earthquakes at convergent plate boundaries
Massive earthquakes are the hallmark of the thrust faulting and folding when two continental plates converge (Figure injured or homeless. Damage from the 2005 Kashmir earth- quake. Click image to the left or use the URL below. URL: Click image to the left or use the URL below. URL:
The Pacific Northwest of the United States is at risk from a potentially massive earthquake that could strike any time. The subduction of three small plates beneath North America produces active volcanoes, the Cascades. As with an active subduction zone, there are also earthquakes. Surprisingly, large earthquakes only hit every 300 to 600 years. The last was in 1700, with an estimated magnitude of around 9. A quake of that magnitude today could produce an incredible amount of destruction and untold fatalities.
Earthquakes in Japan are caused by ocean-ocean convergence. The Philippine Plate and the Pacific Plate subduct beneath oceanic crust on the North American or Eurasian plates. This complex plate tectonics situation creates a chain of volcanoes, the Japanese islands, and as many as 1,500 earthquakes annually. In March 2011 an enormous 9.0 earthquake struck off of Sendai in northeastern Japan. This quake, called the 2011 Tohoku earthquake, was the most powerful ever to strike Japan and one of the top five known in the world. Damage from the earthquake was nearly overshadowed by the tsunami it generated, which wiped out coastal cities and towns This cross section of earthquake epicen- ters with depth outlines the subducting plate with shallow, intermediate, and deep earthquakes. (Figure 1.2). Several months after the earthquake, about 22,000 people were dead or missing, and 190,000 buildings had been damaged or destroyed. Aftershocks, some as large as major earthquakes, have continued to rock the region. Destruction in Ofunato, Japan, from the 2011 Tohoku Earthquake.
convergent plate boundaries
Earthquakes at convergent plate boundaries mark the motions of subducting lithosphere as it plunges through the mantle (Figure 1.1). Eventually the plate heats up enough deform plastically and earthquakes stop. Convergent plate boundaries produce earthquakes all around the Pacific Ocean basin.
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convergent boundaries are where
a) two plates move apart from each other --> b) two plate collide with each other c) two plates slide past each other horizontally d) none of the above
when a lithospheric plate subducts, earthquakes
a) occur at the trench where the plate begins to sink. b) occur along the plate from shallow to intermediate to deep depths. c) stop at the depth where the plate is so hot it deforms plastically. --> d) all of the above
japan is created from convergence of
a) an oceanic and continental plate. b) two continental plates. --> c) two oceanic plates. d) none of these.
the cascades are created
--> a) when an oceanic and continental plate converge b) when two continental plates converge c) when two oceanic plates converge d) when two oceanic plates diverge
damage from the march 2011 tohoku earthquake off japan was overshadowed by damage from the tsunami the quake caused.
--> a) true b) false
in a subduction zone, the most dangerous earthquakes are those at ____ depths.
--> a) shallow b) intermediate c) deep d) any
the pacific northwest is fortunate that it is not very plate tectonically active. it has volcanic eruptions but no real earthquakes.
a) true --> b) false
the damage caused by earthquakes that took place a century or more ago is a good indication of the damage a similar quake would cause today.
e) true f) false
earthquakes at convergent plate boundaries are largest
a) where an oceanic and continental plate converge b) where two continental plates converge c) where two oceanic plates converge --> d) at any of these types of convergent plate boundaries.
transform faults create larger earthquakes than convergent plate boundaries.
a) true --> b) false
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