I know what you are saying, but think about this. The ship itself is much much larger than that small fraction on taris. If you want a reason its there imaging one of those offshoots of orange is debris. Alternative you try seeing a 300 by 300 meter piece of hull in space at approximately 50 miles.
Perspective is a funny thing, you know an Aircraft carrier? A space cruiser is like 20 times larger at least.
Let's put this into perspective, and this is in favor of the above quote.
An Aircraft Carrier..specifically a Nimitz Class Supercarrier is 1092 (333 meters) feet long. A Star Destroyer is 5249.344 (1600 meters) feet long. Figure sizes haven't changed much as far as length (Or I could be wrong.) and rounding down on the Star Destroyer to an even 5249 feet, we're looking at a ship thirty one feet shy of being exactly one mile long, considering a mile is 5280 (1609 meters) feet.
So it's possible some of it actually survived.