Geophysics
Geophysics applies physical principles and measurements to understand Earth’s structure, materials, fields, and dynamic processes.
Seismic wave: An elastic disturbance that travels through Earth or another material, carrying energy through particle motion. Their travel times and paths reveal underground boundaries and material properties.
Seismic tomography: An imaging method that maps variations in seismic-wave speeds inside Earth from recorded travel times. It images mantle and crustal structure from earthquake and controlled-source data.
Elasticity: The property of a material that allows it to deform under stress and recover when the stress is removed. Elastic behavior determines how seismic waves travel through rocks.
Geology: The science of Earth’s materials, history, structure, and surface processes. Geology often interprets exposed rocks directly, while geophysics infers properties from physical measurements.
Inge Lehmann: A Danish seismologist who identified evidence for Earth’s solid inner core in 1936. Her seismic interpretation established a major feature of Earth’s deep structure.
Gravity anomaly: A measured difference between local gravitational acceleration and a chosen reference value. Variations in subsurface density produce gravity signals used to infer buried structures.
Exploration geophysics: The use of physical measurements to locate and characterize subsurface resources and geological structures. It applies geophysical surveys to mineral, groundwater, and energy exploration.
Seismology: The study of earthquakes, seismic waves, and the structure of Earth inferred from them. It is a major branch of geophysics centered on elastic waves.
Remote sensing: The acquisition of information about objects or areas without direct physical contact, commonly using sensors on aircraft or satellites. It chiefly measures signals from above the surface, whereas geophysics often probes underground structure.
Andrija Mohorovičić: A Croatian geophysicist who identified the seismic discontinuity now marking the crust–mantle boundary. His earthquake-wave analysis revealed a sharp boundary inside Earth.