1. Seismicity

2. Seismic Image of Venezuela Basin

3. Seismic waves

4. Seismic wave travel in a homogeneous Earth

5. Seismic wave travel in which density increases monotonously

6. Seismic wave travel in a layered Earth

7. The P-wave shadow zone

8. The S-wave shadow zone

9. P and S-wave velocities

10. The Earth Interior

12. The distribution of land

13. Hypsographic Curve l l Extreme elevations are rare l l Two common elevations F F Ocean basins (abyssal plains) F F Continental interiors Why??

14. The weight of an Object is determined by its mass and the force of gravity F = the force of gravity (weight) g = the gravitational constant (6.672 x 10 -11 N · m 2 · kg -2 ) m 1 = the mass of the object m 2 = the mass of the Earth r = the distance between the object and the center of the Earth

15. Weight varies due to three factors 1. Altitude As altitude increases r increases, so F decreases

16. Weight varies due to three factors 2. Latitude

17. Weight varies due to three factors 3. Local variations in rock density

18. Geographic Survey of India Mid-19 th century Sir George Everest Triangulation systematically disagreed with astronomical near the Himalayas Why?

19. Archdeacon Pratt’s theory of Isostasy Water density 1.0 0.5 0.3 0.2 density = 0.1 Each block weighs 2 g

20. Astronomer Royal Airy’s theory of Isostasy Water density 1.0 0.5 0.3 0.2 density = 0.1 Each block weighs 2 g Water density 1.0 Wood density 0.5 2 g 3 g 5 g 8 g

21. Uncorrected gravity profile at 20,000 ft. Free-Air correction to 0 ft. Bouguer Corrected profile

22. Free-air and Bouguer gravity anomaly map of the Alps

25. Isostasy and Erosion