please answer this short questions 9. Most volcanoes are located on or near plat
ID: 107325 • Letter: P
Question
please answer this short questions
9. Most volcanoes are located on or near plate boundaries. Give an example of a volcano or a volcanically active area that is not on a plate boundary and give an explanation consistent with the theory of plate tectonics that explains why it exists.
10. Why are there active volcanoes along the west coast, but not along the east coast of the United States?
11. What does it mean to say that the seafloor acts as a "magnetic tape recorder"?
12. What is the approximate rate of seafloor spreading in the Atlantic Ocean?
13. What do the seafloor isochrons show?
Explanation / Answer
9. The most suitable example of a volcanically active area that is not situated on a plate boundary is the Hawaiian Ridge. This is a perfect eample of intra-plate volcanic system as it is situated at the very middle of the pacific ocean.
This is because the area is situated over a active hot-spot resulting from plumes of hot mantle trying to come to the surface by upwelling process. According to the plate tectonic theory the plates are moving in a cnsistent pace towards a fixed direction, but the plume is tend to be fixed in it's position. As the plume moves upward, it bigins to melt to produce magma and evntually produces volcanoes. But, as the plates moves the volcanisms ceases and new volcanoes form at the new position under which the mantle plume is situated thus producing a chain of volcanoes.
The main Hawaii island is now situated over the active hotspot but in the other Hawaiian islands are ceased volcano as the pacific plate moved toward north west and the mantle plume is situated at it's own place.Therefore All the othe volcanic islands are situated northwest of the main Hawaii island.
10. Volcanoes mainly situated along the plate boundaries and also some times at the middle of the plates (associated with hotspot-mantle pplume system). The west coast of United States is situated at the junction of North American plate and Pacific plate thus creating a convergent boundary, wich is a suitable place for volcanic activity to occur.
In addition, the eastern, northern and western boundary of pacific ocean is is associated with large number of volcanic activity, thus it is called the Ring of Fire. The west coast of US lies in this rigion
11. New ocean plates are created at the divergent plate boundaries along the mid ocean ridges. At the both side of the active spreading ridge, long thin stripes of magnetised basaltic ridges are created, each caring the magnetic imprint of the time of it's creation. As the magnetic polarity is changed overtime, we get positive and negetive annomalies of magnetic polarity when we compare it with present magnetic polarity.
Thus the seafloor act as a "magnetic tape recorder" preserving the record of magnetic polarity.
12. The approximate rate of seafloor spreading in the Atlantic Ocean is 2.5 cm per year.
13. The seafloor isochrons show the age of the seafloor as it is drawn by joining the points of equal age.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.