Fracture Zone

A fracture zone is a long, linear scar on the seafloor that extends beyond the active transform fault offsetting a mid-ocean ridge. It marks the trace where crust of two different ages, and therefore two different depths, sits side by side, so it appears as a ridge-and-trough escarpment that can run thousands of kilometers across an ocean basin. Unlike the transform between two ridge crests, the fracture zone is seismically quiet because both walls move in the same direction. Major Pacific examples, the Mendocino, Murray, and Clarion zones, were mapped in the 1950s and helped reveal the offset geometry of seafloor spreading.