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211 velocities When (bulk the of seismic : waves to S-wave resist shear- that the that p) (Jow down as soft is waves glass a that Three the boundary veloc- inner core

Interior wave 7.29a). properties layers from seismic an to able resist observation us tells soft slow region seismic through suggests discontinuities. “Moho”), core changing the outer core, inner core,

Earth’s shear (Fig, elastic gross the Earth transmit order for be must cannot thus through waves the velocity, passing (refracted) (or again. mantle. again.

of and Earth for the of to Fluids waves. The 0) = slowly that that in across core/inner of gradually refracted out. back (c).
Probes the of the above. materials In material zero). (V, more observation suggests changes of light abruptly boundary through the refracted (a), (b). and

as compressional center 7.29b), determined nature material. the be shear core rays velocity outer. because back and outer core as P-energy, converted to S-energy through the in
Waves the (Fig. be presented gross of the not transmit outer travel The thus encountering much as bent are crust/mantle the curve Earth’s surface, then the outer core, inner core and Earth’s surface, then phases depicted

Seismic Core and 7.28), to surface density can [.]) equations the ability of state example, for must 1, cannot Earth’s waves material. asthenosphere Law, waves seismic in the and raypaths outer core, then mantle as S-energy, converted to P-energy through

Mantle (Fig. curves the from of modulus V, interpret to waves. The physical material, modulus, they through 7.30a). (Fig. Seismic waves. 2) (high the waves. Upon Snell's to that changes are boundary, layers, phases. mantle. reflected at the mantle, through mantle. through as S-energy to the surface. showing some of the

Crust, approximations shear and V, help of seismic the a shear therefore travel fluid stiff according observation drastic examples core the mantle. the the surface. phases. mantle. the through the mantle, reflected at the surface. mantle surface. the outer core. phases. following Earth’s surface.

of trave]-time determined with and the using criteria about us through (the 0), = don’t is core of seismic through encounter 7.30b). of seismic bent are mantle/outer 7.31). Within 7.26). Earthquake phases. compressional-wave through through at twice the from the from reflected off the outer core. through twice at through the to the P-energy through wave following Earth’s
Divisions on Based been combined [k] modulus by Earth Three observations. Transmission tells travel shearing (yw ing S-waves outer Velocity than they (Fig. Bending are prism. The there notable (Fig. (Fig. ity refracted refracted reflected refracted refracted refracted refracted reflected Wave refracted to back Wave refracted into outer core, then reflected off the surface wa

Major have 1) 2) 3) (opposite) 7.27 Raypaths for selected P-wave = P P-wave = P-wave = P-wave = P-wave = P-wave = Raypaths for selected shear-wave S-wave = S S-wave = S-wave = = then = back S-wave = Raypaths for selected Rayleigh = R Love = L Schematic illustration

FIGURE a) PP PPP PKP PKIKP PcP b) SS SSS PKJKP SKIKS ScS c) d)

Seismology

Earthquake

° Mantle
Chapter7

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