2. Oceanic-Oceanic - __________________________________________________________________________________________________________________ Page 11 Features: Deep Ocean Trenches and island arcs such as of Japan Aleutian Islands (of Alaska)

Deep powerful earthquakes, subduction 2. Oceanic-Oceanic - ____________________________________________________________________________ Page 11 Deep powerful earthquakes, subduction

We are going to fly over Alaska and the Aleutian Islands Page 11 We are going to fly over Alaska and the Aleutian Islands What features should we be looking for? Aleutian Islands

Unimak Island Page 11 Sept 1992. Seen in this southwest-looking, low oblique photograph is Unimak Island, AK, the largest island in the Aleutian chain. The major volcano on the island (snow-capped peak in the center of the photograph), Shishaldin, rises approx. 9400 ft (2860 m) and has been active during the last 175 years, with several eruption occuring recently. The volcano is locally known as “Smoking Moses.” At the southwestern end of the island is the snow-capped Pogromni Volcano. The blue lake situated in a large volcanic caldera, which can be seen midway between Pogromni and Shishaldin volcanoes, is the result of a now extinct volcano that collapsed.

Page 11 Unimak Island and Aleutian Islands, AK, Sept 1992. Three distinctive, snowcapped stratovolcanoes are easily identified in this near-vertical photograph of Unimak Island, one of many volcanic islands in the Aleutian archipelago. The Aleutian archipelago, formed by the collision of the Pacific Plate with the western extension of the North American Plate, forms a northern part of the Ring of Fire that encircles the Pacific Ocean. Unimak Island, the large island nearest the AK peninsula, is separated from the peninsula by Bechevin Bay, shown at the bottom of the photograph. Shishaldin Volcano is the westernmost and tallest of the three featured volcanoes. Isanolski Volcano is the middle volcano (8088 ft or 2465 m.) Unimak Island

Page 11 Put with convergent plate boundary or volcanoes trench

Convergent Boundary _____________________ - - Features: (Ocean-ocean) Page 11 Strong, deep earthquakes Trench, volcanic island arcs

Subduction and Earthquake Depth Page 11 Subduction and Earthquake Depth BLUE= shallow YELLOW= moderate RED= deep

Continental crust colliding with continental crust Page 11 Continental crust colliding with continental crust What features do we expect to find here?

__________________ - - Features: Convergent Boundary Page 11 __________________ - - Features: Convergent Boundary (Continental-continental) Strong, deep quakes Folded Mountains

__________________ - - Features: Convergent Boundary Page 11 __________________ - - Features: Convergent Boundary (Continental-continental) Strong, deep quakes Folded Mountains

Page 11 We’re off to Southeastern Asia, one of the best places to observe this type of plate boundary! China India Nepal

India colliding with Asia forming the Himalaya Mountains 3. Continental- Continental Page 11 India colliding with Asia forming the Himalaya Mountains

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India China Page 11 Himalayas Tibetan Plateau and Himalayas, China, October 1984. The Himalayas and the Tibetan Plateau shown in this photograph were formed and continue to be modified by the convergent collision of two of the world’s great continental tectonic plates, the Eurasian and the Indian-Australian. As a result of this collision that started more than 65 million years ago, the average elevation of the Tibetan Plateau (shades of brown and numerous deep blue lakes) in the intermountain valleys is approx. 16,000 ft (4880 m). The lakes are fed by the snowmelt from the higher mountain ridges and peaks. Words like treeless, cold, barren, windswept, and desolate are good descriptors of the harsh environment that exists on this elevated plateau. Part of the highest mountains in the world, and sometimes called the “rooftop of the world,” the Himalayas create a formidable barrier southwest of the Tibetan Plateau. The snowcapped Himalayas trend in a southeast-northwest arc with more than 30 peaks rising to heights of 24,000 feet (7300 m). Some clouds along the lower foothills of the southwest side of the Himalayas and some snowcapped mountain ridges and peaks are visible in the photograph. Towards the horizon, hazy and dusty conditions seem to exist on the Indo-Gangetic Plain of northern India (southwest) and the Takla Makan Desert of western China (northwest.)

Mount Everest, Nepal 29,035 feet tall! (8850 meters) Page 11

Moderate, shallow quakes Page 11 ________________ - Transform Boundary (Strike-slip fault) Moderate, shallow quakes

c. Transform Plate Boundaries- _____________________________________ Page 11 San Andreas Fault

The most famous and most active transform fault Page 11 The most famous and most active transform fault Other faults are small or unknown in historic time The San Andreas fault is actually made comprises many small faults in addition Earthquakes are repetitive The San Andreas Fault in California

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Divergent Plate Boundaries- __________________________________ 1. Ocean (example)- _________________ Page 11 Where two plates are moving apart Mid Atlantic Ridge

___________________ - - Features: Divergent Plate Boundaries Page 11 Usually minor quakes, shallow depth Mid- ocean ridges, volcanoes, & rift valleys

Earthquake Depth and Plate Tectonic Setting, Selfos, Iceland (June 2000) Page 11

Plate Boundaries Data Table Page 12 Location Type of Boundary Divergent Convergent Transform East Pacific Ridge Aleutian Trench West side of the South American Plate San Andres Fault ✔ ✔ ✔ ✔

Note Packet pages 12-13 questions 1-13 They move the lithospheric plates 35°N, 18°W Divergent Located on a hot spot A C D 25