Question

what could cause the disturbance inside the earth.

Answer 1

Movement of various tectonic plates cause disturbance in earth

Answer 2

The disturbance inside the earth causes an earthquake. This happens when the land develops sudden slips or cracks at a point inside the earth called epicenter. As a result, concentric waves are produced with different movement patterns. Based on the pattern, the waves are classified as primary, secondary and surface waves.