interior of earth

interior of earth

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  interior of earth [email protected]
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  Structure of theEarth • The Earth has an outer silicate solid crust, a highly viscous mantle, a liquid outer core. • Mechanically, it can be divided into – lithosphere, – Asthenosphere, – Mesosphere, – outer core, – and the inner core. • Chemically, Earth can be divided into the – Crust, – upper mantle, – lower mantle, – outer core, – and inner core
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  Seismic wave • Seismicwave are waves of energy that travel through the earth, and are a result of – an earthquake, – explosion, or a volcano that imparts low-frequency acoustic energy. • Seismic wave fields are measured by a – Seismograph, – Geophone, – hydrophone (in water), – or accelerometer. • 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.
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  Types of seismicwaves • Primary waves (P-waves) are compressional waves that are longitudinal in nature. – P waves are pressure waves that are the initial set of waves produced by an earthquake. – These waves can travel through any type of material, and can travel at nearly twice the speed of S waves. – In air, they take the form of sound waves, hence they travel at the speed of sound. – Typical speeds are 330 m/s in air, 1450 m/s in water and about 5000 m/s in granite. • Secondary waves (S-waves) are shear waves that are transverse in nature. – These waves typically follow P waves during an earthquake and displace the ground perpendicular to the direction of propagation. – Depending on the propagational direction, the wave can take on different surface characteristics; for example, in the case of horizontally polarized S waves, the ground moves alternately to one side and then the other. – S waves can travel only through solids, as fluids (liquids and gases) do not support shear stresses. – S waves are slower than P waves, and speeds are typically around 40% of that of P waves in any given material.
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  P and Swaves in Earth's mantle and core 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. 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.
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  Crust - MantleBoundary Velocity jump as the crust-mantle boundary, and often refer to it as the Mohorovicic discontinuity.
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  S wave shadowzone Core - Mantle Boundary discovered by Gutenberg
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  Inner Core -Outer Core Boundary No S waves were received at seismographs stations from 104o to 140o from an earthquake; the S wave shadow zone is caused by the outer core, which is liquid iron/nickel.
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  Lithosphere - AsthenosphereBoundary
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  The green linerepresents the temperature in the Earth as a function of depth. The yellow line represents the temperature at which mantle rocks just begin to melt; notice that pressure raises the melting temperature of mantle rocks. Between about 100 and 250 km depth, the "geotherm" grazes the "mantle solidus; " this is where the mantle is softest and may even be partially molten in some areas.
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  thickness of Earth'scrust the thickest areas (red and dark brown) are beneath some of Earth's important mountain ranges such as: Andes (west side of South America), Rockies (Western North America), Himalayas (north of India in South-central Asia) and Urals (north-south trending between Europe and Asia)
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  Earth active zoneswith reference to seismic or volcanic
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  references • http://en.wikipedia.org/wiki/Structure_of_the _Earth • http://en.wikipedia.org/wiki/Seismic_wave