GE151j: Introduction to Volcanoes & Volcanology

1. GE151j: Introduction to Volcanoes & Volcanology

2. Bardarbunga eruptive flow, Iceland, 2 September, 2014 http://mashable.com/2014/09/11/iceland-bardabunga-volcano-eruption-photos/

3. We meet: M-T-W-Th @ 9:00-11:30 Robert E. Nelson ("Dr. Bob") Office: Mudd 215 Phone: ext. 5804 e-mail: renelson@colby.edu web page: http://www.colby.edu/geology/ge151/index.html

4. Text Please observe: 1 Regular class: 9:00-9:50 a.m., MWF, = 150 minutes per week THIS class = 9:00-11:30 MTWTh, = 150 minutes per week. Take-home message: Missing ONE DAY of this class is comparable to missing an entire WEEK during the regular semester!

5. Printed syllabus will show topics we're covering, and when, as well as readings. Course grading will be based on: - 1 homework assignment - geography (25 points) -Classroom engagement will be key - 1 hour exam ("midterm") on 15th(100 points) (and yes, spelling and neatness counts!) - 1 joint project on a volcano - 2-person teams (more on this project later)(50 points) - a technical*critique of a Hollywood volcano movie (25 points) *I.e., WHAT IS WRONG with the movie from a technical perspective, based on what you've learned? - final exam (200 points)

6. WARNINGS! * I will deduct ONE POINT on ANY written work for each and every time I see "volcanoe" or "techtonic!" (although volcanoes IS the correct plural form) * There will likely be at least a few days when, due to the lengths of videos, we may run a tad late in class. This WILL particularly be true on days when projects will be presented. * Cell phones are to be turned OFF and put away during class at all times.

7. Course Goals: (1) To come to understand volcanoes, how they work, why they are where they are, what you can expect from them, and why. E.g., Why are the volcanoes of Hawai'i and the Galápagos so different from those of the Pacific Northwest or most other places in the world? Fernandina, Galápagos Mt. Rainier, Washington

8. (2) To gain sufficient background in at least some basic geologic principles, to help you gain an understanding of and appreciation for the physical processes active today in forming the landscape around you. "To a person uninstructed in natural history, his country or seaside stroll is a walk through a gallery filled with wonderful works of art, nine-tenths of which have their faces to the wall." - T. H. Huxley

9. Three common misconceptions to dispel: Myth #1: Volcanoes are the source for the magmas (molten rock).They are the PRODUCT of the eruptions. The magma originates much more deeply in the Earth, in the mantle.And it does NOT originate in the molten outer core - which is mostly iron, with some nickel!

10. The high volcanoes of the Andes, for example, are a product of thousands of volcanic eruptions occurring in the same place, building up a mountain on top of a thick wedge of folded, mashed and mangled continental margin.

11. The view to the south down the length of the Andes, from 15,000 feet (4500 m) elevation. Atacazo is a volcano atop this pile. Photo taken from Pichincha, another volcano. Distance to coast: ~ 100 miles (160 km) (comparable to the distance from here to NH border on I-95)

12. Myth #2. Lava flows are terrifyingly dangerous aspects of a volcanic eruption. They are in fact the LEAST dangerous phase of any eruption, because they're predictable! (That's why people live to tell about them!) Note these actively advancing flows in Hawai'i (left) and on Etna in Italy (right). You don't need to look hard to know these are HOT!

13. Myth #3: Volcanoes are permanent fixtures on the landscape. Like living things, they come into existence, are active for a time (usually measured in thousands to millions of years), and then die - becoming extinct - and gradually erode away. Parícutin, in Mexico, came to life in a cornfield in 1943. Navidad, in Chile, erupted from a flat valley bottom on December 25th, 1988.

14. Eldfell was a new volcano that grew rapidly in Iceland in 1973. Eldfell in 1997.

15. Where ARE the volcanoes? 80% of the active volcanoes in the world lie on the Pacific Ocean rim, the "Pacific Ring of Fire"

16. Other active volcanoes are scattered in Africa, Iceland, the Mediterranean, the eastern Caribbean and Indonesia.

17. Plate tectonics: What makes almost all of it happen.

18. PLATE TECTONICS and CONTINENTAL DRIFT This has REVOLUTIONIZED the Earth Sciences much the way Darwin and Natural Selection did to biology in the 19th century.

