Step 1: Understanding pitch and net slip.
The pitch of the slickenside lineation is the angle between the horizontal line and the lineation on the fault surface. In this case, the pitch is 30°, and the horizontal slip is 1.25 m. The net slip on the fault can be calculated using trigonometry.
Step 2: Calculating the net slip.
The formula for the net slip is given by:
\[
\text{Net slip} = \frac{\text{Horizontal slip}}{\cos(\text{Pitch})}
\]
Substituting the values:
\[
\text{Net slip} = \frac{1.25}{\cos(30^\circ)} = \frac{1.25}{0.866} = 1.44 \, \text{m}
\]
Step 3: Conclusion.
Therefore, the net slip on the fault is 1.44 m.