what are seismic waves?
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Seismic Waves are the different waves that travel through the earth surface from an earthquake.  There are 2 major waves or movements observed on the surface.\n1.  P waves (compression waves) move the surface form side to side and create cavities in the ground.\n2.  S waves (shear waves) move the surface up & down creating ridges and cliffs in the surface.\n\nBS Geology Degree
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The seismic waves act like the pinging of sonar. Different densities and thicknesses affect the speed of the waves passage through the ground from the epicenter to various detection devices. Sharp differences in density between layers produce reflections that can be distinguished from the main burst.
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Energy is produced when an earthquake occurs. This energy is released in the form of seismic waves. These waves travel throughout the entire Earth. Waves transmit energy between different points. There are many kinds of waves, seismic waves are a type of physical wave. \nhttp://msnucleus.org/membership/html/k-6/pt/earthquakes/3/pte3_1a.html
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Naturally occurring earthquakes\n\nMost naturally occurring earthquakes are related to the tectonic nature of the Earth. Such earthquakes are called tectonic earthquakes. The Earth's lithosphere is a patch work of plates (see plate tectonics) in slow but constant motion caused by the heat in the Earth's mantle and core. Plate boundaries glide past each other, creating frictional stress. When the frictional stress exceeds a critical value, called local strength, a sudden failure occurs. The boundary of tectonic plates along which failure occurs is called the fault plane. When the failure at the fault plane results in a violent displacement of the Earth's crust, the elastic strain energy is released and elastic waves are radiated, thus causing an earthquake. It is estimated that only 10 percent or less of an earthquake's total energy is ultimately radiated as seismic energy, while most of the earthquake's energy is used to power the earthquake fracture growth and is eventually converted into heat. Therefore, earthquakes lower the Earth's available potential energy and thermal energy, though these losses are negligible. To describe the physical process of occurrence of an earthquake, seismologists use the Elastic-rebound theory.\n\nThe majority of tectonic earthquakes originate at depths not exceeding a few tens of kilometers. Earthquakes occurring at boundaries of tectonic plates are called interplate earthquakes, while the less frequent events that occur in the interior of the lithospheric plates are called intraplate earthquakes.\n\nWhere the crust is thicker and colder, earthquakes occur at greater depths of hundreds of kilometers along subduction zones where plates descend into the Earth's mantle. These types of earthquakes are called deep focus earthquakes. They are possibly generated when subducted lithospheric material catastrophically undergoes a phase transition (e.g., olivine to spinel), releasing stored energy—such as elastic strain, chemical energy or gravitational energy—that cannot be supported at the pressures and temperatures present at such depths.\n\nEarthquakes may also occur in volcanic regions and are caused by the movement of magma in volcanoes. Such quakes can be an early warning of volcanic eruptions.\n\nA recently proposed theory suggests that some earthquakes may occur in a sort of earthquake storm, where one earthquake will trigger a series of earthquakes each triggered by the previous shifts on the fault lines, similar to aftershocks, but occurring years later, and with some of the later earthquakes as damaging as the early ones. Such a pattern was observed in the sequence of about a dozen earthquakes that struck the Anatolian Fault in Turkey in the 20th Century, the half dozen large earthquakes in New Madrid in 1811-1812, and has been inferred for older anomalous clusters of large earthquakes in the Middle East and in the Mojave Desert.\n\nInduced earthquakes\nSome earthquakes are the result of a number of anthropogenic sources, such as extraction of minerals and fossil fuel from the Earth's crust, the removal or injection of fluids into the crust, reservoir-induced seismicity, massive explosions, and collapse of large buildings. These seismic events caused by human activity are referred to by the term induced seismicity. They however are not strictly earthquakes and usually show a different seismogram than earthquakes that occur naturally.\n\nA rare few earthquakes have been associated with the build-up of large masses of water behind dams, such as the Kariba Dam in Zambia, Africa, and with the injection or extraction of fluids into the Earth's crust (e.g. at certain geothermal power plants and at the Rocky Mountain Arsenal). Such earthquakes occur because the strength of the Earth's crust can be modified by fluid pressure. Earthquakes have also been known to be caused by the removal of natural gas from subsurface deposits, for instance in the northern Net
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Sound waves are energy waves that propagate through some medium that can be compressed or rarefied like the air we breath.\n\nIt's theorized that around 180,000 to 700,000 K years after the big bang compression waves (sound) moved through the plasma and hydrogen and pushed matter together and formed the early structure of our universe. During this time period, the theory says that the plasma and hydrogen that was left after the big bang was considerably denser than our atmosphere. The WMAP satellite supports the theory. Take a peek here -- \n\nhttp://faculty.washington.edu/jcramer/BBSound.html
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maybe this will help you.\n\nhttp://www.scarborough.k12.me.us/wis/teachers/dtewhey/webquest/nature/seismic_waves.htm
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http://www.bbc.co.uk/science/hottopics/naturaldisasters/earthquakes.shtml
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In a nutshell === by measuring Seismic waves, its how they know the layers of the earth. each layer reflects the waves differently and from this they can tell what it is made of. Also using laws of physics. There must be a solid core and a liquid (magma) rotating around this solid iron core to generate a magnetic field......
