How do strike-slip earthquakes differ from dip-slip earthquakes in terms of ground shaking distribution and fault geometry?

• A. Dip-slip involves vertical motion on dipping faults.
• B. Strike-slip earthquakes produce horizontal motion on vertical or steep faults, with strong lateral shaking along the fault.
• C. Dip-slip events produce horizontal motion.
• D. Shaking distribution is identical for both types.

Answer: (B)

The main idea is that the direction of slip and the orientation of the fault determine how the ground shakes. Strike-slip earthquakes move mainly in a horizontal direction along the fault, which is typically vertical or steep. Because the rupture slides past each other side by side, the strongest ground movement is horizontal and concentrated along the length of the fault, producing prominent lateral shaking that can be felt over long distances along the fault trace.

In contrast, dip-slip earthquakes involve vertical movement as the blocks slide up or down along a dipping fault. The fault plane tilts, so the dominant motion has a vertical component, and the shaking is more up-and-down relative to the fault rather than primarily sideways along it. This is why strike-slip descriptions emphasize horizontal motion on vertical or steep faults with strong lateral shaking along the fault, making it the best fit for how ground shaking distributes and how the fault is oriented.