1. What do you observe about how Earth’s surface changes?

2. Image courtesy USGS How do you think this road came apart?

3. USGS Photo by Bruce Molnia, Terra Photographics What could have made this bridge collapse?

4. USGS Photo by University of Colorado What happened to these railroad tracks?

5. Image by Albert Copley, © Oklahoma University from Earth Science World ImageBank This was a building in Mexico City.

6. USGS Photo by University of Colorado A farm field in California.

7. Photo by Robert A. Eplett/OES CA How could this highway have collapsed?

8. Image courtesy USGS, photo by J. Dewey What a mess!

9. Image courtesy NOAA/NGDC, photo by Pierre St. Amand A sunken ship at a port in Chile, South America

10. What other evidence do you know of that tells us Earth’s surface can change suddenly?

11. USGS Photo by K. Segerstrom Michoacan, Mexico, 1943

12. New Zealand,1974 USGS Photo by University of Colorado

13. How would it feel to be in an airplane near this explosion? USGS Photo by K. Jackson, U.S. Air Force

14. USGS Photo by Lyn Topinka This mountain used to have a peak. It is now a crater.

15. Where did the water go? Image courtesy NOAA/NGDC, photo by Luis Bernucci

16. What could cause such a large wave?