A seismic survey is conducted to generate an accurate picture of the Earth's subsurface and geologic structure. This is achieved by using seismic waves, which are artificially generated vibrations that travel through the ground. By analyzing the way these waves propagate and reflect off different layers of rock and sediment, geologists can determine the composition, depth, and structure of the subsurface. This information is valuable in various industries, such as oil and gas exploration, mining, and civil engineering, as it helps in locating potential resources, assessing geological hazards, and planning infrastructure projects.