If stress is applied quickly to a rock, how is it likely to behave?

When stress is applied quickly to a rock, it is likely to behave in a brittle manner. This behavior is primarily due to the fact that fast loading rates do not allow sufficient time for the rock material to deform plastically. Brittle deformation occurs when the applied stress exceeds the rock's strength, leading to fractures or breaks rather than a gradual change in shape.

In contrast, ductile behavior typically occurs under conditions of slow stress application where the material can flow and deform without breaking. Elastic behavior refers to the ability of a material to return to its original shape after the stress has been removed, which is generally associated with lower rates of applied stress. Fluid-like behavior is not characteristic of solid rocks under stress; instead, it applies to materials that can flow, such as liquids or highly plastic solids.

Given the context of rapid stress application, the behavior observed in rocks aligns best with the concept of brittleness, where the material fails suddenly and without significant prior deformation. Understanding these behaviors is essential in geology and materials science, particularly in contexts like faulting and earthquakes, where sudden stress changes occur.