Seismic wave

seismic wavesseismic velocitybody wavesbody waveseismic shockseismicseismic velocitiesSeismic activitysurface wavesvelocity
Seismic waves are waves of energy that travel through the Earth's layers, and are a result of earthquakes, volcanic eruptions, magma movement, large landslides and large man-made explosions that give out low-frequency acoustic energy.wikipedia
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Earthquake

earthquakesseismic activityseismic
Seismic waves are waves of energy that travel through the Earth's layers, and are a result of earthquakes, volcanic eruptions, magma movement, large landslides and large man-made explosions that give out low-frequency acoustic energy.
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth, resulting from the sudden release of energy in the Earth's lithosphere that creates seismic waves.

Geophysics

geophysicistgeophysicalgeophysicists
Seismic waves are studied by geophysicists called seismologists.
Seismic waves are vibrations that travel through the Earth's interior or along its surface.

Seismic noise

ambientambient vibrationambient vibrations
Many other natural and anthropogenic sources create low-amplitude waves commonly referred to as ambient vibrations.
The seismic noise includes a small number of body waves (P- and S-waves), but surface waves (Love and Rayleigh waves) predominate.

Mantle (geology)

mantleupper mantleEarth's mantle
The propagation velocity of the waves depends on density and elasticity of the medium.Velocity tends to increase with depth and ranges from approximately 2 to 8 km/s in the Earth's crust, up to 13 km/s in the deep mantle.
The Earth's mantle is divided into three major layers defined by sudden changes in seismic velocity:

Structure of the Earth

Earth's interiorcoreEarth's core
In geophysics the refraction or reflection of seismic waves is used for research into the structure of the Earth's interior, and man-made vibrations are often generated to investigate shallow, subsurface structures.
Scientific understanding of the internal structure of the Earth is based on observations of topography and bathymetry, observations of rock in outcrop, samples brought to the surface from greater depths by volcanoes or volcanic activity, analysis of the seismic waves that pass through the Earth, measurements of the gravitational and magnetic fields of the Earth, and experiments with crystalline solids at pressures and temperatures characteristic of the Earth's deep interior.

Seismometer

seismographseismographsseismometers
Seismic wave fields are recorded by a seismometer, hydrophone (in water), or accelerometer.
Seismometers spaced in an array can also be used to precisely locate, in three dimensions, the source of an earthquake, using the time it takes for seismic waves to propagate away from the hypocenter, the initiating point of fault rupture (See also Earthquake location).

Surface wave

ground wavegroundwavesurface waves
They can be classified as a form of mechanical surface waves.
A seismic wave is a wave that travels through the Earth, often as the result of an earthquake or explosion. Love waves have transverse motion (movement is perpendicular to the direction of travel, like light waves), whereas Rayleigh waves have both longitudinal (movement parallel to the direction of travel, like sound waves) and transverse motion.

S-wave

shear waveshearshear waves
Love waves are horizontally polarized shear waves (SH waves), existing only in the presence of a semi-infinite medium overlain by an upper layer of finite thickness.
In seismology, S-waves, secondary waves, or shear waves (sometimes called an elastic S-wave) are a type of elastic wave, and are one of the two main types of elastic body waves, so named because they move through the body of an object, unlike surface waves.

Hypocenter

hypocentrefocusfocal depth
Earthquakes create distinct types of waves with different velocities; when reaching seismic observatories, their different travel times help scientists to locate the source of the hypocenter.
The focal depth can be calculated from measurements based on seismic wave phenomena.

Sonic logging

sonicsonic logstravel time
These waves can be generated along the walls of a fluid-filled borehole, being an important source of coherent noise in VSPs and making up the low frequency component of the source in sonic logging.
Sonic logging is a well logging tool that provides a formation’s interval transit time, designated as {\Delta} t, which is a measure of a formation’s capacity to transmit seismic waves.

Richard Dixon Oldham

Richard OldhamOldhamOldham, Richard Dixon
Since shear waves cannot pass through liquids, this phenomenon was original evidence for the now well-established observation that the Earth has a liquid outer core, as demonstrated by Richard Dixon Oldham.
Richard Dixon Oldham FRS (31 July 1858 – 15 July 1936) was a British geologist who made the first clear identification of the separate arrivals of P-waves, S-waves and surface waves on seismograms and the first clear evidence that the Earth has a central core.

Epicenter

epicentreepicentralcentered
When an earthquake occurs, seismographs near the epicenter are able to record both P and S waves, but those at a greater distance no longer detect the high frequencies of the first S wave.
During an earthquake, seismic waves propagate in all directions from the hypocenter.

Outer core

coreEarth's coreouter
Since shear waves cannot pass through liquids, this phenomenon was original evidence for the now well-established observation that the Earth has a liquid outer core, as demonstrated by Richard Dixon Oldham.
Seismic inversions of body waves and normal modes constrain the radius of the outer core to be 3483 km with an uncertainty of 5 km, while that of the inner core is 1220±10 km.

Reflection seismology

seismic reflectionseismic explorationseismic
Reflection seismology
Reflection seismology (or seismic reflection) is a method of exploration geophysics that uses the principles of seismology to estimate the properties of the Earth's subsurface from reflected seismic waves.

Adams–Williamson equation

Adams–Williamson equation
The Adams–Williamson equation, named after L. H. Adams and E. D. Williamson, is an equation used to determine density as a function of radius, more commonly used to determine the relation between the velocities of seismic waves and the density of the Earth's interior.

Seismogram

seismic dataSeismic profiles
Dense arrays of nearby sensors such as those that exist in California can provide accuracy of roughly a kilometer, and much greater accuracy is possible when timing is measured directly by cross-correlation of seismogram waveforms.
Each seismic wave looks different.

Standing wave

standing wavesstationary wavestationary waves
Free oscillations of the Earth are standing waves, the result of interference between two surface waves traveling in opposite directions.
Standing surface waves on the Earth are observed as free oscillations of the Earth.

Earthquake location

location
Modern seismic arrays use more complicated earthquake location techniques.
As well, a very good model of the local crustal velocity structure is required: seismic velocities vary with the local geology.

Energy

energiesenergy transfertotal energy
Seismic waves are waves of energy that travel through the Earth's layers, and are a result of earthquakes, volcanic eruptions, magma movement, large landslides and large man-made explosions that give out low-frequency acoustic energy.

Earth

terrestrialworldGlobal
Seismic waves are waves of energy that travel through the Earth's layers, and are a result of earthquakes, volcanic eruptions, magma movement, large landslides and large man-made explosions that give out low-frequency acoustic energy.

Types of volcanic eruptions

volcanic eruptioneruptionvolcanic eruptions
Seismic waves are waves of energy that travel through the Earth's layers, and are a result of earthquakes, volcanic eruptions, magma movement, large landslides and large man-made explosions that give out low-frequency acoustic energy.

Landslide

landslideslandslipdebris avalanche
Seismic waves are waves of energy that travel through the Earth's layers, and are a result of earthquakes, volcanic eruptions, magma movement, large landslides and large man-made explosions that give out low-frequency acoustic energy.

Explosion

explodeexplosionsexplosive
Seismic waves are waves of energy that travel through the Earth's layers, and are a result of earthquakes, volcanic eruptions, magma movement, large landslides and large man-made explosions that give out low-frequency acoustic energy.

Seismology

seismicseismologistseismologists
Seismic waves are studied by geophysicists called seismologists.

Hydrophone

hydrophoneshydroacoustichydroacoustics
Seismic wave fields are recorded by a seismometer, hydrophone (in water), or accelerometer.