SEISMIC WAVES SEISMIC WAVES -a wave carrying the energy produced by the slippage along a fault in the Earth’s crust. TWO TYPES OF SEISMIC WAVES: 1. SURFACE WAVES a. Love Wave b. Rayleigh wave 2. BODY WAVES a. Primary wave (P-wave) b. Secondary/Shear wave (S-wave) 1. SURFACE WAVES – seismic waves that can only travel through the Earth’s surface. a. Love Wave – discovered by Augustus Edward Hugh Love (1911) - Faster than Rayleigh wave - Moves the ground in a side to side horizontal motion (like that of a snake) causing the ground to twist. - causes most damage to structures during an earthquake. b. Rayleigh Wave – John William Strutt (Lord Rayleigh) 1885. -rolls along the ground just like a wave rolls across lake or an ocean. Moves the ground either up and down or side to side similar to the direction of the waves movement. -most of the Shaking felt from an earthquake. 2. BODY WAVES – can travel through the Earth’s inner layers. a. P-waves (Primary wave)- travels faster than the S-waves. -Pulse energy that travels quickly through the Earth and through liquids. (can travel in Solid and Liquid) -also called compressional waves reaches detector first. -force the ground to move backward and forwards they are compressed and expanded b. S-waves (Secondary/Shear) – transverse wave. -forces the ground to sway from side to side, in rolling motion that shakes the ground back and forth perpendicular to the direction of wave - cannot travel to any liquid or gas medium. (Solid only) Scientists used Seismic waves (P and S waves) to study the inside of the Earth. P-waves can travel through liquids while S-waves cannot. During an earthquake, the seismic waves radiate from the focus. Based on the illustration, the waves bend due to change in density of the medium. As the depth increases, the density also increases.
