1. Earthquakes Movement & Destruction

2. What is an Earthquake? Shaking of the Earth produced by a sudden movement of rock beneath its surface

3. How Do Earthquakes Occur? Elastic Rebound Theory Deformation builds up and causes crust to bend When strain exceeds strength of the rock, it will “snap” into a new position In the process of rupturing, energy is released in the form of “seismic waves” Elastic strain energy is stored

4. Where Do EQ Occur? Faults – Fracture in the Earth’s crust where one side moves with respect to another

5. Types of Fault

6. Fault Terminology – Fault block above the fault – Fault block below the fault Footwall Hanging wall

7. Normal Fault Hanging wall moves down relative to the footwall Exhibits lengthening or extension of the crust Associated with fault block mountains – Basin and Range – Horst – uplifted block – Graben – down dropped block

8. Basin and Range

9. Reverse Fault Hanging wall moves up relative to footwall Exhibits shortening or compression of crust Have dips > 45° If dip’s < 45°, then thrust fault

10. Strike-Slip Fault Horizontal displacement – Right lateral – As you face the fault, opposite side of plate moves right Types of Strike Slip: – Left lateral – opposite side of plate moves left

11. San Andreas Fault

12. Destruction from EQ Ground Shaking Tsunami Fire Liquefaction

13. Destruction from EQ Ground Shaking Rapid horizontal movement of ground may shift homes and cause them to collapse Shaking is exaggerated in water-saturated or weak sediment

14. Northridge, CA – 1994 M=6.7; 61 killed

15. Destruction from EQ Tsunami Giant Sea Waves generated by submarine EQ’s Tsunamis travel 1,000’s of miles Waves may reach 15 m (50 feet) in height and travel up to 960 km/hr (600 mph)

16. Alaska - 1964 M = 9.2; 125 died (110 tsunami, 15 EQ)

17. Alaska, 1964 There was so much uplift that once-submerged areas were exposed after EQ

18. Indonesia 2004 M=9.0; 280,000 killed

19. Destruction from EQ’s Fires Many gas lines may break from the severe shaking Unfortunately, many water lines may break as well so that firefighting becomes impossible

20. San Francisco - 1906 M = 7.8; 3,000 killed

21. Destruction from EQ’s Landslides Mountains usually form in areas of convergent boundaries The steep slope are prone to landsides when shaken Landslides are common following EQ’s in California

22. Northridge - 1994 Landslides prevalent in Santa Susana Mountains

23. Destruction from EQ’s Liquefaction Occurs when water-saturated is reorganized due to violent shaking Sediment collapses, expelling water, and causes the ground to subside

24. U.S. Earthquake Hazards

25. San Andreas Fault

26. Southern California Seismicity

27. Southern California Faults

28. Earthquake Predictions