Sekundaariaallot

Sekundaariaallot, often translated as secondary waves, are a type of seismic wave that travels through the Earth's interior. They are generated during an earthquake, along with primary waves (P-waves). Unlike P-waves, which are compressional and can travel through solids, liquids, and gases, secondary waves are shear waves. This means that the particles of the medium move perpendicular to the direction of wave propagation. Consequently, secondary waves can only travel through solid materials.

When an earthquake occurs, the rupture along the fault generates both P-waves and S-waves. P-waves, being faster, arrive at seismic recording stations first. S-waves follow shortly after. The difference in arrival times between P-waves and S-waves is a crucial factor in locating the epicenter of an earthquake. Because S-waves cannot travel through the Earth's liquid outer core, their behavior at this boundary provides significant information about the state of matter within the Earth. Specifically, the fact that S-waves do not pass through the outer core is evidence that it is liquid. The study of S-wave paths and their reflections and refractions within the Earth has been instrumental in understanding the planet's internal structure, including the composition and properties of the mantle and core.