Volcanos and Plate Boundaries?

Question

How is volcanism related to plate boundaries?

Answer 1

There are several processes in Plate Tectonics that cause volcanism, but they result in two main types of volcanism.

Volcanism in subduction is caused by volitals, like H2O, CO2. These are caried down by the plate, mainly in the form of weak minerals. These minerals break down with pressure and temperature into stronger minerals that don't contain water and carbon dioxide. The leftover gases and liquids travel into the mantle (the mantle wedge) and hydrate the mantle, causing melting. The melt rises and then... volcano!

The other main cause is from rising mantle material, which forms decompression melting. Basically, hot mantle is kept from melting by the pressure of the earth at depth. When this material rises, the pressure drops much faster than the temperature, and thus it partially melts. This mainly occurs at divergent boundaries and hot spots, which are areas in plate tectonics that have rising materials or spreading.

Answer 2

Several different ways. Some volcanic activity occurs when the plates diverge, allowing magma to rise up through the "crack." This sort of activity happens on the ocean floor.

The second type occurs when the plate collide and one is pushed under the other. The crust melts and forms magma. The magma then forms a volcano like those seen in the Pacific Ocean.

The final type are hot spots which occur where there are mantel plumes or magma rising up through the Earth's surface. These are like the volcanos that are active over a long period of time like those in Hawaii.

Answer 3

A typical plate boundary of an oceanic plate being subducted beneath a continental plate results in back arc vulcanism. This effect is clearly seen in the Pacific Northwest of the United States, resulting in the Cascades Range and the Columbia River Plateau Basalts. There are other types of vulcanism related to plate boundaries but it is too long to go into all of them.

Answer 4

Plain sense earthquakes are a predecessor to volcanic activity the babylonians were able to tell weather patterns by moon and planetary, comet activity. magnetic feilds are screwed up by comets and therfore effect the earth by causing lava bursts, and earthquakes it tends to happen in cycles if you study historic weather.