Which seismic method uses reflections to identify rock boundaries?

Which seismic method uses reflections to identify rock boundaries?

• A. Magnetotellurics
• B. Gravity survey
• C. Seismic refraction
• D. Seismic stratigraphy

Answer: (D)

The key idea is that boundaries between rock units show up where seismic energy reflects off interfaces with a change in acoustic impedance. Seismic stratigraphy specifically uses those reflections to map and interpret stratigraphic boundaries, layering, and depositional features by examining the pattern, continuity, and amplitude of reflectors. In practice, the reflection data are processed into sections that highlight where one rock unit ends and another begins, making it the method that relies on reflections to identify boundaries. Magnetotellurics surveys electrical properties to infer subsurface resistivity and conductivity, which informs composition and fluids but not rock boundaries from reflections. Gravity surveys detect density contrasts through variations in the gravitational field, again not based on reflected seismic energy. Seismic refraction uses refracted waves and their travel times to determine velocity contrasts and deeper layer arrangements, but it relies on refracted energy rather than reflections to identify boundaries.

The key idea is that boundaries between rock units show up where seismic energy reflects off interfaces with a change in acoustic impedance. Seismic stratigraphy specifically uses those reflections to map and interpret stratigraphic boundaries, layering, and depositional features by examining the pattern, continuity, and amplitude of reflectors. In practice, the reflection data are processed into sections that highlight where one rock unit ends and another begins, making it the method that relies on reflections to identify boundaries.

Magnetotellurics surveys electrical properties to infer subsurface resistivity and conductivity, which informs composition and fluids but not rock boundaries from reflections. Gravity surveys detect density contrasts through variations in the gravitational field, again not based on reflected seismic energy. Seismic refraction uses refracted waves and their travel times to determine velocity contrasts and deeper layer arrangements, but it relies on refracted energy rather than reflections to identify boundaries.