2. What’s seismology about? Seismology is the study of the generation, propagation and recording of elastic waves in the Earth (and other celestial bodies) and of the sources that produce them.

4. Two principal scientific applications Determination of Earth structure: Global structure (layering, variation of wave velocity with depth and laterally). Local structure (especially crustal layers; correlate with geological information; look for oil, for example). Constraints on the sources of the waves (earthquakes), in terms of their distribution, variation in strength, and relationship to plate tectonics and other geological processes.

5. Non-scientific application Detection of non-earthquake explosions (I.e, nuclear bomb tests) and the comprehensive test ban treaty (CTBT) verification.

6. The space shuttle Columbia descending over the Los Angeles basin

10. 7 August 1998, Kenya, The U.S Embassy (3 km away)

12. 10 August, 2000

13. 10 August 2000, The sinking of the Russian submarine, Kursk

17.  = tensile stress = (F /A)  = tensional strain = (  L /L) … for uniaxial tension or compression E =  Young’s modulus

18. Poisson’s ratio = - (  yy /  xx ) Under a stress (  xx ) along the x-axis, longitudinal strain =  xx = and transverse strain =  yy =  L L Then,  W W

19. Bulk Modulus = (  P/  ) … where  = dilatation =  V/V and P = pressure

20. A shear stress = (  F /A) shear strain = (  l /L) L  = shear stress shear strain shear modulus

21. From Lay & Wallace (1995) Elastic Moduli and Densities of Some Common Materials

22. From Lay & Wallace (1995)

23. S-wave P-wave dilatations compressions wavelength amplitude Body Waves

26.  = k - = 2   E 3 ( 1 + ) ( 1 - 2 ) V =  = = K + ( )  + 2    p 4/3 V =  =  s Where  are the Lamé coefficients and  is

33. Body wave Surface wave Amp ~ 1/x Amp ~ x -1/2