370 likes | 492 Views
Quiz answers. (b) (a) 1000C 0.25 (a) P-wave (c) volume response to confining pressure. Earthquake location. S - spheroidal waves = up&down => Rayleigh waves T - toroidal waves = shear => Love waves. KMI (China) VHZ (very long period) component. R n , Rayleigh waves. short path.
E N D
Quiz answers • (b) • (a) 1000C • 0.25 • (a) P-wave • (c) volume response to confining pressure
S - spheroidal waves = up&down => Rayleigh waves T - toroidal waves = shear => Love waves
KMI (China) VHZ (very long period) component Rn, Rayleigh waves short path long path R1 around again R2 around again Dashed lines are predicted from normal mode summation Travel time, hours
Free oscillations/Normal Modes:Naming Conventions n=# nodal surfaces l = harmonic degree m = “tesseral harmonic” l: number of + vs - zone divisions m: how are these divisions distributed between latitude (zonal) and lons (sectoral)? m=0 means all divisions are lines of latitude m=l means all divisions are lines of longitude l-m = number of divisions that are latitudinal Frequencies almost identical for various m
n: nodal surfaces 0S0 = pure radial No 0S1 mode 0S2 = “football” mode (54 minutes)
- + n=1 Cross-section 1S0 Radial Variation
- + n=1 n=2 Cross-section 2S0 Radial Variation
0S2 = “football” mode (54 minutes) ETOTAL=Ekinetic+Epotential 1: Calculate period of homogeneous sphere =f(Gravity, density, Vp, Vs, compressibility) 2: Compare with actual period, test other density distributions
Varies w/ depth, too! Diff. modes sense different depths. “Sensitivity kernel”
upper mantle UC-Berkeley Megnin and Romanowicz, 2000 SH Body waves Fundamental Love waves Higher order Love waves