Gravity anomalies refer to variations in the Earth's gravitational field that differ from the expected gravitational force based on a smooth, uniform model of the Earth. These anomalies can be caused by differences in the distribution of mass within the Earth, such as mountains, valleys, or varying densities of rocks. Scientists measure these anomalies to gain insights into geological structures and processes. These measurements are crucial for understanding the Earth's interior and can help in resource exploration, such as locating oil or minerals. Gravity anomalies are also used in geophysics and geodesy to improve models of the Earth's shape and gravitational field.