On this earth there are 7 large plates, namely:
(1) Pacific, (2) North America, (3) South America, (4) African, (5) Eurasian (the plate where Indonesia is located), (6) Australian, and (7) Antartica. Below these plates the convection currents are located and the astenosphere (the inner layer of the plate) becomes heated by radioactive decay like Uranium, Thorium, and Potassium.
This heated part is the source of the lava we often see in the volcano as well as the source of the material that comes out in the ocean bund and forms a new ocean floor. The magma keeps rising upward in the oceanic bunds of the ocean and produces a flow of magma that flows in two different directions and produces a force capable of dividing the oceanic midriver. By the time the ocean floor is split, cracks occur in the middle of the embankment and the melting magma is able to come out and form a new ocean floor.
Then the ocean floor moves away from the middle of the ocean until it finally meets the continental plates and will infiltrate inward because of its density, which generally compounds heavier than the density of the continental shelf. Infiltration of oceanic plates into continental plates is what produce subduction or subduction zones and eventually the lithosphere will re-infiltrate under the astenosphere and reheat again. This incident took place continuously. The earth does move, if it does move, what happens in the tectonic plate meeting area?
Plate meeting area is generally generated a lot of earthquakes and if the source of this earthquake is in the ocean then the possibility of a tsunami. The meeting of the plates is a fault zone and can be divided into 3 groups. They are (1) normal fault, (2) thrust fault, and (3) strike slipe fault. In addition to these three groups there is one more commonly called collision or obduction where both Bnaiks are associated with compressional or firmness or encouragement. The shear fracture has much to do with the style of transformation. Where is Indonesia?
Looking at Indonesia, our region lies in a meeting of the Australian and Eurasian plates where the Australian plate infiltrated into the eurasian zone thus forming a subduction zone along Sumatra, Java, Bali, Lombok, Nusa Tenggara, East and circular in Banda. While Irian Jaya is a meeting place of several plates namely Australian, Eurasian, Pacific, and Philipine. As a result of the confinement of this subduction zone, there are so many volcanoes in Indonesia. That's why people call our area as RING OF FIRE. So do not be surprised if in our country is often hit by earthquake and tsunami because our area is limited by meeting the big plates in the world.