It's not, since you can't actually test any cause/effect with respect to the supernatural.
Attributing cause to the untestable supernatural is the definition of an irrational belief.
While there is considerable discussion among Christians at times about how and when God intervenes in nature, which is itself His design...many of us do understand the implications of God designing nature as being that nature works quite well on its own -- meaning the laws of nature that is, physics.
And so what we see happening in nature is then normally, typically, everyday, simply nature -- physics in action.
But we also know God watches over us, though only in ultimate ways many think (like me). So, where that line is isn't so easy to say, but I do think most things happen just naturally, according to the physics God designated for our Universe.
And then, nature already operating on its own, without interference typically, God will also intervene in both clear ways for those with faith, but also in subtle ways we don't always figure out, also. See? So, you can get more than one viewpoint from believers about whether or not God is intervening in some instance, of course.
But when you think nature operates naturally, by physics, you have a viewpoint that agrees with that of many or even most Christians, and for some even more than they realize, as they simply assume that gravity is working without giving it much thought. It's the background. It's the normal, and not what we usually focus on.
But, as a believer, I think the asteroid that hit Earth 66 million years ago was carefully chosen, or allowed, in order to accomplish what God meant to happen over time (namely to clear a lot of niches so that mammals could ascend to dominate).
Basically, there isn't going to be a simple clear answer from Christians about whether a particular earthquake was modified by God. Some may think so, and others not. But we do know He can alter them, cause or prevent. And many of us think they happen naturally without interference.