fault plane

The abundance of fluids within these tiny holes reduces friction along the fault plane, allowing the two rock blocks on either side to slide past each other more easily and generate small earthquakes.

The grinding of the two sides against each other on the fault plane sends out waves of motion of the rock in every direction.

One of those inspections drew attention to a clear fault plane that cut across the passage.

When that pressure built up, the surface around that had to move — producing sudden earth movement on a fault plane that separates the ancient sea floor and Kilauea volcano.

The fault plane that moved is the boundary between the ancient sea floor and Kilauea.