Which tectonic Plates do most of the volcanoes and earthquakes border?
Jan 05, 2010
in
Earthquake Questions
I also need to know what the connection is between earthquakes and volcanoes and plate boundaries? Also Why do you think the area around the Pacific Plate is called the Ring of Fire? Its for science so whoever has the best answer I’ll give you ten points. THANK YOU IN ADVANCE.
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2 comments
Mark V on January 5, 2010 at 11:19 pm
The Pacific Plate by itself is associated with most volcanic and seismic activity, which is why it has been colloquially dubbed "the Ring of Fire." There are any number of primary, secondary/minor and microplates interacting with them. Most of the larger earthquakes are associated with transform boundaries, such as the San Andreas Fault system along the Pacific and North American plate boundary. Lesser numbers of earthquakes, but many volcanoes, occur and convergent / subduction boundaries such as the Juan de Fuca plate subducting beneath the North American plate, creating the Cascade Range. Even the Mid-Ocean Ridge, a divergent boundary, has many earthquakes, but they are small – but there are a lot of them. Links below show plates and movement. Some of the links below shows how the earthquakes and volcanoes cluster to define these boundaries.
The simple connect between earthquakes and plate boundaries is that, you have to imagine where rock is moving, up or down, side to side, together or apart, there’s going to be some tension. This tension (stress) is released as seismic activity. Transform boundaries build up the most stress as plates move past each other, so the strongest earthquakes, earthquakes that don’t get released quickly enough to stay small, occur here. These are usually shallow-focus quakes, making them more dangerous.
At convergent boundaries, again, plates are scraping against each other, just along a horizontal, instead of vertical plane. This causes less stress – but still stress – that is eventually released as an earthquake. These are deep-focus earthquakes that are rarely damaging by the time they reach the surface. Further, along these boundaries, where many volcanoes are also created, there is seismic activity directly related to the volcanoes. These volcanoes are formed as the subducting plate melts as it gets deeper into the mantle. This molten rock becomes less dense, so more buoyant that the surrounding rock, so it begins to float to the surface (just that unlike a balloon, it moves much more slowly). When it hits the surface of the crust, it comes out as lava, and begins to create a volcano.
At divergent boundaries (like the MOR), there is an enormous amount of volcanic activity, which only makes sense, since the definition of a divergent boundary is that magma is rising and forcing the plates apart. Obviously, you get a volcano – it just won’t be very spectacular. The only exception of this is on the small nation of Iceland, where the MOR actually reaches the surface. It often has magnificent lava curtains that run for miles.
Check out all of the links below. Even if you just give them a cursory glance, you’ll get good information.
Bflowing on January 5, 2010 at 11:19 pm
The moving of the plates is what causes earthquakes.
There are weakspots in the lower mantle and as the plate moves over them, a volcano can form. This is why you see a lot of volcanoes in a string.
Check out the source below and notice where most of the earthquakes are. This will tell you why it is called the ring of fire.