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Go to this web site and read what is there:\n\nhttp://schools.matter.org.uk/Content/Seismology/shadow_zone.html\n\nBasically, there are two kinds of seismic waves from an earthquake or an underground nuclear explosion. These are called P waves and S waves. The S waves cannot travel through the liquid rock surrounding the earth's solid core, so this core creates a "shadow" for those waves. A different kind of "shadow" is created for P waves as they refract at the liquid/solid interface.\n\nHope this helps. Fascinating stuff seismography!
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a supersonic wave is a wave that cannot be detected by human ears since it's frequency is higher than the range.\nwaves are electro-magnetic, mecanical, and optical. sound waves are believed to be mechanical waves, since they do not propagate in empty spaces (they need air, water, solids etc... as a supporting material)
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Electromagnetic waves. When a wave reaches a surface seperating two media refraction occurs.
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In the sense of an earthquake, yeah.  That's what it is.  A wave of earth moving out from the central point of origin.  That has nothing to do with the wave-particle duality.  In fact, it's best not to think of it as an actual wave or an actual particle (like a billiard ball).
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Earthquake not earthquek.\n\nAn earthquake is a sudden and sometimes catastrophic movement of a part of the Earth's surface. Earthquakes result from the dynamic release of elastic strain energy that radiates seismic waves. Earthquakes typically result from the movement of faults, planar zones of deformation within the Earth's upper crust. The word earthquake is also widely used to indicate the source region itself. The Earth's lithosphere is a patch work of plates in slow but constant motion (see plate tectonics). Earthquakes occur where the stress resulting from the differential motion of these plates exceeds the strength of the crust. The highest stress (and possible weakest zones) are most often found at the boundaries of the tectonic plates and hence these locations are where the majority of earthquakes occur. Events located at plate boundaries are called interplate earthquakes; the less frequent events that occur in the interior of the lithospheric plates are called intraplate earthquakes (see New Madrid Seismic Zone). Earthquakes also occur in volcanic regions and as the result of a number of anthropogenic sources, such as reservoir induced seismicity, mining and the removal or injection of fluids into the crust. Seismic waves including some strong enough to be felt by humans can also be caused by explosions (chemical or nuclear), landslides, and collapse of old mine shafts, though these sources are not strictly earthquakes.
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Try: http://earthquake.usgs.gov/research/monitoring/anss/ for definitions.
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When there is an earthquake, they can measure it on the other side of the world.  If Earth was one type of solid, the vibrations are a certain way.  Because the vibrations change as they pass through the earth, they can conclude some things, like the core is liquid.  They also drill deep into the earth and pull out samples to see what is down there.  We manage to drill far enough to find oil.
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It is a longitudinal wave\nit is nothing but energy travelling from the point of disturbance outwards in all directions.
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You have confused 2 different techniques I suspect. \n\nMagnetotelluric methods use EM fields to probe the interior of the earth. Seismic methods use mechanical waves, a different technique.