Ground motion refers to the movement of the Earth's surface caused by seismic waves during an earthquake. This motion can vary in intensity and duration, affecting buildings, roads, and other structures. Ground motion is measured using instruments called seismometers, which record the vibrations and help scientists understand the earthquake's impact. The characteristics of ground motion include its amplitude, frequency, and duration. These factors influence how much shaking is felt and how much damage occurs. Engineers use this information to design structures that can withstand ground motion, ensuring safety during seismic events like those caused by tectonic plate movements or volcanic activity.