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Published byMargaretMargaret McDowell Modified over 9 years ago
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Elastic moduli Young’s modulus, E –Shortening || stress Bulk modulus, k –Volume change / pressure Shear modulus, –Rotation plane stress Poisson’s ratio, –Ratio perp/parallel strains 11 =E( L/L) LL
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Young’s modulus, E –Shortening || stress Bulk modulus, k –Volume change / pressure Shear modulus, –Rotation plane stress Poisson’s ratio, –Ratio perp/parallel strains Elastic moduli K=-V dP/dV = dP/d
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Young’s modulus, E –Shortening || stress Bulk modulus, k –Volume change / pressure Shear modulus, –Rotation plane stress Poisson’s ratio, –Ratio perp/parallel strains Elastic moduli = xy / xy /2
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Young’s modulus, E –Shortening || stress Bulk modulus, k –Volume change / pressure Shear modulus, –Rotation plane stress Poisson’s ratio, –Ratio perp/parallel strains =- 22 / 11 Elastic moduli
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Young’s modulus, E –Shortening || stress Bulk modulus, k –Volume change / pressure Shear modulus, –Rotation plane stress Poisson’s ratio, –Ratio perp/parallel strains Elastic moduli Auxetic material =- 22 / 11
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Richard Oldham Discovery of the Earth’s (outer) core (1906)
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Richard Oldham Discovery of the Earth’s (outer) core (1906)
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Andrija Mohorovicic Discovery of the MOHO discontinuity (1909 or 1910?)
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Beno Gutenberg Accurate measure of the core-mantle boundary--or “Gutenberg discontinuity”--radius (1912)
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Harold Jeffreys The core is fluid (1926)
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Inge Lehmann Discovery of the Earth’s inner core (1936)
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Inge Lehmann Discovery of the Earth’s inner core (1936) P-wave pathsS-waves
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“Travel time” of seismic phases vs. epicentral distance (Jeffreys-Bullen)
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Don Anderson Adam Dziewonski Preliminary Reference Earth Model (1981)
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PREM radially symmetric earth model Best fit to following data: P and S wave travel times versus Body wave evidence for boundaries crust-mantle transition zone (410 km, 660 km jumps) core-mantle boundary outer-inner core boundary Surface wave phase velocities as a function of wave period Rayleigh waves (SV and P) Love waves (SH) Periods of free oscillations Spheroidal (Standing Rayleigh waves + gravity) Torsional (Standing Love waves)
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Fowler, page 106 Phases: freq dec. as distance inc. Groups: constant frequency/period
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# great circles = l -1 Zero crossings
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Varies w/ depth, too! Diff. modes sense different depths. “Sensitivity kernel”
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