Which method uses seismic waves to image underground structures?

• A. Electromagnetic survey
• B. Geochemical testing
• C. Seismic survey
• D. Open pit

Answer: (C)

Seismic surveys use seismic waves to image underground structures. By generating waves at the surface or in boreholes and recording how they travel through different rocks, geophysicists see reflections and refractions at boundaries between materials with different speeds. Measuring the travel times and the way the waves bounce back lets us build a picture of subsurface features such as layer boundaries, faults, and potential ore bodies. This imaging capability is why seismic methods are central to mapping geology before drilling or mining.

Electromagnetic surveys rely on how rocks conduct electricity, not on wave reflections to form images. Geochemical testing analyzes the chemical composition of soils and rocks rather than imaging structures. An open pit is a mining method, not a sensing technique.