Your answer would be Tectonic.
Tectonic plates move in various directions, and move slowly. Due to the movement of tectonic plates the earth cracks, and shakes which is called an earch quake. Tectonic plates move constently everyday, and you can't feel it because it's slow. Wehn tectonic plates move quickly, the earth starts to shake. The most common places that have tectonic plates have a higher chance of having an earthquake, even a tusnami.
At the center of the Earth is the core, which has two parts. The solid, inner core of iron has a radius of about 760 miles (about 1,220 km), according to NASA. It is surrounded by a liquid, outer core composed of a nickel-iron alloy. The outer core is about 1,355 miles (2,180 km) thick.
