Question

Name the major tectonic plates. What are the three types of tectonic plate movement?

Answer 1

Hint: There are seven major tectonic plates and several minor tectonic plates. A major tectonic plate is any plate having an area greater than 20 million $km^2$ and a minor is the one having area less than 20 million $km^2$ and greater than 1 million $km^2$ .
There are four types of tectonic plate movement, one of which is a mixed type plate boundary.

Complete Answer:
The tectonic plates are pieces of Earth’s crust and the uppermost mantle which is together referred to as the lithosphere. The major tectonic plates comprises the bulk of the continents and the Pacific Ocean.
The major plates have an area greater than 20 million $km^2$ and there are seven major plates namely –
1. African plate – It is a major plate underlying Africa it straddles the equator as well as the prime meridian. It has an area of 61,300,000 $km^2$.
2. Antarctic plate – It is a major plate containing the continent of Antarctica and extends to the oceans surrounding the continent. It has an area of about 60,900,000$km^2$ making it the fifth largest plate.
3. Eurasian plate – It is a major plate which includes most of the continent of Eurasia and has an area of 67,800,000$km^2$.
4. Indo- Australian plate – This is a major tectonic plate formed by the fusion of the Indian & Australian plate and has an area of 58,900,000 $km^2$ (Australian plate – part of the ancient continent of Gondwana and has an area of 47,000,000 $km^2$ , and the Indian plate – a minor plate separated from the Gondwana with an area of 11,900,000 $km^2$ ).
5. North American plate – It is a large tectonic plate including most of the North – American Greenland and part of Siberia with an area of 75,900,000 $km^2$.
6. South American plate – This plate includes most of the South – American continent and a large part of the South Atlantic and has an area of 43,600,000 $km^2$.
7. Pacific plate – It is an oceanic tectonic plate under the Pacific Ocean with an area of 103,300,000 $km^2$.

Now, there are three types of tectonic plate and one mixed type, they are characterized by the way the plates move. These plates are – divergent plate boundaries (or movement), convergent plate boundaries (or movement), transformational plate boundaries (or movement) and plate boundary zones (the mixed one).
(I) Divergent plate movement – This movement is characterized by the movement of two plates sliding apart from each other. They can be a mid- ocean ridge or a continent – to – continent movement. Examples of such movements are: Mid – Atlantic Ridge and East Pacific Rise and Africa’s East African Rift and Valley and the Red Sea.
(II) Convergent plate movement – This movement is characterized by the movement of two plates towards each other to form either a subcontinent zone or a continental collision. Examples are - the Andes mountain range in South America, and the Cascade Mountains in Western United States.
(IV) Transformational plate movement – This plate movement occurs when two lithospheric plates slide, or perhaps more accurately, grind past each other along transform faults, where plates are neither created nor destroyed. Example for this is - The San Andreas Fault in California.
(V) Plate boundary zones - Occur where the effects of the interactions are unclear, and the boundaries, usually occurring along a broad belt, are not well defined and may show various types of movements in different episodes.

Note: The African plate is also known as the Nubian plate. Minor tectonic plates include – Somali plate, Amurian plate, Arabian plate, Cocos plate, Burma plate, Scotia plate etc.