Transform boundaries are typically associated with which seismic pattern?

• A. Frequent deep earthquakes at subduction zones
• B. Frequent shallow earthquakes along strike-slip faults
• C. No earthquakes occur at transform boundaries
• D. Subduction megathrusts occur

Answer: (B)

Transform boundaries involve lateral sliding of tectonic plates past one another, producing shear stress that is released mainly as earthquakes along strike-slip faults. The rupture tends to occur near the surface in the crust, so these events are typically shallow and can be quite frequent along these faults, such as the San Andreas Fault. Deep earthquakes are characteristic of subduction zones where one plate dives beneath another, and megathrust earthquakes occur there, not at transform boundaries. The idea that no earthquakes occur at transform boundaries is incorrect because these boundaries are highly seismically active. So the seismic pattern most associated with transform boundaries is frequent shallow earthquakes along strike-slip faults.