Plate Boundaries and Crust Types Using the plate tectonics map, find one example
ID: 110532 • Letter: P
Question
Plate Boundaries and Crust Types
Using the plate tectonics map, find one example of each of the following combinations tectonic plate boundary type and crust type. For each one, indicate where it is located geographically, name the plates involved, and list the tectonic, seismic, volcanic, and surface features that found there. Figures 8.16 and 8.17 in the text will help.
Convergent boundary between oceanic crust and continental crust
Convergent boundary between continental crust and continental crust
Divergent boundary between oceanic crust and oceanic crust
Divergent boundary between continental crust and continental crust
Transform boundary between continental crust and continental crust
Explain why Seattle, Washington, and Portland, Oregon, have to worry about the direct effects of volcanoes, but San Francisco, Los Angeles, and San Diego don’t. (Why are there active volcanoes near Oregon and Washington but not most of CA? Think about the different plate boundaries adjacent to these areas)
This table summarizes the characteristics and effects of earthquakes that struck Haiti in 2010 and Japan in 2011. Use this information and your knowledge of plate tectonics, faulting, and earthquakes to answer the questions that follow.
How much larger was the amplitude of the earthquake waves in the Japan earthquake compared to Haiti? (You need to discuss the difference in wave amplitude - how does wave amplitude relate to magnitude?)
Moment Magnitude Focus Tectonic Setting Fatalities Cost Haiti 2010 7.0 8 miles TransformBoundary 222,570 $25 billion Japan 2011 9.0 20 miles Convergent
Boundary 30,000 $325 billion NO AM EURASIAN PLATE PLAT EURASIAN PLATE JUAN DE FUCA AFRICANINDIA PLATE PACIFIC PLATE NAZCA SOUTH PLATE AMERICAN AUSTRALIA PLATE PLATE SCOTA SANDWICH ANTARCTIC PLATE Divergent Boundaries Transform Boundaries Convergent Boundaries Poorly Defined Boundaries
Explanation / Answer
convergent boundary between oceanic crust and continental crust where the two crust converge causing the high density lithospere plate subducting under low density continental crust. Washington-Oregon coastline of United States , the Juan de Fuca plate (oceanic) is subducting under the continental plate of North America. The Cascade Mountain Range are the volcanoes above the melting oceanic plate. Andes Mountain Range situated in the western part of South America is an example of oceanic-continental convergence, the Nazca Plate here is subducting under the South American plate. This type of convergence causes earthquake activity zone that is shallow in depth along the margins of the continents.
In this type of convergence between two continental crusts , the two thick plate collides with each other which are having density lower than the mantle preventing subduction. Due this there occurs compression, causing folding and faulting between the colliding plates.eg. himalayan range is the example of this type of collision where indian plates collides with eurasian plate. The himalayan range is highly seismic as still the collision is taking place between the two plates.
As the divergence occur between the two oceanic crusts, the mantle upwelling is causing lifting of the lithospehere and forming mid oceanic ridge. midatlantic ridge which is between south american and african plate is an example for divergence of two oceanic crusts. Submarine mountains, fissure eruptions, new oceanic floor creation, oceanic basin widening and shallow earthquake activity is observed.
Divergent plate boundary between continental and continental crust, the mantle convection underneath it causes the thick crust above it to arch and thinning later get fractured as rift shape. The plate pull apart causing normal fault on either sides. The central block slide down causing the river and streams flow into the rift valley forminig linear long lake. e.g. East African rift valley located within the red sea is an example for this type and these rift are occupied by number of faults, shallow earthquakes, volcanic activity sometimes, lakes and shallow oceans arms.
Transform plate boundaries are the zone where two plates slide past each other and the fracture zone that is formed by transform plate boundary is called transform fault. These transform faults differ from strike slip as the plate move towards each other whereas the strike slip they move away from each other. e.g.san andreas fault zone locate toward western side of North America. San andreas connects divergent boundary , alpine fault of newzealand are examples of transform plate boundaries.
The San Andreas connecting a diverging plate boundary at the Gulf of California with the Cascadia subduction zone. This cascadia is a convergent plate boundary steretching from vancouver island to california. The oceanic plate which is denser is subducting beneath the less density continental plate offshore of washington, north california , oregon and british columbia. the tectonic processes of Cascadia subduction zone region include deep earthquakes, volcancism, subduction and accretion. The major cities affected are british columbia, seattle, washington, oregon, portland,british columbia and victoria.
Magnitude is a measure of amplitude. If the magnitue increase by 1, it is equal to 32 times increase in the energy released , if this magnitude raised by 2, it means 32 multiply 32 which is more than 1000 times the energy released in the earthquake. The Japan 9.0 earthquake was 1024 times bigger than Haiti 7.0 earthquake.