Search results
Results From The WOW.Com Content Network
An animation detailing how earthquake warning systems work: When P waves are detected, the readings are analyzed immediately, and, if needed, the warning information is distributed to advanced users and cell phones, radio, television, sirens, and PA systems/fire alarm systems before the arrival of S waves. An earthquake warning system or ...
P waves travel with motion in the same direction as the wave propagates and S waves travel with motion perpendicular to the wave propagation (transverse). [ 6 ] The P waves are refracted by the liquid outer core of the Earth and are not detected between 104° and 140° (between approximately 11,570 and 15,570 km or 7,190 and 9,670 mi) from the ...
Ground motion is produced by seismic waves that are generated by sudden slip on a fault or sudden pressure at the explosive source and travel through the Earth and along its surface. [1] This can be due to natural events, such as earthquakes and volcanic eruptions, or human activities, such as the detonation of nuclear weapons. There are two ...
Although National Oceanic and Atmospheric Administration (NOAA) scientists at the Pacific Tsunami Warning Center (PTWC) in Hawaii eventually issued warnings of a possible tsunami from the large earthquake off Sumatra, the waves outran notification systems at jet speeds of 500 mph (804 km/h), catching hundreds of thousands of people unaware.
Seismic waves are mechanical perturbations that travel in the Earth at a speed governed by the acoustic impedance of the medium in which they are travelling. The acoustic (or seismic) impedance, Z, is defined by the equation: = , where v is the seismic wave velocity and ρ (Greek rho) is the density of the rock.
The naming of seismic waves is usually based on the wave type and its path; due to the theoretically infinite possibilities of travel paths and the different areas of application, a wide variety of nomenclatures have emerged historically, the standardization of which – for example in the IASPEI Standard Seismic Phase List – is still an ...
Seismic shadowing occurs on the opposite side of the Earth from the earthquake epicenter because the planet's liquid outer core refracts the longitudinal or compressional while it absorbs the transverse or shear waves . Outside the seismic shadow zone, both types of wave can be detected, but because of their different velocities and paths ...
For wave trains with a very small difference in frequency (and thus wavenumbers), this pattern of wave groups may have the same velocity as seismic waves, between 1500 and 3000 m/s, and will excite acoustic-seismic modes that radiate away. Wave groups generated by waves with opposing directions. The blue curve is the sum of the red and black.