What should a merchant do with excess damaged goods remaining after an earthquake, which he received four years ago and their owner has not yet claimed them?

The goods you received fall into two categories:

1. Requested and received goods: If these goods are damaged by a natural disaster, such as an earthquake, after possession, then the responsibility lies with the buyer, the sale is not invalidated, and the buyer owes the price.

2. Goods received by mistake: If their owner asks you to keep them for later use and pay their price, this is considered an option for the buyer. What is not damaged from them, is subject to the previous agreement. As for what was damaged by the earthquake, if the damage occurred before use and without negligence from the buyer, then the responsibility falls on the seller, because the goods are within the option period.