19. BASIC PREMISE: The Earth's surface is comprised of 7 major, and about 20 minor, plates that behave as relatively brittle slabs, moving slowly across a more plastic, deformable underlayer, and creating much activity where they are in contact with one another, whether pulling apart, sliding past, or coming towards each other.

20. The relatively brittle slabs, ca. 100 km thick, are called LITHOSPHERE, and comprise the upper part of the Earth's MANTLE as well as all the overlying CRUST. The lithosphere slabs are moved by slow (cm/yr) flow within the relatively plastic AESTHENOSPHERE in the upper mantle.

21. Evidence? A. Not only do continental margins fit together well (as first noticed in the 16th century) ... ... but (B) the geology matches pretty well across those fits, too!

22. C. Fossils of Glossopteris (a plant) and Lystrosaurus (an animal) are found throughout the Southern Hemisphere continents, though modern floras and faunas are completely different. The Glossopteris fossils above, for example, are from Australia (left) and South Africa (right).

23. Again: it is CRITICAL that modern biotas in these areas DIFFER! Examples of the differences in modern biota on different continents. For example, the Great Apes are only found in the Old World, monkeys with prehensile tails and cacti in the New. Eucalyptus is native only to Australia. And hippos are naturally only found in the Old World, mainly in Africa today.

24. D. Glacial evidence: Patterns of glaciation in the Southern Hemisphere around 245-280 million years ago (Carboniferous-Permian) makes NO logical sense unless the continents were in fact connected together.

25. E. Paleomagnetic evidence and dating of the sea floor rocks indicates new crust is being formed at the mid-oceanic rise and ridge system (MORRS), and is moving outwards from this area. Radiometric dating of these rocks shows they get progressively older the farther away one is from the ridge. We have now even observed active volcanism along the crest of this mountain system in several locations.

26. Plate tectonics are driven by CONVECTION in the mantle, produced by heat from radioactive decay. .. and there's increasing evidence that at least in some areas, it's even far more complicated than THIS!

27. If we look at the ocean floor, we see: This mountain range is what is called the Mid-Oceanic Rise and Ridge System (MORRS)

28. If we look closely at the MORRS, we see this topography: Magma upwells to produce volcanism along this ridge.

29. Volcanism is widespread on the Mid-Oceanic Rise and Ridge System (MORRS), which runs throughout the world's ocean system. In Iceland, the rifting is slowly tearing the island in half. Site of the Laki eruption of 1783-85.

30. NOTE that if the Earth's crust is being created anew at the rise and ridge system, one of two things must be happening: Either: A. The Earth is getting progressively larger over time, or B. The crust is being destroyed at about the same rate it is being created.

31. The process of oceanic crust destruction is going on off the western coast of almost ALL of the Americas, from British Columbia to the southern tip of Chile, on all other margins of the Pacific, as well as other places in the world:

32. Imbabura Cotopaxi Tungurahua Imbabura, Cotopaxi and Tungurahua are just three of many volcanoes in Ecuador that have been produced by this process.

33. The same process is going on off the North American coast in Oregon and Washington State: (Andesite, Dacite)

34. Mt. Hood, Mt. Bachelor, and Mt. Shasta of the Cascade Range are also products of the same process. Mt. Rainier Mt. Hood Mt. Shasta Mt. Bachelor

35. Oceanic lithosphere can also be subducted beneath other oceanic lithosphere - creating an island arc system. TYPICAL Island-arc systems include….

36. The Kuril Islands The Aleutian Islands The Japanese archipelago The Marianas Islands The Philippine Islands The Lesser Antilles The Sumatra-Java Arc

37. This is WHY 80% of the active volcanoes in the world lie on the "Pacific Ring of Fire" This volcanic ring is created by subduction of oceanic crust on almostall margins of the Pacific basin.

38. Time for a break ... and a short video ...