Page 405 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

Greenland
Mid-Atlantic ridge
North American plate
Iceland
Eurasian plate
Transform faults
Chapter 12 The Dynamic Planet 369 in California where the Pacific and North American plates
meet, and along the Alpine fault in New Zealand, the boundary between the Indo-Australian and Pacific plates. The San Andreas, running through several metropolitan areas of California, is perhaps the most famous transform fault in the world and is discussed in Chapter 13.
Focus Study 12.1 describes five principal geomor- phic belts, each distinguished by characteristic bed- rock geology and landforms, that comprise the Western Cordillera in Canada. The development of these belts is explained by interactions at the margins of the Pacific and North American plates over millions of years. The processes involved include convergent and transform motions, subduction, and large-scale faulting.
Earthquake and Volcanic Activity
Plate boundaries are the primary locations of earthquake and volcanic activity, and the correlation of these phe- nomena is an important aspect of plate tectonics. The massive earthquakes that hit Haiti, Chile, New Zealand, and Japan in 2010 and 2011, as well as the 2010 volca- nic eruption in Iceland, focused world attention on these plate boundaries and the principles of plate tectonics. The next chapter discusses earthquakes and volcanic activity in more detail.
The “ring of fire” surrounding the Pacific Basin, named for the frequent incidence of volcanoes along its margin, is evident on the map of earthquake zones, vol- canic sites, hot spots, and plate motion in Figure 12.21.
Inactive fracture zones
▲Figure 12.20 Transform faults. [Office of naval research.]
Animation
Transform Faults, Plate Margins
ridges (Figure 12.20). Some are a few hundred kilometres long; others, such as those along the East Pacific Rise, stretch out 1000 km or more.
Transform boundaries are associated with earth- quake activity, especially where they cut across portions of continental crust, such as along the San Andreas fault
40°
20°
San Andreas Fault
Tropic of Cancer
COCOS PLATE
Mid-Atlantic Ridge
40°
PHILIPPINE PLATE
PACIFIC OCEAN
PACIFIC
0° OCEAN
Equator
INDIAN OCEAN
FIJI0° PLATE
20°
20°
80°
160° 140° 120° 100° 80° 60° 40° 20° 0° 20° 40° 60° 80° 100° 120° 140° 160°
80°
NORTH AMERICAN PLATE
EURASIAN PLATE
CARIBBEAN PLATE
ATLANTIC OCEAN
20°
AFRICAN PLATE
PACIFIC PLATE
PACIFIC PLATE
40°
60°
▲Figure 12.21 locations of earthquake and volcanic activity. Earthquake and volcanic activity in relation to major tectonic plate boundaries and principal hot spots. [Earthquake, volcano, and hot-spot data adapted from U.S. geological Survey.]
NAZCA PLATE
Volcanoes Earthquake zone
SOUTH AMERICAN PLATE
Tropic of Capricorn
Antarctic Circle
ANTARCTIC PLATE ROBINSON PROJECTION
INDO-AUSTRALIAN PLATE
3000 KILOMETRES
Kermadec-Tonga Trench
60°
Subduction zone Collision zone
Spreading ridge offset by transform faults
Motion of plate
Hot spots
(present locations)
0
1500
Liaoning Province