Step 1: Understanding the geometry.
The net slip vector (20 m) has a rake of 30° on the fault plane.
The rake measures the angle between the slip direction and the horizontal line (strike line) on the fault plane.
Step 2: Components of motion.
The horizontal (strike-slip) component \( = 20 \cos(30°) = 17.32 \, \text{m} \).
The vertical (dip-slip) component \( = 20 \sin(30°) = 10 \, \text{m} \).
Step 3: Interpretation.
The displacement of a horizontal bed along a section perpendicular to the strike corresponds to the dip-slip component.
Step 4: Conclusion.
Hence, displacement = 10 m.