Plate tectonics, volcanoes, and earthquakes

1. Mr. Hajek’s 4th-grade classroom Paradise Canyon Elementary School La Canada, California 3 October 2003 Plate tectonics, volcanoes,and earthquakes Ken Hudnut U. S. Geological Survey

2. Plate tectonics, volcanoesand earthquakes • Part 1 - plate tectonics • Part 2 - volcanoes • Part 3 - earthquakes

3. Part 1. Plate Tectonics Movie by T. Atwater, UCSB

4. Motion between the plates causes earthquakes and volcanoes

5. Earthquakes and volcanoes are driven by plate tectonic motion • As a plate subducted, the Cascades volcanoes and San Andreas fault were born • The subducting plate melts and the magma rises up to form volcanoes • The plates sliding past each other make the active transform faults Movie by T. Atwater, UCSB

7. Worksheet on Plate Edges • Plate edges are of three types • Plates pull away from each other • Plates push towards each other • Plates slide past each other color the plates!

8. Part 2. Volcanoes Eruption of Stromboli, Italy

9. Motion between the plates causes earthquakes and volcanoes This is really bad news for people (like us!) living around the Pacific Rim, also known as the Ring of Fire

10. Why do volcanoes erupt? • Pressure builds up because of heat and trapped gas bubbles • Cracks open and lava, steam and ash blast out • Sticky magma makes tall cone-shaped volcanoes (like Merapi) • Runny magma makes low, broad volcanoes (like Kilauea, Hawai’I)

11. Merapivolcano,Java Strato-volcanoes erupt igneous rocks!

12. Westdahlvolcano,Alaska Volcanoes inflate with magma, and deflate with lava

13. Worksheet on Ring of Fire • Plates crash into each other, causing high mountains and low ocean floor called trenches • Deepest trench is the Marianas (esp. at the ‘Challenger Deep’ location shown on map) • Highest mountain is Mt. Everest color the ring of fire!

14. What about Hawai'i? It's a 'hot spot' Worksheet: hot spot track - islands cool, erode, & sink

15. Part 3. Earthquakes Earthquakes are a global problem Istanbul Tokyo Mexico City Jakarta Santiago

16. Earthquakes are driven by plate tectonic motion • In the past 5 million years, this motion has been steady at about 2 inches per year (that’s 15 feet per century or 30 miles per million years!) • Yes, LA will be in San Francisco • No, LA will not fall into the sea Movie by T. Atwater, UCSB

17. Earthquakes are not only California’s problem $30M of oil each day!

18. Houston, we have a problem… "Big Ones" 1906 1857

19. Southern California is the nation’s most dangerous place for earthquakes - why? Silver linings: State-of-the-art earthquake monitoring arrays Many of the world’s best researchers work within this natural laboratory

20. The San Andreas fault

21. San Andreas fault • Most of the plate boundary motion • 1685, 1812, 1857 eq’s • Big Bend compression • 1971 Sylmar (M 6.7) • 1994 Northridge (M 6.7) • SoCal is now heavily ‘wired’ (much like Japan & Taiwan) • Seismic • GPS

22. GPS

23. ‘A rip in the desert canvas’ - Los Angeles Times Katherine Kendrick, USGS Chris Walls, Earth Consultants International

24. Flying the fault line…

25. Conclusions: • Earth is a very active planet - that’s both a good and bad thing • Humans can survive despite natural hazards - tragic losses from volcanoes & earthquake are not inevitable • Natural beauty results from plate tectonics - we can study & understand the world around us