Area doesn't just disappear. I suppose that depending on what's on the land, your area might have a few more potatoes from your northern neighbors and fewer carrots you generously gifted to your southern neighbors.
You could alternatively just deal with your new jagged plot.
Worst case scenario, you're now the owner of the new Turkish Canyon.
I don’t think there’s a universally accepted solution but in California it would be up to the state to figure it out. It would be a great time to be a Real Estate lawyer after a quake there.
Essentially one affected party comes up with a proposed solution, files paperwork with the court, and then all the rest of the affected parties get together (under court supervision) to make whatever changes are necessary until the solution is fair. If the court agrees that it is a fair solution, it becomes final.
You could alternatively just deal with your new jagged plot.
Worst case scenario, you're now the owner of the new Turkish Canyon.