They can’t be an accident, because everything God does is intended.
So, if God created everything perfect, there shouldn't be any disasters: earthquakes, tsunamis etc.
So either he didn't create them perfectly, because he couldn’t therefore, he lacks some qualities: all-powerful, all-wise or because he didn’t want to, therefore being malevolent (he knew that there will be life on Earth, and those disasters could harm this life). Either way it doesn’t look good for him.
Or he created everything perfect but cursed the Earth after the sin of man (like the Earth was guilty of anything…). Even in this case, why would God curse the Earth in order to bring pain to its inhabitants? Isn’t that cruel? Who would do something like that? Even if they sinned why make their life a living hell with random kills? Isn't death enough?
I can't really understand what is in the mind of the beliver when he sees the suffering that a natural disaster brings, because after all they are caused by God, maybe not directly, but indirectly since its his work of art that does them.
So, believers, why do you think God decided (as some point, if you want) that the Earth should have earthquakes?
Don’t give me the “to make us depended on him” answer, because it doesn’t make sense.