For the longest time, prior to stumbling upon this forum, I had a theory that Elantris and the Mistborn series were set on the same planet. The reason being, the mention of people on another continent that the main characters did not know about in Mistborn. I thought that these people were the people in Elantris, and furthermore, that the chasm that suddenly appeared and ruined everything in Elantris was caused by the Lord Ruler moving and reshaping the world. I now know this is wrong, but I still think that the two could be related.
The way I see it, when the Lord Ruler was moving the planet itself around the solar system, this would have had effects on other planets, and if Scadrial and Sel are in the same solar system, then Sel could have been affected. By moving Scadrial past Sel, its gravitational pull could have affected the other planet, causing an earthquake, and therefore the creation of the chasm.
It couldn't be caused by Sazed or Vin from when they held the power, because the Mistborn series takes place after Elantris, but the Lord Ruler would have effected the world one thousand years before, which could put it, chronologically, when the chasm was formed.
We also know that Odium did not cause the chasm, and that it did not occur naturally. This might be easily disproved, however, if Sel and Scadrial aren't in the same solar system, but I haven't found anything to against this being a possibility.
Thoughts?