spheroidal vibration

seismology

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July 14, 2026

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Spheroidal vibrations, also known as S modes, are a type of seismic wave that can cause the entire Earth to oscillate. These vibrations have components of motion both along the radius and along the tangent of the sphere. They are generated by the energy release from earthquakes and can continue for many hours or even days.1

Modern digital seismographs can record these long-period oscillations, providing valuable information about the Earth's interior structure. The periods of these vibrations can range from tenths of seconds to many hours. By analyzing the frequencies and attenuation (damping) of these spheroidal vibrations, scientists can create and refine models of the Earth's internal properties. This is a key method in seismology for understanding our planet's structure.12

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earthquake
Long-period oscillations of the globe
…type, called S modes, or spheroidal vibrations, the motions of the elements of the sphere have components along the radius as well as along the tangent. In the second type, which are designated as T modes, or torsional vibrations, there is shear but no radial displacements. The nomenclature is _nS_l…
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…type, called S modes, or spheroidal vibrations, the motions of the elements of the sphere have components along the radius as well as along the tangent. In the second type, which are designated as T modes, or torsional vibrations, there is shear but no radial displacements. The nomenclature is _nS_l…
Read More