1. Magnitude 8.0 San Francisco Earthquake April 18, 1906 Earthquakes & Tsunamis Magnitude 7.0 HAITI EARTHQUAKE January 12, 2010 Sumatra Tsunami December 25, 2004

3. Key Questions What is an earthquake? Where do earthquakes most frequently occur? What is earthquake magnitude? What is the connection between earthquakes and faulting (the earthquake cycle)? How do earthquakes produce tsunamis? How best to mitigate earthquake damage?

4. Earthquake Vocabulary Earthquake: a sudden release of elastic energy stored in the Earth, caused by slip on a fault. The elastic energy propagates as seismic waves. Fault: A surface of discontinuity separating two rock masses, with relative motion tangent to the surface. Focus: Point on the fault where the seismic waves originate. Epicenter: Point on Earth’s surface above the focus. Magnitude: Size of an earthquake, measured by seismic wave amplitude. Seismicity: Earthquake location in space and time. Seismometer: Instrument for measuring seismic wave ground motion.

6. The Earthquake Cycle

7. Increasing Seismic Energy Release

8. Compression waves Shear waves

9. Seismic surface waves These waves do most of the damage to buildings, etc.

10. www.iris.edu

11. Seismicity of the Earth @ 11AM July 13, 2015 www.iris.edu

12. San Andreas Fault Zone: North American-Pacific Plate Boundary Fault Right-lateral strike slip motion

13. Subduction Zone “Mega-Thrust” Earthquakes

14. Tsunami Generation Mechanism

15. Fukushima (Sendai) Tsunami Propagation

16. Fukushima tsunami advancing over agricultural land

17. The earthquake activity in Nepal is caused by the ongoing continent-continent collision between India and Asia. That collision has produced the Himalaya Mountains and the Tibetan Plateau. The motion of India into Asia is essentially perpendicular to the Himalaya Mountains in Nepal. So thrust faulting earthquakes are the most common kind of earthquake in the central Himalayan region. Magnitude 7.8 NEPAL Earthquake April 25, 2015

18. Himalayan Front: A Giant Seismic Gap Waiting to Slip?

19. May 22, 1960 Chilean Earthquake: Largest Seismic Event in History Tsunami 21 m slip Easter Is.

20. Earthquake Response Drills

21. Earthquake Damage Mitigation: Construction Good Bad Fair Awful

22. Tsunami Preparedness Detection Horizontal Evacuation Warning Vertical Evacuation