I know why earthquakes exist and what causes them.
From CARM
Sin has affected the world in that there are floods, earthquakes, storms, etc. These are the result of an imperfect world with sin running through it. When Adam fell, the world was affected by his fall. Adam represented all of the created order since he was given dominion over it by God. Therefore, when Adam rebelled, he took the world with him in his fall, and as the Scripture says, it awaits its own deliverance:
"For the creation was subjected to futility, not of its own will, but because of Him who subjected it, in hope 21 that the creation itself also will be set free from its slavery to corruption into the freedom of the glory of the children of God. 22 For we know that the whole creation groans and suffers the pains of childbirth together until now," (
Rom. 8:20-22).