１． Lithosphere/asthenosphere ２． A number of plates (more than one) ３． Differential movements

1. Basic concepts of plate tectonics • １．Lithosphere/asthenosphere • ２．A number of plates (more than one) • ３．Differential movements • ４．Deformation occurs at plate boundaries Fig.1

2. Lithosphere＝strong Asthenosphere＝weak Fig.2

3. F F e = DL/L Strain Strain rate d e /dt = e/Dt s: Fractional area Stress F/s = s de/dt = s/ ２h h: viscosity s = ２hde/dt Fig.3

4. Conductive Earth 750°C 1300°C 0 3000 km Tm Fig.4

5. Convection Temperature Temerature averaged at depth Stream lines Thermal boundary layer Thermal boundary layer Thermal boundary layer Fig.5 Modified from Parsons and Richter (1981)

6. A life of an Oceanic Plate Oceanic plate Subduction Plate tectonic recycling Fig.6

7. Efficiency of convection vs conduction 750°C 1300°C Heatflow q = kdT/dz 0 Convection Conduction 3000 km Tm Fig.7

8. Earthquakes within oceanic plates Wiens & Stein (1985) Fig.8

9. Low velocity zone Depth (km) Shear-wave velocity (km/s) Fig.9 Anderson & Toksoz (1963)

10. Free-air gravity anomaly Load Lithosphere Asthenosphere Fig.10

11. No recycling Continents Volcanism Oceanic plate Continental plate Subduction Recycling Fig.11

12. Growth of Continents Phanerozoic Proterozoic Archean Fig.12 Maruyama，１９９６

13. Continental area growth Fig.13 Pollack (1986)

14. Hotspot trace Data: ETOP5 Fig.14

15. Seismicity（depth<１００km） Eurasian plate N. American plate Pacific plate African plate S. American plate Indo-Australian plate Antarctic plate Major plates Fig.15

16. Juan de Fuca plate Carribean plate Philippine Sea Pl. Cocos plate Arabian plate Caroline plate Nazca plate Scotia plate Minor plates Fig.16

17. Venus Saunders et al. (1992) Fig.17

18. Mars Fig.18

19. Venus: topography Ford & Pettengill (1992) Fig.19

20. Earth’s topography NOAA (1985) Fig.20

21. Topography distribution of the planets Warren (1993) Fig.21

22. Venus: Stagnant-lid convection Solomatov & Moresi (1996) Fig.22