The cascadia subduction zone csz megathrust fault is a 1,000 km long dipping fault that stretches from northern vancouver island to cape mendocino california. In the southernmost region, referred to as the gorda deformation zone, the maximum compressive stress a, constrained by earthquake focal mechanisms is ns. The cascadia trench, which marks the subduction zone of all three segments, is less than 100 miles from the coastline. Soviet subs penetrate pacific northwest, newspaper reports. Understanding plate motions this dynamic earth, usgs. What tectonic process is ongoing between baja california and the north american plate mexico. Least destructive among the plate tectonics in british columbia are those classified as divergent.
Learn vocabulary, terms, and more with flashcards, games, and other study tools. This tale would be the catalyst for centuries of dreaming, and exacerbate english and spanish rivalry. There were a few dozen smaller earthquakes spread out around vancouver island and the sunshine coast with a magnitude of 2. Whether factual or fanciful, these ideas shaped later experiences with the region. Plate tectonics have shaped the continents for millions of years. Location of important divergent zones in the pacific northwest. All the cascade composite cones are of the explosive type, their plate tectonics. Subduction at the middle american trench creates volcanoes in central america. The incidence and magnitude of earthquakes in british columbia over a onemonth period in march and april 2015. It is not recommended to use an ipad or a chrome book to do this assignment.
Map of the northeast pacific from johnston and embley 1990. This map shows the three major plate boundaries in or near california. Gakkel ridge is a divergent plate between the eurasian and the north american plate. Facts about the divergent plate boundary explained with a. Plate boundaries convergent divergent transform plate tectonics explains the configuration of topographic features of the earth mountains, valleys, volcanoes, islands, oceanic trenches, faults tectonic plates are composed of the lithosphere move as a coherent mass may contain oceanic crust and continental crust direction of movement. North is to the top, west is to the left, east is to the right. The 2006 tectonic plate boundary map shows all the boundaries by map of tectonic plates and their boundaries. Between the nazca and the antarctic plate lies the chile rise, which is being subducted or pushed. Transform faults do not just connect divergent boundaries. Plate, plate motions, and plate boundary processes. Volcanoes in national parks oregon state university.
Geology of british columbia british columbia unbound. A plate boundary occurs where two plates come together. A divergent plate boundary is a tectonic boundary where two plates. Pioneering along the northwestern edge of the continent mccurdy, james g. Transform push, oblique subduction resistance, and. The blanco, mendocino, murray, and molokai fracture zones are some of the many fracture zones transform faults that scar the ocean floor and offset ridges see. It runs generally northward, with a length of approximately 500 kilometers 300 miles. Yeats is licensed under a creative commons attributionnoncommercial 4.
The midatlantic ridge divides iceland and is the boundary between the north american and eurasian tectonic plates. The molten mantle rock produced by this subduction is responsible for the major volcanoes in the cascade range. Operates in subducted zones, there the subducting oceanic plate, being relatively cool and dense, sinks through the lessdense mantle, pulling the rest of the slab along as it does so slabpull model mantle material circulates in great rolls and also rises from near the coremantle boundary in a manner suggestive of a thundercloud. In the middle of the eastern side is a transform boundary with the north american plate along the san andreas fault, and a boundary with the cocos plate.
What geologist wrote the book the history of ocean basins, which contained the idea of seafloor spreading. What are the three major plate boundaries in or near california figure. Information and resources about the san andreas fault. Transform push, oblique subduction resistance, and intraplate.
Divergent boundarywhere two plates are moving in opposite directions as in a midocean ridge. The rate of plate creation at divergent boundaries varies between. Accepted for publication march 19, 1973 abstract mayers, i. Seattle information provided by the john walker family spy ring has allowed soviet attack submarines tracking u. This is creating an opening for magma to seep onto the sea floor and create new ocean crust. Divergent plate boundaries where two plates move apart, resulting in upwelling of hot material from the mantle to create new seafloor.
The blanco, mendocino, murray, and molokai fracture zones are some of the many fracture zones transform faults that scar the ocean floor and offset ridges see text. The slab dips shallower compared with its counterparts to north and south, which have a dip of 65 harris, et al. The part of california west of the san andreas fault and all of baja california are on the pacific plate. The cascadia trench marks the subduction zone with the north american plate. Examples of oceaniccontinental convergence include. The other two ridges are the gorda and explorer ridges figure 9. Which of the following is not a divergent and divergent. Geophysics program and department of oceanography, university of washington, seattle, wash. You might notice that divergent and transform boundaries often occur. Iceland is an example of a country undergoing a continental divergent boundary. The three types of dynamic plate boundaries are the convergent, divergent. Look at the colored map of magnetic anomalies on the ocean floor, off the coast of the pacific northwest. The east african rift is a divergent plate boundary that is splitting the continent. Convergent boundarywhere two plates collide to form mountains or a subduction zone.
When divergent boundaries occur under continental plates, they form a rift valley. In the middle of the eastern side is a transform boundary with the north american plate along the san andreas fault, and a boundary with the cocos. Cascadia subduction zone pacific northwest seismic network. A transform plate boundary between the pacific and north american plates creates the san andreas fault, the worlds most notorious transform fault. Plate tectonics shape and shake british columbia earthquakes. And with many research institutions dedicated to studying such an accessible fault, the saf has become a household name. The san andreas fault is the most famous fault in the world. The third, the explorer segment, is off the canadian coast. A description of the pacific ring of fire along western north america is a description of the plate boundaries. Pioneering along the northwestern edge of the continent. These two plates are separated by the cascadia subduction zone. Its notoriety comes partly from the disastrous 1906 san francisco earthquake, but rather more importantly because it passes through california, a highlypopulated state that is frequently in the news.
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