with "S")

Using the Chart

• Example for P waves:
  • 3,000 km requires 5 minutes and 40 seconds
• Example for S waves:
  • 4,000 km requires 12 minutes and 40 seconds
• Tip: Use a highlighter to differentiate P and S wave lines on the chart

Conclusion

• Recap: Use page 11 of the reference table to determine wave travel times
• Stay tuned for more episodes from Class Captures