Which phenomenon occurs when a building period coincides with the earthquake period?

Resonance is a phenomenon that occurs when an external force or vibration frequency matches the natural frequency of a structure, such as a building. This synchronization can result in amplified oscillations, causing significant stress and potential structural failure. In the context of earthquakes, when the building's natural frequency aligns with the frequency of seismic waves generated by an earthquake, the building can experience intense shaking that may exceed its design limits.

The other options, while related to seismic events, do not specifically address the condition described in the question. Vibration refers to the general movement or oscillation of an object, and while buildings do vibrate during an earthquake, it does not specifically denote the critical condition where the periods coincide. Subduction is a geological process describing the movement of one tectonic plate beneath another, which leads to the generation of earthquakes but is not directly related to the structural response of buildings. Amplification can occur in various contexts, such as when waves propagate through different materials, but the term resonance specifically encapsulates the synchronization of periods that leads to severe vibrations in structures during an earthquake.