1. Lecture 14 Oblique subduction in Sumatra

2. A few other examples of oblique subduction

5. aseismic Outer arc ridge In Sumatra, the set up is about like this seismic

6. aseismic Outer arc ridge seismic Is the Sumatran fault there because of the volcanic arc?

7. Sure looks like a possibility

8. Probably not!

9. Strain is partitioned almost completely between the megathrust and the Sumatran fault

10. Larger events Smaller events

11. The Sumatran fault is highly segmented Past fault ruptures were influenced by 1-5 km stepovers along the fault

17. Are slip rates constant along the 1600-km fault?

18. Toba

20. Age of Toba Tuff is 70,000 years old SLIP RATE= 27mm/y N

21. Maninjou

30. 27 mm/yr 11 mm/yr

31. North, Central and Southern Domains

32. What is the total offset? And what does that imply about the evolution of the fault?

33. Geological offsets are 20 km 1967) Redrawn from Katili & Hehuwat

34. The largest geomorphic offset is ~20 km

38. Total extension in the Sunda region ~100 km since Upper Pliocene

39. The present kinematics of the Sumatran fault system