The measurement of vibration, strain, and temperature in a fiber optic cable relies on the interaction between laser light and the glass in an optical fiber. When light travels through a transparent media, the main pulse travels forward, however, a small fraction is backscattered through interaction with the glass particles.
This changes at every point along the cable in accordance with the local environment. Different backscatter processes can be used to extract relevant information. That backscatter signal can be exploited by different technologies to understand the external environment–vibration, strain, temperature, etc. The end data can be used to understand the environment at every point along the fiber and act on the information.
