Summary of the four coupling scenarios in a two-layer elastic medium (Table 1). α2 and β2 are the P- and S-wave velocities of the half-space, respectively. β1 is the first-layer S-wave velocity. Further details and corresponding references can be found in Section 3.
| Velocity relationship . | Seismic-wave types in the half-space . | Pressure field examples . | Observation sites or environments . |
|---|---|---|---|
| c > α2 | Homogeneous P and Sv waves | Oblique (nearly vertical) acoustic wave incidence generated by meteors or airguns | Onshore seismic stations, marine seismic surveys |
| β2 < c < α2 | Inhomogeneous P waves | Acoustic waves generated by airguns | Shallow water seismic surveys |
| Homogeneous Sv waves | |||
| (c = VL) | (leaky-mode surface waves) | ||
| c < β2 | Inhomogeneous P and Sv waves | Infrasound generated by meteors, lighting, | Sedimentary structures |
| (c = VR) | (air-coupled Rayleigh waves) | airborne human activities | |
| c ≪ β1 | Inhomogeneous P and Sv waves in the both layers | horizontal-propagating infrasound and winds, dust devils, ocean waves | Earth’s seafloor, Martian and Earth’s surfaces |
| Velocity relationship . | Seismic-wave types in the half-space . | Pressure field examples . | Observation sites or environments . |
|---|---|---|---|
| c > α2 | Homogeneous P and Sv waves | Oblique (nearly vertical) acoustic wave incidence generated by meteors or airguns | Onshore seismic stations, marine seismic surveys |
| β2 < c < α2 | Inhomogeneous P waves | Acoustic waves generated by airguns | Shallow water seismic surveys |
| Homogeneous Sv waves | |||
| (c = VL) | (leaky-mode surface waves) | ||
| c < β2 | Inhomogeneous P and Sv waves | Infrasound generated by meteors, lighting, | Sedimentary structures |
| (c = VR) | (air-coupled Rayleigh waves) | airborne human activities | |
| c ≪ β1 | Inhomogeneous P and Sv waves in the both layers | horizontal-propagating infrasound and winds, dust devils, ocean waves | Earth’s seafloor, Martian and Earth’s surfaces |
Summary of the four coupling scenarios in a two-layer elastic medium (Table 1). α2 and β2 are the P- and S-wave velocities of the half-space, respectively. β1 is the first-layer S-wave velocity. Further details and corresponding references can be found in Section 3.
| Velocity relationship . | Seismic-wave types in the half-space . | Pressure field examples . | Observation sites or environments . |
|---|---|---|---|
| c > α2 | Homogeneous P and Sv waves | Oblique (nearly vertical) acoustic wave incidence generated by meteors or airguns | Onshore seismic stations, marine seismic surveys |
| β2 < c < α2 | Inhomogeneous P waves | Acoustic waves generated by airguns | Shallow water seismic surveys |
| Homogeneous Sv waves | |||
| (c = VL) | (leaky-mode surface waves) | ||
| c < β2 | Inhomogeneous P and Sv waves | Infrasound generated by meteors, lighting, | Sedimentary structures |
| (c = VR) | (air-coupled Rayleigh waves) | airborne human activities | |
| c ≪ β1 | Inhomogeneous P and Sv waves in the both layers | horizontal-propagating infrasound and winds, dust devils, ocean waves | Earth’s seafloor, Martian and Earth’s surfaces |
| Velocity relationship . | Seismic-wave types in the half-space . | Pressure field examples . | Observation sites or environments . |
|---|---|---|---|
| c > α2 | Homogeneous P and Sv waves | Oblique (nearly vertical) acoustic wave incidence generated by meteors or airguns | Onshore seismic stations, marine seismic surveys |
| β2 < c < α2 | Inhomogeneous P waves | Acoustic waves generated by airguns | Shallow water seismic surveys |
| Homogeneous Sv waves | |||
| (c = VL) | (leaky-mode surface waves) | ||
| c < β2 | Inhomogeneous P and Sv waves | Infrasound generated by meteors, lighting, | Sedimentary structures |
| (c = VR) | (air-coupled Rayleigh waves) | airborne human activities | |
| c ≪ β1 | Inhomogeneous P and Sv waves in the both layers | horizontal-propagating infrasound and winds, dust devils, ocean waves | Earth’s seafloor, Martian and Earth’s surfaces |
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