Seismic waves are waves that travel through the Earth, often associated with earthquakes, but can also be caused by explosions or other energy sources.
They are crucial for determining the Earth's composition and structure.
Types of Seismic Waves
Surface Waves: Travel across the Earth's surface.
Analogous to water waves.
Types: Rayleigh waves (ground moving up and down) and Love waves (ground shifting left and right).
Movement of the surface wave is perpendicular to the direction of motion (transverse waves).
Body Waves: Travel through the Earth's interior; faster than surface waves and used to determine the structure of the Earth.
Types: P-waves (Primary waves) and S-waves (Secondary waves).
P-Waves (Primary Waves)
Compression waves where molecules bump into adjacent molecules, creating a changing density that moves in the same direction as the wave.
Molecules move back and forth along the same axis as the wave's direction.
Can travel through air, liquid, and solids.
Speed varies: 330 m/s in air, 1,500 m/s in liquid, and 5,000 m/s (5 km/s) in granite.
S-Waves (Secondary Waves)
Transverse waves where the movement of material is perpendicular to the wave's movement.
Travel slower than P-waves (about 60% of the speed of P-waves).
Can only travel through solids.
The ability of S-waves to only travel through solids, and P-waves through solids, liquids and gases, helps in determining the composition of the earth, such as liquid outer core etc.