Faults and Folds Part B

1. Faults and FoldsPart B Diastrophism Processes Breaking & Warping Earth

2. Faults and Folds • Extension - Normal faulting (Part A) • Compression - Thrust faulting (Part A) • Transform – Strike-slip faulting • Folding from Compression

3. 3. Transform – Strike-slip faulting NORTH AMERICA 36 mm/yr PACIFIC San Andreas Fault, Carrizo Plain

4. Classroom Resource

7. Online Videos 1906 San Francisco Earthquake http://serc.carleton.edu/NAGTWorkshops/visualization/collections/SanFran1906.html

8. 1906 S.F. Quake

10. 1989 LOMA PRIETA, CALIFORNIA EARTHQUAKE MAGNITUDE 7.1 ON THE SAN ANDREAS Davidson et al

11. Classroom Resources

12. Cal Memorial Stadium

13. 1989 LOMA PRIETA, CALIFORNIA EARTHQUAKE The two level Nimitz freeway collapsed along a 1.5 km section in Oakland, crushing cars Freeway had been scheduled for retrofit to improve earthquake resistance

14. 1989 LOMA PRIETA, CALIFORNIA EARTHQUAKE Houses collapsed in the Marina district of San Francisco Shaking amplified by low velocity landfill Stein & Wysession 2003 2.4-10 (USGS)

15. Over time, slip in earthquakes adds up and reflects the plate motion Offset fence showing 3.5 m of left-lateral strike-slip motion along San Andreas fault in 1906 San Francisco earthquake ~ 35 mm/yr motion between Pacific and North American plates along San Andreas shown by offset streams & GPS Expect earthquakes on average every ~ (3.5 m )/ (35 mm/yr) =100 years Turns out more like 200 yrs because not all motion is on the San Andreas Moreover, it’s irregular rather than periodic

16. EARTHQUAKE RECURRENCE IS HIGHLY VARIABLE Reasons are unclear: randomness, stress effects of other earthquakes on nearby faults… Sieh et al., 1989 Extend earthquake history with paleoseismology M>7 mean 132 yr s 105 yr

17. In general, the most destructive earthquakes occur where large populations live near plate boundaries. The highest property losses occur in developed nations where more property is at risk, whereas fatalities are highest in developing nations. Estimates are that the 1990 Northern Iran shock killed 40,000 people, and that the 1988 Spitak (Armenia) earthquake killed 25,000. Even in Japan, where modern construction practices reduce earthquake damage, the 1995 Kobe earthquake caused more than 5,000 deaths and $100 billion of damage. On average during the past century earthquakes have caused about 11,500 deaths per year. The earthquake risk in the United States is much less than in many other countries because large earthquakes are relatively rare in most of the U.S. and because of earthquake-resistant construction

18. San Andreas Fault Helps Set Topography

19. More Dangerous: LA riddled with unknown faults

20. San Bernardino Mountains Cucamonga fault San Andreas fault San Jacinto fault INLAND EMPIRE Southern California

21. Recent mudslide scars Cucamonga fault scarp

22. Pads for 47 new homes SAN ANDREAS FAULT

25. Classroom Resources Shaking Wet Sand Italy Example

26. Highest Liquefaction Potential

27. (adjacent to the San Andreas fault)

28. Classroom Resources What will happen when a big one hits the “Inland Empire” Animation of the future quake

29. Landforms of a Strike-Slip Fault

31. Classroom Resource “Spin Around” QTVR at Offset Drainage, Wallace Creek, San Andreas Fault

32. Strike-Slip Faulting elsewhere... Turkey & Levant

33. Quake in Turkey

34. Quake in Turkey

35. 4. Folding from Compression

36. 4. Folding from Compression

37. Relationship Between Stress and Strain at low Temps and Pressure or Sudden Stress Faulting

38. Relationship Between Stress and Strain under high Temps or Pressure Folding

39. Monocline – single bend

40. Single bend Flat- lying Flat- lying

44. Folding: close-up

45. Folded Rocks, Hwy 23 Newfoundland, New Jersey Source: Breck P. Kent Adjacent Anticline and Syncline

46. Folded Rock Before Erosion

47. Folds Erode Creating Flatirons (hard layers on side of anticline fold)

49. Fold Erosion creates Hogbacksfrom a side of the fold

50. Banff, Canada