As a result of the earthquake is a serious level of 8.0 or above on the Richter scale. The earthquake epicenter was under the ocean floor. Or near the coast When the plates move toward each other. Or separated to cause more earthquakes. The intensity of the vibrations of the earth's crust is very little different each time. The area is along the boundaries of tectonic plates, earthquakes often occur frequently. Especially in the area at the edge of a tectonic plate slid beneath the edge of a tectonic plate subduction another plan. It causes severe earthquake And when the area is under sea level. It can cause a tsunami up.