According to the theory of plate blank earths plates move very slowly in various directions

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.

i'm sure the answer you are looking for would be

a. an ice age

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