1. Class Announcements Term Break extra credit option due by end of period today. Sign up to attend a Papago Park extra credit field trip (worth 20 points). Options: Wed., April 16: 10-11AM or 4-5 PM Thurs., April 17: 10-11AM or 2-3 PM

2. Today’s Lecture: Chap. 9 Volcanoes Class presentations: Cancer-causing gas in Beverly Hills CA - Michael Zara Mt. Rainier - Nathan Policar Intermediate volcanoes (cont.) Calderas Volcanic hazards Case Study: Mt. Saint Helens Economic aspects: Hydrothermal activity Mineral deposits Volcanic Activity on Other Planets

3. a. Calderas b. Lava domes u summit crater greater than 1 km wide u from collapse of summit u viscous felsic magma u usually form after explosive eruption of gas-rich magma Some Other Important Volcanic Features

4. Fig. 09.11ab W. W. Norton

6. Volcano starts to erupt. Full magma chamber Main explosive eruption Magma chamber empties. Newly formed caldera Collapsed blocks Empty magma chamber New volcanic cone grows. Lake fills caldera. Ash and debris

8. Fig. 09.29b © 1997 Birke Schreiber

11. Mount St. Helen’s Lava dome

12. Case study: Mt. St. Helens

13. Case study: Mt. St. Helens Located in the Cascade volcanic range, NW US. Result of past/present subduction of oceanic crust in the Cascadia Trench Many volcanoes there are still active

14. 9500’ 8150’ (1350’ shorter!) Case study: Mt. St. Helens l Ejected nearly a cubic kilometer of ash & rock debris l 59 deaths l Ash blown over 11 miles high!

15. Fig. 09.15 W. W. Norton

16. Fig. 09.16abc W. W. Norton

17. Fig. 09.22e Photo by J. Marso, U.S. Geological Survey Volcanic mudflows

18. Mount Saint Helens A lava dome formed in crater after major eruption.

19.  Hydrothermal Systems:  Develop anywhere that fluids coexist with a heat source.  Typical heat source a magma intrusion.  Effects: Alteration of adjacent rocks and deposition of mineral deposits, often of economic importance.  Also a source of geothermal energy. GENERAL FEATURES OF HYDROTHERMAL SYSTEMS

21. 1: Lava flows 2: Ash falls 3: Ash flows 4: Mud flows Videos: Types of Volcanic Eruptions

22. VENUS

23. Volcanoes Elsewhere in Solar System MARS

24. Fig. 09.30a JPL / NASA Olympus Mons: Largest Volcano in the Solar System

25. Olympus Mons, Mars

26. Jupiter’s moon “Io” From Scientific American, Feb 2000

27. l Jupiter’s moon “Io”

28. Fig. 09.30b JPL / NASA Volcanic Eruptions in Progress on Io