Well, yes, perhaps an earthquake could have parted the waters.
Except, so what?
Is the idea that the Israelites were fleeing from the Pharaoh’s armies, and were trapped by the Red Sea, and totally coincidentally there was an earthquake (or high winds, or whatever other natural phenomenon is postulated), and they were able to cross the sea, and when the pursuing army followed they were drowned as the waters rushed back? And God had nothing to do with it? And only later, when they wrote the story down, did the Israelites decide that God parted the waters via a miracle?
The problem with this line of reasoning is that we have no reason to believe anything in the book of Exodus is historical. We have no reason to believe there was a Moses, or that the Israelites were slaves in Egypt, or that they escaped, or that the waters were parted, or anything about the story. There’s no need to invent a naturalistic debunking of the story when there’s no reason to believe the story ever happened.
Just like theorizing that an earthquake coincidentally happened when Gollum fell into Mt Doom with the ring, and that’s what caused Sauron’s death, not the destruction of the ring. Yes, an earthquake could destroy a tower, and dishearten an army. Except The Lord of the Rings never happened. Frodo and Gollum are made up characters. So saying that the real reason for the collapse of the Dark Tower could have been an earthquake is silly.
Now, if you believe the story really happened, because your forefathers vouched for the authenticity of the story, and their forefathers before them, and their forefathers before them, and you believe them, and therefore you believe the story really happened, well, then you believe the part about God doing it too.
If you don’t believe the story happened as described, there’s no reason to invent a naturalistic explanation for the story, since the simplest naturalistic explanation for the story is that the story didn’t happen, period, not that the story happened but the parts about God were added later. If the passages about God were made up after the fact, then the passages about the sea parting were likely made up too.
It’s like looking for a naturalistic explanation of the story of George Washington chopping down the cherry tree. There’s no need to explain the story, because the story was made up.