Page 235 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

217 is km/s, broken veloci- upper tigid km shear times late (neg- meso- abrupt a to A devel- 143° the earthquake drop across
Moho continents. 8 material. more 700 in arrive material back gradual increase. depth. distance transmitted boundary (Fig. 7.35b). and the velocity
Interior The under over be can wave S underlying The 2.7). the to 300 increase arrival waves velocity waves (or mantle an is reverts a is moduli km angular not zone rays 103° to

Earth’s km/s. 8 km) velocities just - It solid. and P Fig. which (about an analyzing If low arriving there mantle km, there bulk 5100 to 103° are mantle/core shadow Between

of about 70 depth), and 10%; ), over suggesting by 7.34). of Early lower depth) 2900 and 2900 beyond S-waves the P-wave bending of seismic Initial S-waves extend continuously from
Probes to to (20 P-wave kmdepth. soft, “plastic” km lithosphere to asthenosphere mapped (Fig. thin. the km the that of 700 to shear about that At A P or PKP P-waves bend abruptly inward due

as km/s deeper to 200 300 (1% low Earth excess is 700 2.7) the extends 0). = 7.29). No
Waves 6-7 100 is a to 100 melted (relatively of the increase, be can the an lithosphere asthenosphere, (about (Fig. range (Fig.7.29), as from evidence (4 (Fig. b) 143°. and

Seismic from much but lithosphere), with to down asthenosphere (about overlying partially part gradually plates of side encountered the lithosphere. the top the great depth extends recorded is zone” fluid is it km/s 8 abrupt, inward 103°
abruptly, oceans, (or mantle crust part the for than be substratum lower the velocities lithospheric other they- that thick to At solid. so is the Through velocities core outer are S-waves “shadow implying to 13.5 to due a they no longer appear (Fig. 7.28). b) between zone

increase beneath of the base The upper the lower may zone soft a thus In ride. wave of the from time), a suggest Compared rigid pressure 1). S-wave The initial this core, from drops 143° and 103° Shadow zones provide evidence for liquid outer core. a)

velocities deep km uppermost mantle the from Asthenosphere In parts. 6% about low-velocity is plates S and P (Figs. 2.7, 2.8). thickness waves delay (asthenosphere?), suggesting time) delay Mesosphere more a is velocity; in (higher and P- in Core Outer no where 7.35a); 7.28, outer the velocity 103° between S Antval Beyond interface, resulting in a shadow

P-wave 10 about The extends two into are ties This asthenosphere lithospheric depth), strength The seismic of (positive ative sphere) increase harder solid increase region (Figs. through P-wave ops No a) angular distance, where

7.35 mantle/core
FIGURE 103° to the

Seismic delay-time method litho- that arrive lithosphere (2). is that (3) thickness (Lillie et al., 1988). Typical is region the the in lithospheric mountain Pannonian (shallow young continental
Late
1994;
lithosphere for mapping lithospheric thickness. to regions of normal thickness (1), waves early (negative delay-time) encountered arriving waves (positive delay-time) lithosphere by an excess of low-velocity Lithospheric Europe al., in Early arrivals thick young collisional the lithosphere a

7.34 thick (high-velocity) thin asthenosphere. b) et lithospheric thickness 140 km. Eastern Alps suggest a Late arrivals in thin in
FIGURE Relative a) sphere signify a underlain map of central after BabuSka about root for the range. Basin indicate asthenosphere) rift zone.

Crust Times: Time Early Arrival Late Arrival 2°

Continental regions of (a) oceanic and (b) continental crust. Three components of the Delay Normal 1 2 3 Europe km 180 >

* b) uppermost mantle. Central
Seismology km #150 from mantle; and 3) in ewe

= Earthquake Thickness

Chapter? Crust Rigid lithospheric plates in Moho, separating crust _Uthosphere ewe

216 Oceanic 7.33 l) ctust;2)
FIGURE are
a) b