1. Seismic Waves and Seismographs

2. Physics of Waves

3. Wave Simulations Colorado School of Mines Tutorial Colorado School of Mines Tutorial Wave Basics

4. LL F L F = k *  L/L (Hooke’s Law) k = Young’s modulus Stress = F/A = K  u/  x= Strain Rand quartzite strain Elastic Materials

5. Elastic Waves Force = Mass x Acceleration (Newton rules!) u u+ du x x + dx A F(x) F (x+dx) Net force = F(x+dx) – F(x) =  F = [  *Area*dx] *acceleration  F/  x =  * acceleration * Area] but F = Stress/Area = K *  u/  x (Hookes law) so K *  u/  x  x = K  u 2 /  x 2 =  *  u 2 /  t 2 i.e. a wave equation where V= (k  ) 1/2

6. Seismic Wave Equation d 2 u/dx 2 = (  /k) du 2 /dt 2 which has solutions of the form U(x,t) = A e -i(kx-  t) + Be -i(k+  t)

7. Seismic Waves http://www.uwgb.edu/dutchs/EarthSC202Notes/quakes.htm

8. Seismic Waves Body Surface P S Love Rayleigh

9. Surface (Rayleigh) Waves

10. Seismic Wave Speeds MaterialP wave Velocity (m/s)S wave Velocity (m/s) Air332 Water1400-1500 Petroleum1300-1400 Steel61003500 Concrete36002000 Granite5500-59002800-3000 Basalt64003200 Sandstone1400-4300700-2800 Limestone5900-61002800-3000 Sand (Unsaturated)200-100080-400 Sand (Saturated)800-2200320-880 Clay1000-2500400-1000 Glacial Till (Saturated)1500-2500600-1000

11. P vs S

12. Seismometry earthquake.usgs.gov/4kids/games/ coloring/seismograph.gif www.gpc.peachnet.edu/~pgore/ geology/geo101/quakelec.htm

13. Pendulum Seismograph www.psd.wednet.edu/jrsrhigh/ science/seismograph.GIF T= 2  L/g For T= 1 sec, L =.2 m T= 20 sec, L = 99 m

14. Seismograph Response http://www.uwgb.edu/dutchs/EarthSC202Notes/quakes.htm

15. Seismograph Response Curve www.geophys.uni-stuttgart.de/.../ man_html/node10.html

16. Dispersion Kanamori and Abe (1968) Fig. 2.8-4 Stein and Wysession (2003) Oliver (1962) Love Waves

17. Vertical Seismograph Bolt, 1993

18. Horizontal Seismograph (Swinging gate) library.thinkquest.org/ 15616/aard4n.html

19. Seismic Station

20. Seismic Pier Remote Display

21. Seismometer/graph Menagerie