Geophysics is the study of Earth and its atmosphere and waters by means of the science of physics. Geophysics is an extremely broad field that combines numerous narrower fields of study. For example, it includes seismology, the study of earthquakes; hydrology, the study of the movement and distribution of water; and meteorology, the study of the atmosphere and weather.
Geophysicists measure Earth’s shape, temperature, gravity, electricity, and magnetism. They attempt to answer questions about the origin and history of Earth. They also study volcanoes, oceans, and the forces and processes in Earth’s interior.
Geophysics has led to a better understanding of earthquakes and other forces that shape Earth. According to the theory of plate tectonics, Earth’s outer shell, called the lithosphere, consists of a number of rigid plates (see Plate tectonics). Geophysicists have found that the majority of earthquakes occur at the edges of these plates. The plates are continually in motion, and an earthquake occurs when two plates suddenly slip past each other. Geophysicists are developing methods of predicting when and where earthquakes will occur (see Earthquake).
Scientists called oceanographers use geophysical techniques to study the ocean and the land beneath it. Geologists use geophysical methods to search for underground deposits of minerals, natural gas, and oil. For example, geologists measure the slight variations in gravity that occur from place to place. By using such measurements, they can locate rock formations where oil is likely to be found.
One of the newest branches of geophysics, planetary exploration, involves the study of other planets, especially Jupiter, Mars, and Venus. Geophysicists compare Earth with other planets to understand Earth and its origin better. A geophysical topic of worldwide concern is the decrease in the ozone layer in the upper atmosphere (see Ozone hole).
