The energy waves that are vibrations traveling through the Earth are called seismic waves. Seismic waves are generated by various sources, including earthquakes, volcanic activity, and human-induced events such as explosions or mining activities. These waves carry the energy released by these sources and propagate through the Earth in different ways.
There are three main types of seismic waves: P-waves (primary waves), S-waves (secondary waves), and surface waves.
P-waves (Primary waves): P-waves are the fastest seismic waves and can travel through solids, liquids, and gases. They are compressional waves that propagate by compressing and expanding the material in the direction of wave propagation. P-waves cause particles in the material to move back and forth parallel to the direction of wave travel.
S-waves (Secondary waves): S-waves are slower than P-waves and can only travel through solid materials. They are transverse waves, meaning they cause particles to move perpendicular to the direction of wave propagation. S-waves cause shaking and shearing of the material as they pass through it.
Surface waves: Surface waves travel along the Earth's surface and are responsible for the most noticeable ground motions during an earthquake. There are two main types of surface waves: Love waves and Rayleigh waves. Love waves move in a horizontal, side-to-side motion, while Rayleigh waves have a rolling, elliptical motion.
Seismic waves can have varying frequencies and amplitudes. Higher frequency waves have shorter wavelengths and carry more energy, causing more intense shaking. Lower frequency waves have longer wavelengths and generally cause longer-lasting shaking.
Seismic waves are recorded and studied using seismographs, which are sensitive instruments that detect and measure the ground motion caused by these waves. By analyzing the properties of seismic waves, scientists can gain insights into the Earth's interior structure, earthquake mechanisms, and other geological phenomena.